Introduction With the development of society, two-dimensional displays can no longer meet people’s needs. Three-dimensional displays can completely reproduce the scene of world, showing the depth of the object, the sense of hierarchy, and reality because the real world is also three-dimensional. At present, there are a lot of techniques to realize three-dimensional displays, including two-dimensional analog three-dimensional displays, binocular parallax stereoscopic displays, and three-dimensional stereoscopic displays. Nevertheless, two-dimensional simulation three-dimensional display does not produce physical depth of field; Binocular parallax stereoscopic display is limited because of the disadvantages of small angle zoom, causing visual fatigue, and needing to assistant equipment. In contrast, three-dimensional stereoscopic display technology has attracted attention due to its realistic display effect, real-time interaction, and multi-angle observation. Among the related technologies, the static volume display technology based on transparent upconversion luminescent materials shows the most significant advantages.Methods Appropriate composition design is a necessary condition for the nucleation and growth of fluoride nanocrystals in glass. Inthis study, rare earth doped pure red upconversion luminescent oxyfluoride transparent glass ceramics were obtained via the conventional melt-quenching-thermal annealing method. The glass compositions (in mole) are 60SiO2-6Al2O3-7Na2CO3-19NaF- xErF3-yTmF3-(8–x–y)YF3 (x=0–1.6%，y =0–0.4%). The raw materials are SiO2, Al2O3, Na2CO3(Sinopharm Chemical Reagents Co., Ltd.), and high-purity NaF, ErF3, TmF3, YF3(Shanghai Macklin Biochemical Technology Co., Ltd), which were weighed, mixed and ground in an agate mortar. The obtained mixtures were then placed in a sealed alumina crucible and melted at 1 550 ℃ for 45 min under ambient atmosphere. Subsequently, the glass melt was poured into a 200 ℃ preheated copper mould and annealed at 400 ℃ for 5 h to relinquish the internal stress. Finally, the obtained bulk glass was heat-treated at 650 ℃ for 2 h to induce in-situ fluoride crystallization inside the glass to obtain oxyfluoride glass ceramics containing NaYF4 nanocrystals (NaYF4@glass).Results and discussion For Er3+/Tm3+ co-doped NaYF4@glass, the influence of Er3+ doped content was explored and an optimal Er3+concentration of 15% was confirmed. Meanwhile, with the increase of co-doped Tm3+ content, the red emission of Er3+ gradually enhanced due to the energy transfer process between Er3+ and Tm3+. Correspondingly, the color purity of red emission increased to realize the pure red emission upon the 980 nm near-infrared laser excitation. In addition, the temperature dependent spectra (from 80 K to 470 K) of 15%Er–2%Tm: NaYF4@glass were tested. Owing to the electrons at the 2H11/2, 4S3/2 and 4F9/2 levels of Er3+ were populated independently, there was no direct temperatures-dependent electron correlation between the green (2H11/2, 4S3/2) and red (4F9/2) levels of Er3+ ions. With the increase of temperature, the shape of the emission peak remained basically unvaried, indicating excellent chromatic stability. Ultimately, the Er3+/Tm3+ co-doped NaYF4@glass-based three-dimensional prototype display device showed three-dimensional static/dynamic designed red patterns with high color purity and high stability, providing its potential use in new-generation three-dimensional stereoscopic display technology.Conclusions In summary, Er3+/Tm3+ co-doped NaYF4@glass can be successfully prepared via conventional melt-quenching- thermal annealing method. The optimized 15%Er–2%Tm co-doped NaYF4@glass can achieve pure red upconversion luminescence due to the energy transfer process between Er3+ and Tm3+. Owing to that the electrons in the 2H11/2, 4S3/2 and 4F9/2 levels of Er3+ are independently populated, there is not direct temperature-dependent electron correlation between the green energy level (2H11/2, 4S3/2) and the red energy level (4F9/2) of Er3+. Moreover, the Er3+/Tm3+ co-doped NaYF4@glass-based three-dimensional prototype display device is constructured. This study can provide a new idea for the development of pure color transparent upconversion materials for three-dimensional stereoscopic display.

Introduction The energy transfer between lanthanide ions (Ln3+) and transition metal ions (Cr3+) typically leads to luminescence attenuation, which hinders their application in temperature measurement. However, this issue can be effectively addressed by synthesizing polyphase glass-ceramics that separate the Ln3+ and Cr3+ into different nano-crystals.In this study, we designed polyhedral glass-ceramics (40SiO2-20Al2O3-15LiF-10Ga2O3-0.1TmF3-0.1ErF3-0.05Cr2O3-1YbF3-0.5SnO) doped with Ln3+/Cr3+ (Ln3+=Er3+/Tm3+/Yb3+). The up-conversion spectra of Tm3+ and Er3+ in the temperature range of 313–573 K, as well as the temperature-dependent properties of the emission intensity ratio of 2E and 4T2 and fluorescence lifetime decay of Cr3+ were systematically investigated. The results demonstrate that Ln3+/Cr3+-doped polyphase glass-ceramics exhibit excellent performance as a four-mode fluorescence temperature measurement material.Methods Ln3+/Cr3+-doped glass samples were prepared using melt quenching technology, where the raw materials were melted in a lifting furnace at 1 500 ℃ for 1 h. The sample was then poured onto a preheated copper plate to 300 ℃ and shaped by pressing it with another copper plate. Subsequently, the sample was annealed in a Muffle furnace at 450 ℃ for 6 h to obtain precursor glass (PG). Finally, the PG sample underwent heat treatment at 780 ℃ for 2 h to produce glass-ceramics (GC780).X-ray diffraction apparatus was employed to measure the XRD spectra of these samples. FS-5 fluorescence spectrometer was used to measure various spectra including up-conversion and down-conversion spectra at room temperature, power-dependent up-conversion spectra, temperature-dependent up-conversion and down-conversion spectra, as well as temperature-dependent fluorescence lifetime decay curves. Transmission electron microscopy techniques such as selective electron diffraction and high-power transmission electron microscopy were utilized to examine GC780 samples.Results and discussion The diffraction peaks observed in the XRD pattern of GC780 exhibit excellent agreement with the standard cards of γ-Ga2O3 and β-YF3 respectively, indicating the successful synthesis of polyphase glass-ceramics containing γ-Ga2O3 and β-YF3 grains. The excitation and emission spectra of Cr3+ as well as the up-conversion spectra of Er3+ and Tm3+ indicate no energy transfer between Cr3+ and Er3+ or Tm3+. In the variable temperature up-conversion emission spectra of GC780 sample within a temperature range of 313 to 573 K, the emission peak intensity ratio (FIR) I522/I543 and I694/I474，which change with temperature, were selected for temperature detection. As the temperature increases from 313 K to 573 K, there is a decrease in relative sensitive (SR) for I522/I543 with increasing temperature, reaching a maximum value of 1.03%·K–1 at 313 K. On the other hand, SR for I694/I474 initially increases and then decreases with rising temperature, peaking at a maximum value of 1.45%·K–1 at 473 K. In the down-conversion temperature-changing spectra (303–543?K) of Cr3+ excited at 397 nm, the intensity of the luminescence peaks at 615 nm and 720 nm is used to detect the temperature dependence of FIR(I615/I720). When the temperature is from 303 K to 543 K, SR gradually decreases with increasing temperature, and the maximum value of 1.74%·K–1 appears at 303 K. The relative sensitivity is 0.51%·K–1 at 496 K when Cr3+ down-conversion attenuation curve is used to measure temperature dependence.Conclusions Polyphase glass-ceramics doped with β-YF3 and ?-Ga2O3 nano-crystals in Ln3+/Cr3+ (Ln3+=Er3+/Tm3+/Yb3+) have been successfully synthesized by melt quenching method in this work. The up-conversion spectra of GC780 were measured in the temperature range of 313–573 K. The maximum relative sensitivities were 1.03%·K–1 and 1.45%·K–1, respectively, by selecting I522/I543 and I694/I474 intensity ratios. The 2E→4A2 and 4T2→4A2 emission2 peaks of Cr3+ were used for temperature detection, and the maximum relative sensitivity was 1.74%·K–1 at 303 K. In addition, the Cr3+ down-conversion attenuation curve is used to measure the temperature dependence, and the maximum relative sensitivity is 0.51%·K–1 at 496 K. The Ln3+/Cr3+ (Ln3+=Er3+/Tm3+/Yb3+) co-doped β-YF3 and ?-Ga2O3 nano-crystals polyphase glass-ceramic is thus indicated to be a highly promising competitive four-mode self-calibration temperature measurement material.

Introduction Extracted Titanium slag is a type of industrial solid waste produced when titanium is recovered from titanium-containing blast furnace slag using the high-temperature carbonization-low-temperature selective chlorination method.Currently, it can only be disposed of through simple stockpiling and burial, which endangers both the environment and human health.The use of titanium slag to prepare microcrystalline glass with excellent physical and chemical properties is of great significance for the utilization of solid waste resources and the improvement of environmental pollution. Raw material components and heat treatment systems have a significant impact on the microstructure and mechanical properties of glass ceramics. The current work is based on the chemical composition of titanium slag. high-performance glass?ceramics were prepared by melting sintering method by adding quartz tailings to increase SiO2 content. Our study examines how the acidity coefficient (Mk) and sintering temperature affect the crystallization, microstructure, physical and chemical properties of microcrystalline glass. Additionally, we reveal the composition of the physical phase of glass ceramics made from titanium slag and the evolution of crystallization. These findings provide a technical foundation for the synergistic treatment of various solid wastes in the preparation of glass ceramics.Methods Titanium slag and quartz tailings were prepared, combined, ball milled, and sieved accordingly. The required raw materials were weighed exactly, put into a corundum crucible, heated untill the glass liquid melted and clarified. The liquid was then quickly dumped into water, to form glass particles, following a procedure of drying, ball milling, and sieving. The basic glass powder and PVA solution were uniformly mixed before being placed in a press-bar mold and pressed into blank samples, which were then sintered to produce glass ceramics sheet samples.The chemical composition of the raw materials was evaluated using X-ray fluorescence spectrometry. A thermal analyzer was used to perform the DSC analysis simultaneously. An X-ray diffractometer was used to conduct physical phase analysis on raw materials and glass ceramics samples. The microstructure of the glass ceramics samples was observed using a scanning electron microscope (SEM), and their microscopic composition was analyzed using an energy dispersive-X-ray spectrometer (EDS).According to the principle of Archimedes, the bulk density and water absorption of each glass?ceramic sample were measured.The bending strength of glass?ceramics was tested by GB/T4741—1999 three-point bending method. JC/T 2097—2011 industrial microcrystalline plate was used to test the acid etching amount of microcrystalline glass.Results and discussion The morphology investigation reveals that the samples' sintering or fusing steadily improves with an increase in Mk under the same temperature settings. At point of Mk=2.4, the sample begins to soften and distort, whereas at Mk =2.7, it looks to froth.The XRD spectra of the glass ceramics samples demonstrate that the type and amount of the early crystalline phases vary when the Mand sintering temperature increases. Increasing the heat treatment temperature enhances the intensity of the diffraction peaks of the crystalline phases in low Mk glass ceramics samples. At the same sintering temperature, the content of anorthite in glass ceramics samples rises with increasing Mk, while the content of diopside increases in low Mk and decreases in high Mk.The surface and cross-section micro-morphology of the glass ceramics samples demonstrates that the sintering temperature is too low and the materials do not attain the sintered state at lower temperature. With the same Mk, the number of holes in the samples decreases with increasing sintering temperature. As the sintering temperature rises, big closed holes become easier to develop.The features of the glass ceramics samples, together with the results of XRD spectra and SEM analysis, show that Flexural strength and bulk density are mainly related to the type of crystalline phase, crystal content, and appropriately increase the sintering temperature. Mk is conducive to the growth of tremolite and calcium feldspar crystals in the billet, and it also benefits exclusion of porosity, so that the glass ceramics can form a flatter surface, and show higher mechanical-strength, thus to improve the sample's densification, flexural strength, acid resistance, and reduce water absorption as well. At higher acidity coefficients, increasing the SiO2 content in the base glass causes an increase of the liquid phase, which is beneficial for filling pores, reducing the water absorption capacity of glass ceramics, and improving corrosion resistance under acidic conditions.Conclusions With the increase of Mk and sintering temperature, the type and quantity of crystalline phases of glass ceramics samples will undergo high-temperature physical phase reconstruction. Within a certain temperature range, the increase of sintering temperature can promote the growth of crystals in glass ceramics and the intensity of the diffraction peaks of crystalline phases. However, there exists a moderate temperature, above which the transformation of the crystalline phase shows different behavior, that is, low Mk favors the growth of diopside in glass ceramics, while high Mk promotes the formation of anorthite. When the Mk and the sintering temperature are both low, the glass ceramics samples are not completely sintered. This conditions for crystal growth and exclusion of pores are not sufficient. When the Mk and the sintering temperature increase simultaneously, the liquid phase appears in the matrix, which benefits the growth procedure of crystals to form a fixed crystal skeleton. When the sintering temperature is too high or the Mk is too high, the glass matrix begins to melt, and the phenomenon of overcooking occurs, which leads to an increase in the glassy phase and the expansion of pores, resulting in a strong and solid crystal skeleton. The expansion of pores makes the disjointed circular pores in the glass ceramics samples gradually increase. At Mk =1.5 and sintering temperature of 1 190 ℃, the produced material shows a water absorption rate of 0.07%, bulk density of 3.05 g/cm3, acid resistance of 96.6%, flexural strength of 144 MPa, which fully meet the requirements of industrial glass ceramics panels.

Introduction CsPbBr3 perovskite quantum dots have attracted wide attention to be a novel luminescent materials due to their excellent luminescence characteristics. It shows high quantum efficiency (more than 90%) and narrow full width at half-maximum of about 15–20 nm. However, it’s sensitive to water, oxygen, and light, due to its inherent ionic properties and low formation energy.The preparation of CsPbBr3 quantum dot by in-situ crystallization in glass is thus considered to be one of the effective strategies to improve its stability. This work adopts borosilicate as the glass matrix to explore its effect on the glass network structure by changing the molar ratio of CaO/MgO. A further study reveals that there exists regulatory effect on the crystallization behavior and luminescence performance of CsPbBr3. The potential application of the investigated material in the field of optical filters is also explored.Methods A series of CsPbBr3 quantum dot glasses were prepared by the traditional melt quenching-heat treatment method with varying the ratio of CaO/MgO. The obtained glasses were named CAx, where x represents content of CaO. According to the exact ratio, the raw materials are weighed, fully ground in the mortar for 30 min to uniformity. The mixed powder was transferred to a corundum crucible, following with thermal treatment at 1 200 ℃ for 10 min. Subsequently, the melt material was poured into a preheated graphite mold and annealed for 3 h to release the thermal stress until to room temperature. The transparent precursor glass, named PG, was obtained. CsPbBr3 quantum dot glass was obtained by heat treatment of the precursor glass at different temperatures (450?510 ℃) for 10 h. Finally, the prepared CsPbBr3 quantum dot glass was cut, polished, or ground into a powder for further characterization and use.Results and discussion With the increase of the CaO/MgO molar ratio, the average particle size of CsPbBr3 quantum dots gradually decreases from 19.54 nm to 12.59 nm, indicating that the increase of CaO/MgO molar ratio may change the glass network structure to affect the crystallization behaviours of quantum dots. Due to the different radius scale of Ca2+ and Mg2+, they have different energies when occupying the sites in glass matrix. When Mg2+ is replaced by Ca2+, there will be an energy difference, resulting in a decrease in the ability of providing free oxygen, so the BO in the glass increases, which strengthens the glass network. With the increase of the molar ratio of CaO/MgO, the layered structure gradually weakens, and the transition from the layered structure of [BO3] to the framework structure of [BO4] leads to the weakening of the layered characteristics and the dense structure of the glass network, resulting in an increase in the crystallization temperature and a decrease in the average size of the quantum dots. The obtained samples exhibit excellent optical properties. PL spectra of CsPbBr3 quantum dot glass samples with different CaO/MgO molar ratios were heat-treated at 480 ℃ for 10 h shows strongly varied luminescence intensity. The intensity becomes higher until the peak point with the increase of the molar ratio of CaO/MgO. When CaO replaces MgO in small amounts, the glass network expands because the ionic radius of Ca2+ is larger than that of Mg2+, and the influence of molecular weight and atomic radius on the glass matrix plays a dominant role, thereby promoting the migration of Cs+, Pb2+ and Br–, so that CsPbBr3 quantum dots are precipitated in the glass matrix and the luminescence is enhanced. When the molar ratio of CaO/MgO is 2:3 (CA2), the luminescence intensity reaches the maximum value. At this point, the internal quantum efficiency of the CsPbBr3 quantum dot glass sample is 45.2%, the external quantum efficiency is 36.0% under excitation of 455 nm, and the calculated absorption efficiency is 79.6%. After three times of heating-cooling (298?473 K) cycles, the luminous intensity of the optimal sample gradually returns to the initial value, and the peak emission wavelength and FWHM also show obvious temperature dependence and excellent recovery ability, indicating that the CsPbBr3 quantum dot glass has good luminescence thermal stability.Conclusions CsPbBr3 perovskite quantum dots were successfully precipitated in borosilicate glass matrix by traditional melt quenching-heat treatment method. Under the same heat treatment conditions, when the molar ratio of CaO/MgO increases, the average size of quantum dots decreases, and the luminescence quantum efficiency increases first and then decreases. The bond breaking effect of Ca2+ and the mixed alkaline earth effect make the luminescence performance of the CsPbBr3 quantum dot glass sample the best when the molar ratio of CaO/MgO is 2:3, corresponding to an internal quantum efficiency of 45.2%, an external quantum efficiency of 36.0%, and an absorption efficiency of 79.6% under excitation at 455 nm. It also shows good luminescence thermal stability. At the same time, the CsPbBr3 quantum dot glass crystallization is uniform and exhibits high transmittance, which is promising to be applied in the field of optical filters.

Introduction Yttrium aluminum silicate (YAS) glass ceramics, known for their high-temperature resistance, excellent hardness,and mechanical strength, attract wide attention as coating materials for bonding or protecting silicon carbide ceramics. The precipitation of the y-Y2Si2O7 crystalline phase in YAS glass, particularly in comparison with SiC, is advantageous due to the matched coefficients of thermal expansion between y-Y2Si2O7 and SiC. This often leads to its use as a sintering aid or in anti-oxidation coatings for SiC. A glass composition with reported proportions of 22Y2O3-19Al2O3-59SiO2 (in mole) has been designed to selectively precipitate only the y-Y2Si2O7 crystalline phase through process engineering, achieving a softening temperature exceeding 1 400 ℃. However, this glass composition initially undergoes a droplet-type phase separation, resulting in the precipitation of y-Y2Si2O7 crystals in regions enriched with Y2O3 and SiO2. The large gap between these two phase-separated regions leads to non-uniform distribution of y-Y2Si2O7 grain sizes. The cross-sectional morphology exhibits a fibrous structure, which may affect the mechanical properties of the glass ceramics. Compared to fibrous structures, spherical grains have a higher stress distribution, providing the glass ceramics with greater strength. Previous studies have shown that TiO2 and CaF2 are unsuitable as nucleating agents for achieving uniform and fine grains in YAS glass. In this study, a base glass has a composition of 22Y2O3·19Al2O3·59SiO2., The addition of ZnO into the base glass was found to inhibit large-sized phase separation in YAS glass, resulting in a significant refinement of precipitated grain sizes. This led to a substantial improvement in the fracture toughness of the glass ceramics. By observing the crack propagation patterns in the glass ceramics, the toughening mechanism has been elucidated.Methods On the basis of the glass composition 22Y2O3·19Al2O3·59SiO2, a series of glasses with varying compositions,2xZnO·22Y2O3·(19–x)Al2O3·59SiO2 (2x=0, 3, 6, 12, 18, in mole), were obtained by gradually replacing Al2O3 with ZnO at a ZnO:Al2O3 ratio of 2:1. The glasses were subjected to a nucleation temperature (Tg+30 ℃) heat treatment for 3 h, followed by ramping to the crystallization peak temperature (Tc) and holding for 2 h to obtain glass ceramics for testing. Characteristic temperatures of the glasses were determined using DSC at a heating rate of 10 K/min. The glass ceramics, after fine polishing, were etched for 60 s in a 4% HF solution (volume fraction) and then subjected to SEM testing. Vickers hardness of the samples was measured under a 2.94 N load. Fracture toughness (KIc) of the samples was determined under the ASTM C-1421-01b standard Results and discussion As the amount of ZnO gradually increases, the glass transition temperature (Tg) and Tc of the glass decrease progressively. The addition of ZnO reduces both Tg and Tc of the YAS glasses, which is advantageous for lowering the sealing temperature when used in conjunction with SiC ceramics. XRD patterns, SEM images, and EDS patterns confirm that the mechanism for the precipitation of y-Y2Si2O7 in 22Y2O3·19Al2O3·59SiO2 glass belongs to crystallization through phase separation. After the addition of ZnO to YAS glass, nearly spherical grains are precipitated, and the distribution of grains becomes more uniform. With increasing ZnO content, the grain size gradually decreases. The addition of ZnO has a minor impact on the hardness and density of both YAS glass and glass-ceramics. However, a significant improvement is observed in the fracture toughness of the glass ceramics,showing a 65% increase for the glass ceramic containing 18% ZnO compared to the YAS glass ceramic. In glass ceramics formed through phase separation and grain growth, both the size and distribution of grains are uneven. Cracks propagate in a straight-line manner, resulting in longer crack lengths under the same load. In contrast, when cracks propagate in glass ceramics with similar and evenly distributed grain sizes, numerous circumferential cracks around grains occur, leading to increased energy consumption during the crack propagation process and resulting in relatively shorter crack propagation distances.Conclusions As ZnO gradually replaces Al2O3, both the Tg and Tc of YAS glasses decrease. This leads to reduce the sealing temperature when used as sealing materials. With the addition of ZnO, the crystal phases deposited from the YAS glasses transitions from only the y-Y2Si2O7 grains to two phases, i.e., ZnAl2O4 and y-Y2Si2O7. The content of precipitated ZnAl2O4 phase increases with the gradual introduction of ZnO. Although no significant increase in hardness was observed following the compositional change from 0 to 18% of ZnO (in mole), a distinct enhancement of about 1 GPa in hardness after crystallization occurs for the glass with ZnO.Despite a decrease in KIc of YAS glass from 0.82 MPa·m0.5 to 0.71 MPa·m0.5 with the addition of ZnO, the prepared glass ceramics with 18% ZnO (in mole) shows a significant enhancement of KIc, reaching a maximum value of 1.92 MPa·m0.5. The microscopic mechanisms of this enhancement was then revealed by further investigation using SEM.

Introduction X-ray detectors could be divided into direct and indirect types, the latter has cheaper and more stable properties. As the key component of indirect detection, scintillators could convert high-energy photons into low-energy ultraviolet or visible photons. However, the preparation process of traditional scintillation single crystals is relatively complex and costly, and the hygroscopicity of materials also puts strict requirements on their working environment and packaging technology. Moreover, the Tl and Cd are toxic and not environmentally friendly. Therefore, it is very necessary to find new scintillators with simple preparation, low-cost, chemically stable, and environmentally stable properties. The glass-ceramics combines the excellent optical properties of nanocrystals with the high stability and transparency of inorganic glass. High-quality and large-area glass-ceramics could also be easily obtained. Rare earth ions have special energy level structures and luminescence characteristics. Under optical excitation, they can absorb energy and emit light of specific wavelengths, thereby enhancing their scintillation performance and luminescence characteristics, and are resistibility to radiation damage. When the scintillation glass is irradiated by external excitation light sources, the rare earth ions absorb the energy and transfer to high energy level state, and then release energy through radiation transitions. In this paper, rare earth ions are doped into glass-ceramics to introduce efficient luminescent centers. The luminescence performance of ZnGa2O4:Tb3+ glass-ceramics under X-ray irradiation and its indirect imaging ability are studied.Methods To prepare ZnGa2O4 glass-ceramics composing of 52SiO2-10Na2CO3-22ZnO-16Ga2O3-x%Tb4O7 (mole fraction), the raw materials were weighed and ground in an agate mortar for 15 min. After uniformly mixing, the powder was transferred to a 30 ml alumina crucible and melted at 1 600 ℃ for 60 min. The sample was poured onto a preheated copper plate at 350 ℃, pressed into shape, and cooling naturally to form the precursor glass. The precursor glass was treated by heating at 600 ℃ for 4 h to release internal stresses. Subsequently, the samples were heat treated at 700, 750, 800, 850, 900 ℃ for 6 h to form glass-ceramics (GC) with different degrees of crystallinity. Finally, these GC samples were polished or ground into powder for further characterization.The phase of the samples was determined by X-ray diffraction analysis, transmission electron microscopy, and scanning electron microscopy. The photoluminescence properties were analyzed by using the excitation spectrum and photoluminescence spectrum of the Hitachi F-7000 fluorescence spectrophotometer with a 150 W Xe lamp as the excitation source. The transmission spectra were determined by using a TU1810 UV/visible spectrophotometer. A miniaturized X-ray tube with Cu-Kα (λ=0.154 05 nm) radiation source was used for X-ray imaging, maintaining a tube voltage and current of 40 kV and 30 mA, respectively, with a Nikon D500 camera for imaging capture. The radiation luminescence spectra of the samples under X-ray irradiation were measured using a fluorescence spectrophotometer (Ocean Optics, QE Pro).Results and discussion For the precursor glass treated at the temperature ranging from 700 ℃ to 800 ℃, the samples exhibit a transmittance of over 80% in the wavelength range of 400 nm to 800 nm. However, when the heating temperature exceeds 850 ℃, the transmittance of the samples gradually decreases attributing to the increase of the size of ZnGa2O4 nanocrystals precipitated within the glass matrix, resulting in an increase in Rayleigh scattering and the decrease in transparency. Under different doping concentrations of rare earth ion, there is no impurity observed in the XRD diffraction patterns. Additionally, the samples maintain a transmittance of over 80% under different concentrations of Tb3+ doping. Based on the intensity of photoluminescence spectra, the optimal Tb3+ doping concentration is determined to be 1.5%.The ZnGa2O4:1.5%Tb3+ glass-ceramics exhibits a high absorption coefficient in the range of 0 to 50 keV, with a radiation luminescence yield of 13 000 photons/MeV, which is superior to that of commercial BGO in both absorption coefficient and radiation luminescence yield. Additionally, it exhibits a linear response relationship with X-ray dose rates and demonstrates long-term stability under X-ray irradiation. Indirect X-ray imaging by using this material could clearly visualize the internal structure of printed circuit boards with an imaging resolution of 16 lp/mm. Furthermore, the ZnGa2O4:1.5%Tb3+ glass-ceramics could restore its radiation luminescence performance to its initial state via thermal treatment.Conclusions ZnGa2O4:1.5%Tb3+ glass-ceramics exhibits characteristic emissions of Tb3+ under both UV and X-ray irradiation, with a high transmittance of over 80%, which is beneficial for achieving high-resolution X-ray imaging (16 lp/mm). Additionally, under high-energy radiation exposure for a long duration (1 000 h), the RL intensity of ZnGa2O4:1.5%Tb3+ glass-ceramics only decreases by 20%, and the radiation damage caused by high-dose X-ray can be restored through simple low-temperature thermal treatment, which reduce the cost of scintillators and meet the long-term lifetime. This study demonstrates that ZnGa2O4:1.5%Tb3+ could provide high-quality, efficient, and precise imaging results, and making it promising for applications in medical imaging and non-destructive testing.

Introduction With the continuous development of laser technology, ultra-narrow linewidth lasers show important application prospects in many fields. However, the output linewidth of conventional semiconductor laser chips is usually large, which cannot meet the practical application requirements. Therefore, it is of great significance to study the key technologies for preparing ultra-narrow linewidth lasers. As a new type of optical component, volume Bragg grating, with the advantages of tunable diffraction wavelength, stable laser wavelength, and narrow linewidth, has become an effective way to solve this problem. This work tried to prepare 1.5 μm volume Bragg grating (VBG) based on chlorine-containing PTR glass to meet the demand for ultra-narrow linewidth lasers in the fields of new generation of coherent laser communication, LIDAR, and high-precision fiber sensing. Methods The glass samples were prepared as long strips with a diameter of 5 mm and a length of 28 mm. The thermal expansion was recorded by warming the glass samples from room temperature to 800 ℃ at a rate of 10 ℃/min using a DIL 402PC/4 high-temperature thermal expansion meter from NETZSCH, Germany. The samples of chlorine-containing PTR glass before and after exposure were also tested by differential thermal analysis using a Q600SDT integrated thermal analyser from TA Instruments,USA. This is an important parameter to understand the dimensional stability of the glass during temperature change. A D2 PHASER type X-ray diffractometer from Bruker, Germany was used to analyze the changes in crystal structure of chlorine containing PTR glass before and after exposure, nucleation and precipitation heat treatment to understand the structural evolution and property changes of the material.A Lambda 750S UV?Vis?NIR spectrophotometer from Perkin Elmer, USA was used to study the optical absorption properties of chlorine-containing PTR glass before and after exposure, nucleation and decrystallisation heat treatments, and to understand its absorption capacity at different wavelengths.The glass powder was mixed with high purity KBr and pressed into tablets, and then scanned by infrared spectroscopy with a scanning speed of 0.158 cm/s. A Nicolet iS50 Fourier infrared spectrometer from Thermo Fisher Scientific, USA was used. The samples were then analyzed for their infrared transmittance properties. The infrared transmission properties of the samples were analyzed to understand the transmission properties of the materials in the infrared band. An in Via-Peflex type Raman spectrometer from Renishaw, UK was used. The molecular vibration and vibrational information of the samples were further analyzed through Raman spectroscopy to further understand the structure and properties of the materials.Results and discussion Firstly, the thermal properties of the new PTR glass were investigated. Its transition temperature (Tg) and softening temperature (Tf) were 446.2 ℃ and 499.4 ℃, respectively. These two parameters are important for glass processing and applications. The coefficient of thermal expansion was similar to that of bromine-containing PTR glass in the temperature range of 30-400 ℃, indicating that the substitution of Br? by Cl? has a small effect on the thermal expansion properties of PTR glass.Secondly, it was found that NaF nanocrystals were successfully precipitated from chlorine-containing PTR glass after the precipitation heat treatment by XRD (X-ray diffraction) and TEM (transmission electron microscopy) inspection. These nanocrystals were distributed as dark grey elliptical particles with a particle size of 5 nm in the glass. high-resolution transmission electron microscopy (HRTEM) further revealed the lattice structure of these nanocrystals, and the spacing of adjacent crystal planes corresponded to the (111) crystal planes of NaF crystals. In addition, the detection of absorption spectra of chlorine-containing PTR glasses showed a new broad and weak absorption peak at 413 nm, which was attributed to the absorption of plasma AgCl.Compared with the plasma AgBr absorption peak precipitated in the conventional PTR glass, the plasma AgCl absorption peak of the chlorine-containing PTR glass blueshifted in the UV sepctrum, which supplied the possibility of developing short-wavelength VBG products. In terms of glass structure, Raman and Fourier infrared spectroscopy analyses showed that the structure of chlorine-containing PTR glasses did not change significantly after the precipitation heat treatment. Finally, the article explores the performance of chlorine-containing PTR glasses for VBG applications. The diffraction efficiency of VBG was found to be positively correlated with the refractive index modulation and grating thickness. Under the same conditions of exposure dose and heat treatment process, increasing the thickness of VBG can significantly improve its diffraction efficiency. The experimental results show that the centre wavelengths of VBGs with thicknesses of 10 mm and 16 mm are 1 549.44 nm and 1 549.48 nm, respectively, and the half-height full widths are 0.0611 nm and 0.0570 nm, respectively.Conclusions Novel chlorine-containing PTR glass components were designed and prepared using a two-step melting process to produce photothermally sensitive refractive glasses with a homogeneity of 10?6. 325 nm UV irradiation led to a decrease in the transition temperature and the onset of precipitation of the PTR glass, and an increase in the precipitation properties, which is very favourable for the preparation of high-quality VBGs. XRD and TEM results confirmed that NaF nanocrystals of an average size of 5?nm were precipitated from the chlorine-containing PTR glass. NaF nanocrystals with an average particle size of 5 nm. Raman and FTIR spectra showed that holographic exposure and heat treatment further enhanced the glass network structure. A reflective volume Bragg grating with a centre wavelength of 1.5 μm was prepared, with a diffraction efficiency of 50% and a half-height full width of 0.0570 nm, which sets the foundation for the development of 1.5 μm ultra-narrow linewidth semiconductor lasers.

Because of properties such as wide band transparency, good chemical and thermal stability, low dispersion, high laser damage enhance the optical and electrical properties of glass. Metals, oxides, non-oxides, and semiconductors can be dispersed in glass-ceramics, and these nanocrystals precipitated in glass can not only enhance the mechanical properties of the glass, but also provide properties that the glass substrate does not have.When these nanocrystals are introduced into glass, the bright color of the glass will appear due to the localized surface plasmon resonance (LSPR) effect. This optical effect based on the particle size can be interpreted as: the free electrons of metals limited to subwavelength nanoparticles will have LSPR under certain frequency excitation. This effect will cause the electric field near the surface of the nanoparticles to increase by 3 to 6 orders of magnitude, thus greatly promoting the interaction between light and matter, and it shows the strong linear absorption in the resonance band. Its absorption cross-section is at least 2 orders of magnitude larger than that of quantum dots, organic dyes and various optically active ions.Among the different compositions of nanocrystals, precious metal nanocrystals may be one of the earliest used by humankind. In most oxide glass systems (such as silicate glass systems), noble metals such as Au, Ag, and Pt are difficult to form stable chemical bonds with the glass network. After heat treatment, these metal elements are easy to precipitate in clusters or nanocrystals. At present, a variety of noble metal nanocrystalline doped glass systems have been widely studied. In addition, some other plasmon materials such as non-precious metals can also be precipitated from some specific compositions of glass. Except for noble metal, nanocrystals that can be precipitated from glass include oxide and non-oxide systems such as ZnO:Sb, Cu2–xSe, RuO2, etc. At present, the most widely used methods to precipitate plasmon nanocrystals from glass are heat treatment, ion implantation and femtosecond laser induced precipitation. Heat treatment is a common method for precipitating nanocrystals into the glass. The advantage of the heat treatment method is that it’s easy to operate. The disadvantage is that even after the same heat treatment process, the precipitation state of the nanocrystals cannot be guaranteed to be completely consistent, and it is difficult to fine-tune the size, distribution and shape of the nanocrystals. The ion implantation method is to accelerate the target doped ions into a high speed ion beam by a strong electric field and drive it into the glass matrix. Then the injected ion is crystallized by heat treatment. The advantage of ion implantation is that any kind of ion can be injected into the glass theoretically. The shape, size and structure of the nanoparticles can be controlled by adjusting the implantation parameters. The disadvantage of ion implantation is that the equipment is expensive and nanocrystals can only be precipitated on the glass surface, and the size and depth distribution of nanocrystals is not well controlled. The femtosecond laser irradiation method uses femtosecond laser with short action time and high spatial freedom to control the size and spatial distribution of nanocrystals in glass. The nanoparticles can dissolve again through femtosecond laser.It is generally believed that glass does not have the second-order nonlinear polarization effect and the third-order nonlinear response of glass is relatively weak since it’s isotropic. We can involve nanocrystals with LSPR effect into glass to enhance its nonlinear polarization performance. Due to its strong resonance absorption in the LSPR band and the nonlinear response here also appears the extreme value, the plasmon nanoparticles participated glass has a wide application prospect not only in the frontier fields such as optical grating, optical storage, sensing and detection, but also in the nonlinear fields such as ultrafast optical switching,optical modulation and pulse laser.Summary and prospects The optical properties and preparation methods of various kinds of plasmon nanocrystalline glasses containing precious metals and non-precious metals are briefly introduced in this paper. Due to the LSPR effect of plasmon materials, glass containing plasmon nanocrystals exhibit huge resonance absorption and strong nonlinear response in the resonance band, which makes them widely used in ultrafast photonics and nonlinear optics fields. However, the strong resonance absorption of plasmon also means huge linear absorption loss, which limits its application in, for example, the nonlinear optical switching. In addition, in the glass matrix, the growth of plasmon nanocrystals is limited. It’s very difficult to control their geometric structure and composition,which makes their optical properties difficult to control. The emergence of ultrafast laser processing technology provides a new means for the spatially selective precipitation of plasmon nanocrystals, which also serves as a powerful processing tool for developing photonic devices based on this kind of glass.

The infrared wavelength of 1?5 μm contains important communication and atmospheric transmission window, which has great application value. At present, the luminescent materials used in this band mainly include rare-earth ion-doped crystal and glass.Because of the large absorption and emission cross section and low phonon energy, crystal material is widely used in the field of solid state lasers. However, the long preparation cycle and limited sample size restrict its further development. Glass material possesses excellent machinability and good fluorescence characteristics, being widely used in communication, laser and other fields. Oxide glass is mainly used in near-infrared (NIR) range being limited by its large phonon energy. Rare-earth ion-doped fluoride glass can be used in visible and mid-infrared (MIR) range, but limited by its poor chemical and mechanical properties. Rare-earth ion-doped glass ceramics shows excellent optical properties from crystal materials, and good physical and chemical properties from glass materials,making it a promising infrared luminescent material.One of the most important properties of glass ceramic is the transmittance, as the crystalline phase in glass would cause light scattering inevitably. Based on the scattering theory, one could find that the influence factors of transmittance of glass ceramics include the size and distribution of the crystalline phase and the refractive index difference between the crystalline phase and the glass phase. To realize transparent glass ceramics, the size of the crystalline should be less than 30 nm, and the refractive index difference should be less than 0.3.The status and characteristics of rare-earth ion-doped infrared glass ceramics, including oxyfluoride silicate, tellurate and germanate glass ceramics, were summarized and analyzed. The application and research progress were overviewed. Oxyfluoride silicate glass ceramics is the most widely investigated material. Phase separation would generally happen, leading to the formation of fluorine-rich nanophase before the crystallization process, and would affect the crystalline phase properties, such as crystalline size.The improvement of fluorescence characteristic is summarized, including the aspects of fluorescence intensity, lifetime and bandwidth. Anti-glass phase can be precipitated in tellurate glass ceramics, which is difficult to realize in other glass or preparation alone, giving the material system unique properties. The influence of crystalline phase in tellurate glass ceramics is carefully discussed. Infrared germanate glass ceramics is reported in few glass composition systems, and their properties are introduced. With the greatly improved fluorescence properties, glass ceramic could be used in the fields of infrared fiber laser, infrared whispering gallery modes (WGM) resonator microcavity laser, temperature sensing and luminous anti-counterfeiting and so on, the application cases reported so far are summarized and introduced.Summary and prospects Glass-ceramics shows excellent optical properties from crystals, and good physical and chemical properties from glass materials, facilitating its important application in infrared wavelength range. Based on the scattering theory, the factors affecting the transmittance of glass ceramics are introduced, and the conditions for realizing transparent glass ceramics are summarized. The most widely reported glass ceramics systems, including oxyfluoride silicate, tellurate and germanate glass ceramics, are introduced. The crystallization mechanism is analyzed, but remains unclear, for example, how to understand the precipitation of anti-glass phase in tellurate glass ceramics. A variety of low phonon energy fluoride or oxide crystalline phases can be precipitated in germanate glass ceramics. However, the infrared germanate glass ceramics is limited to a few systems, and there is plenty of room for exploration of infrared germanate glass ceramics luminous materials. Finally, the application of infrared glass ceramics is introduced, especially in the field of laser. Under the condition of balancing the scattering loss caused by the crystalline phases, glass ceramics shows better laser performance than the precursor glass, which indicates that glass ceramics luminous materials have great application prospects in the field of infrared laser. However, there is few reports on other applications of rare-earth ion-doped glass ceramics in the infrared range at present. It’s expected that the development of relative applications based on unique properties of glass ceramics will promote rare-earth ion-doped glass ceramics to become the next generation infrared luminous materials.

Introduction MOF gas separation membranes have attracted much attention due to the large BET surface area, flexible functional groups, adjustable structure, and good thermo-chemical stability, which can significantly improve the separation efficiency and purity of the gas separation process. However, MOF gas separation membranes have unavoidable grain boundaries and are prone to non-selective defects, which greatly destroys the intrinsic separation properties of pure MOF materials, posing a serious of challenges during the preparation and application. MOF glass membranes is an emerging type of gas separation membrane with the advantages of easy processing, no grain boundary defects and permanent porosity, and have become a new access for the preparation of high-performance gas separation membranes. However, the typical MOF glass membranes are normally formed on support layers, and the presence of the supporting layers greatly limits the processability and gas permeability enhancement. In this work, a novel preparation method of self-supported MOF glass membranes is proposed, and a serious of self-supported ZIF-62 glass membranes performing excellent CO2/CH4 gas separation property are obtained.Methods In the present work, ZIF-62 crystals were prepared according to the previous literature. Zinc hydroxide, zinc acetate dihydrate (purity 99%, manufacturers are Shanghai Aladdin Biochemistry Science and Technology Co., Ltd.), imidazole (purity 99.5%, manufacturers are Anhui Zesheng Science and Technology Co., Ltd.), benzimidazole (purity 96% manufacturers are Shanghai McLean Biochemistry Science and Technology Co., Ltd.), N,N- N,N- dimethylformamide (purity of analytical purity, the manufacturers are Sinopharm Chemical Reagent Co., Ltd.), etc were used. Then, the ZIF-62 crystals were pressed to thin pellets in specific molds, and were heat-treated by a preset heating procedure, so as to prepare the homogeneous and dense self-supported amorphous ZIF-62 glass (agZIF-62) membranes. The difference of the properties between ZIF-62 crystals and agZIF-62 membranes were characterized. After that, self-supported agZIF-62 membranes with different thicknesses were prepared by changing the dosage of ZIF-62 crystals. The influence of thickness on the surface morphology and the CO2/CH4 separation performance of self-supported agZIF-62 membranes were investigated.Results and discussion It is proved by XRD, DSC and TG curves that the ZIF-62 crystals will be fully melted and transformed from crystalline to amorphous glassy state under the heat treatment condition of holding at 440 ℃ for 20 min. Meanwhile, the chemical bonds and ligands of the periodic crystalline structure of the ZIF-62 crystals will not be changed after heat treatment verified by FTIR and 1H NMR analyses.According to the SEM images, it can be observed that the surface of self-supported agZIF-62 membranes is dense without obvious defects, indicating that the prepared self-supported agZIF-62 membrane qualifies the process requirements of gas separation.Combining with XPS and adsorption isotherms of CO2 and CH4, it is proved that the self-supported agZIF-62 membranes have an excellent CO2/CH4 separation performance. With increasing thickness of self-supported agZIF-62 membranes, the CO2 permeance gradually decreases, while the separation selectivity of CO2/CH4 is improved. What’s more, the self-supported agZIF-62 membrane possesses good performance and long-term stability in CO2/CH4 separation.Conclusions ZIF-62 crystals with uniform particle size were prepared by liquid-assisted ball milling method, and self-supported ZIF-62 glass membranes were prepared by pressing ZIF-62 crystal powders in special designed molds succeeding with heat treatment.The thickness of the agZIF-62 membranes can be easily regulated to obtain gas separation membranes with excellent gas separation performance. The prepared agZIF-62 membranes also show excellent long-term stability with their performance remaining essentially unchanged during continuous testing for about 48 h, which is potentially advantageous for industrial CO2 separation. The proposed scheme for the preparation of self-supported ZIF-62 glass membranes is highly adjustable. By changing the shape of the mold,self-supported MOF glass membranes with different shape and size can be obtained, giving advantages of the processability of MOF glass membranes, which is of great significance for the application of MOF glass membranes in different fields.

Introduction Metal-organic frameworks (MOFs) exhibit excellent tunability in structure, primarily due to the mutual substitution and doping of central ions and organic ligands. Changes in central ions and organic ligands could impact their glass-forming stability, pore size, catalytic ability, and other physicochemical properties. For example, the MIL-100 metal-organic framework materials, centered around chromium ions, exhibits high stability and catalytic activity in oxidation reactions. However, replacing chromium ions with aluminum ions will lead to decreased stability and catalytic activity in oxidation reactions. Therefore, exploring the mutual combinations of different metal ions and organic ligands is crucial for developing new MOFs. Fe-MOF, characterized by highly controllable pore structure, excellent catalytic performance, and magnetism, is widely applied in the fields of gas adsorption and separation, catalysis, drug delivery, and environmental protection. However, the activity of Fe ions induces a low thermal stability,which consequently leads to the decomposition of most Fe-MOF crystals prior to melting. This impedes the glass transition process through melt-quenching. In this study, a solvent-free method was utilized to prepare a Fe-MOF crystal, which was subsequently transformed into glass state via melt-quenching. The morphological and structural evolution of this Fe-MOF during heating, as well as the mechanism underlying its glass transition, were thoroughly investigated.Methods In a meticulously controlled environment within a glove box featuring extremely low levels of oxygen and water content(oxygen content ≤0.282 mg·m–3, water content ≤0.3 mg·L–1), the mass of 1.86 g ferrocene and 1.362 g imidazole were weighed,blended together within a polytetrafluoroethylene container and sealed within a sturdy steel outer casing. Subsequently, the reaction vessel was transferred to a high-temperature blast drying oven, following by a controlled reaction process at 150 ℃ for 96 h. After the reaction, the product was washed with dimethylformamide (DMF) until the washing out solution turned transparent. Ultimately the sample was dried within a vacuum drying oven operating at a pressure of –0.1 MPa and a temperature of 80 ℃ for 12 h,permitting the acquisition of the FCIR crystals. To further manipulate the FCIR material into a glassy state, a melt-quenching technique was employed. Approximately 15 mg FCIR crystal were transferred into a specialized platinum crucible, which was then positioned within the Differential Scanning Calorimeter (DSC). The sample undergoes a controlled heating process at 10 ℃·min–1until 500 ℃ under an argon atmosphere flowing at 40 mL·min–1. Subsequently, the sample cooled to room temperature at 20 ℃·min–1.The thermodynamic behavior characterizations of all the samples were conducted using a Netzsch STA449 F1 instrument.Room temperature powder XRD data (2θ=5° to 50°) were collected with a Bruker D8 Advance diffractometer using Cu Kα(λ=1.540 6 ?) radiation. The surface appearance were acquired by Olympus CX33 optical microscope and Zeiss sigma 500 field emission scanning electron microscope (3 kV). The structural changes were characterized through FT-IR and FT-Raman, which obtained by Bruker INVENIO-S Fourier infrared transform spectrometer with a spectral resolution of 4 cm?1 and Thermo Fisher DXR 2xi spectrometer with a laser of 1 064 nm, respectively.Results and discussion FCIR go through three processes during the formation of glass: (ⅰ) the terminal imidazole molecules connected to Fe(II) release at 210–301 ℃ with a weight loss of 19.4%, corresponding to the first peak of DSC curve; (ⅱ) the crystal melting at 398–426 ℃ according to the second peak of DSC curve; (ⅲ) the liquid continues to be heated to 500 ℃ and then cooled to room temperature to form glass, which is certified by the absence of the Bragg in the XRD patterns and Tg appeared in the DSC curve. Remarkably, the loss of mass rapidly occurres at 535–575 ℃, which is relative to the thermal decomposition. In addition, the optical and SEM images of FCIR show morphological changes. The release of imidazole disrupts the surface structure of the crystal,leading to the formation of numerous micropores and irregular cracks. The molten sample exhibits a round periphery and the surface shows deformations and wrinkles, indicating that the molten state of FCIR possesses a very high viscosity. By combining FT-IR and FT-Raman spectroscopy, it can be demonstrated that during the process of heating at 210–301 ℃, the terminal imidazole in the Fe-IM6 octahedra disappeared. These findings provide insights into the structural evolution and thermal properties of FCIR at different temperatures, offering important clues for further research on the properties and applications of this material.Conclusions A Fe-MOF crystal (FCIR) was obtained using a solvent-free method and vitrified through melt-quenching. The release of terminal imidazole led to the transformation of the Fe-IM6 octahedral into Fe-IM4 tetrahedra, which were convinced by FT-IR and FT-Raman spectra. Subsequently, the crystal underwent melting, resulting in a disordered structure at high temperatures, which was retained through rapid cooling to room temperature.

Introduction MOF-based electrolytes exhibit excellent chemical and thermal stability, which can improve the service life and safety of the whole battery. The research of MOF electrolytes is expected to promote the progress and development of solid-state battery technology with high energy density and high safety.The MOF electrolytes has more grain boundaries, which tend to cause interfacial problems such as dendrite growth. In order to eliminate the grain boundaries of MOF, vitrification is a more effective strategy. However, the strong coordination bonds between the metal and organic ligands in MOF lead to high melting points and higher energy consumption required for the MOF glass preparation. In addition, the melting point and decomposition temperature of MOF are very close, and only several MOF can melt when heated, and most of MOF will decompose before melting, accompanied by carbonization of organic ligands, and oxidation of metal ions. Therefore, for most MOF crystals, it is challenging to transform them into glass state by the conventional melt-quenching method. To expand the variety of MOF glasses, researchers have increased the entropy of melting by introducing functional groups with electron-absorbing ability and modified MOFs by strategies such as ion exchange and surface engineering, thereby lowering the melting temperature of MOFs. However, there is no clear mechanistic guidance for the melting point regulation of MOF crystals, and the relationship between its coordination bonds and its melting process is still unclear.Methods By introducing different functional groups with different electron-withdrawing/donating effects on organic ligands, the strength of coordination bonds between metal ions and organic ligands can be adjusted, through which the mechanism and influence law of MOF melting point regulation is investigated. The ligand and metal ions were dissolved in 15 mL of DMF, and then the above solutions were heated and held at 130 ℃ for 48 h. After cooling, the products were collected by centrifugation, washed out with DMF (dimethylformamide) for three times, and finally dried under vacuum at 120 ℃ for 12 h. The obtained TIF-4 crystals were placed into a tube furnace and further held at 380 ℃ for 5 min under argon gas atmosphere, then cooled to room temperature to obtain TIF-4 glass (agTIF-4). A series of TIF-4 crystals using different halogen groups with same structure were prepared via solvothermal method at 130 ℃ in DMF. The strength of the coordination bonds was investigated via FTIR and DSC, from which the influence of the coordination bonds on the melting behavior of MOF were investigated systematically.Results and discussion With the enhancement of the electronegativity of functional groups or the increase of the content of strong electronegative functional groups, i.e. the enhancement of the electron-withdrawing effect of functional groups, it can weaken the coordination bond between the ligand and the metal centre and lower the melting point of the MOF; on the contrary, through the introduction of electron-donating groups (methyl groups), it can enhance the coordination bond through the electron-donating effect and increase the melting point of the MOF. A series of TIF-4 crystals using different halogen groups and same structure were prepared,and the Tm of TIF-4 (from 375 ℃ to 295 ℃) gradually decreased with the enhancement of the electron-withdrawing ability of the halogen functional groups. The strength of the coordination bond was regulated by the electron-withdrawing/donating and the low-temperature preparation of MOF glass was realized. Meanwhile, it provides more theoretical guidance for the preparation of MOF glass, effectively avoids the decomposition of MOF in the melting process, improves the quality of MOF glass, reduces the preparation cost of MOF glass, and provides the theoretical basis and technical support for the application of MOF glass in the field of electrolytes and other fields, and also has a certain role in promoting the development and application of MOF.Conclusions The relationship between the electron-withdrawing/donating of functional groups on organic ligands and the strength of coordination bonds is clarified, and its influence on the melting point of MOF is revealed, which facilitate the preparation of MOF glass with low melting temperature and high thermal stability. This work shows that the electron-withdrawing/donating effect could be utilized to regulate the melting point of MOF, which provides an effective strategy for the preparation of more different types of MOF glasses. This work could promote the large-scale preparation of low-cost and high-quality MOF glasses and promote the practical application of MOF glasses in different fields.

Metal-organic frameworks are a class of organic-inorganic hybrid and crystalline materials based on coordinatively bonded porous network. But the structure and function have been seldom investigated. The effective processing of MOF devices have always been hindered by the intrinsic feature of crystalline powders. The utilization of thermal rheology of glass material is expected to realize the effective preparation of grain-boundary-free and isotropic MOF glass membrane, which is one of the key goals of porous chemistry in the future. Different types of MOF glasses have been prepared by covering melt-quenching, mechanical or pressure treatment, bottom-up assembly in solution, ionic liquid-assisted melting and sequential perturbation. Nevertheless, the crystallization behavior of liquid and supercooled liquid greatly affects the processing and mechanical, optical, and electrical properties of glass materials, but the mechanism of microstructure evolution during the crystallization process is far from clear. It’s even less clear on systematic study of the crystallization and high-temperature dynamic coordination chemistry for new MOF glass.

Introduction Glassy metal–organic frameworks are emerging types of materials that could combine the modular tunability and high porosity of crystalline metal–organic frameworks (MOF) and the high processability of glassy materials. However, it remains difficult to obtain glassy MOF with high porosity. Thus, an alternative design strategy of embedding crystalline MOF nanocrystals into glassy MOF becomes very attractive to achieve materials with high porosity and liquid-like processability. Glassy materials based on titanium alkoxides are suitable host material for this purpose, which are easy to synthesis at large scale under mild conditions. Also,metal–organic polyhedral (MOP), as the molecular analogue for MOF, are also promising material for synthesizing composite materials. In this report, we developed a series of composite materials made of crystalline MOF and discrete MOP embedded in MOF glasses based on titanium-oxo cluster nodes and alkoxide linkers, and studied their porosity, crystallinity and morphology, which would pave the way for developing composite materials based on MOF glasses.Methods The prototype crystalline MOF, UiO-66, ZIF-8 and HKUST-1 were synthesized through solvothermal condition according to literature reports. The titanium alkoxide glass is made by mixing titanium precursor, titanium isopropoxide and the corresponding alcohol linker in alcohol solvents followed by evaporating the solvent at elevated temperature. To obtain the MOF@MOF glass composite materials, MOF nanocrystals were simply dissolved in the solution mixtures that were used to obtain titanium alkoxide glasses. The MOF@MOF glass composite materials were then washed out with various solvents and activated with super-critical CO2 drying, and then tested for N2 uptake at 77 K to obtain porosity data. The crystallinity of MOF after synthesis were measured by XRD, and the composite materials were studied by SEM. For the composite material using MOP, the hydroxyl functionalized MOP were synthesized in a method similar to literature, and then reacted with titanium precursor to produce the corresponding Ti-MOP material,following by investigation on its surface area.Results and discussion The UiO-66 and HKUST-1 remain the crystallinity unvaried before and after synthesis. The composite material of UiO-66@Ti-PEG-BTM and HKUST-1@Ti-PEG-BTM show surface area of 375 m2/g and 368 m2/g, respectively.Conversely, ZIF-8 loses its crystallinity in the composite material, which has very low surface area. It is speculated that the ZIF-8 structure is unstable with the coordination competition of titanium alkoxide glass precursors. The Ti-MOP composite material also shows higher porosity than that of the MOP itself, showing that such synthetic strategy is promising to produce porous materials.Conclusions We developed a series of optically transparent glassy MOF made from titanium-oxo clusters linked with multi-dentate alcohol linkers, which could be modularly designed and synthesized under mild and environmentally friendly conditions. MOF nanocrystals were succeedingly embedded in the glass to prepare porous composite materials. For UiO-66 and HKUST-1, they retained high crystallinity and porosity in the MOF glasses, whereas ZIF-8 lost its crystallinity. We also developed composite materials based on metal-organic polyhedral and glassy MOF, which also showed high porosity. We therefore developed a new type of MOF glass that could be synthesized under mild condition and showed good compatibility with crystalline MOFs, from which a series of glass–crystal composite material with high porosity were successfully produced. We believe this research provide new opportunities for developing porous composite materials based on glassy MOF.

Introduction Inorganic perovskite quantum dots have attracted extensive attention due to their excellent optoelectronic properties,but the poor stability limits their practical applications. In recent years, perovskite quantum dots in situ crystallization inside robust inorganic glass network (CsPbX3@glass, X=Cl, Br, I) have been evidenced to have superior stability. However, most studies have focused on optimizing the optical properties, while few investigations aiming at carrier dynamics. What’s more, we don't know if interesting phenomenon will happen to the carrier dynamics of perovskite quantum dot glasses, which obtain rare study of mechanism of carrier dynamics, and no halogen mixing are involved before. In this work, the influence of defects and halogen ratios induced by the elevation of crystallization temperature on the carrier dynamics of CsPb(Cl/Br)3@glass nanocomposites are investigated by means of femtosecond laser ultrafast transient absorption spectroscopy (fs-TAS).Methods We synthesized perovskite quantum dot glass by high temperature melting-heat treatment, showing final composition with proportions of (%, in mole) 30SiO-25B2O3-5Al2O3-5ZnO-5CaF2-2PbBr2-4PbCl2-5NaBr-10NaCl-9Cs2CO3. The raw materials are silica (SiO2, Bodie, analytical grade), alumina (Al2O3, Hengxing, 99%), calcium fluoride (CaF2, McLean, 99%), boron oxide (B2O3,McLean, 98%), zinc oxide (ZnO, McLean, 99%), cesium carbonate (Cs2CO3, McLean, 98%), sodium bromide (NaBr, McLean, 99%) and sodium iodide (NaCl, McLean, 99.5%), which are used as raw materials to weigh, mix and grind in agate mortar. The resulting mixture was then placed in a sealed alumina crucible and melted at 1 200 ℃ for 30 min in ambient atmosphere. Subsequently, the glass melt was poured into a copper mold at room temperature. Finally, the obtained bulk glass was treated at 480, 500 ℃ and 520 ℃ respectively for 10 h to induce the precipitation of perovskite quantum dots in the glass, thus obtaining glass ceramics containing perovskite quantum dots. Results and discussion TEM shows that perovskite quantum dots are precipitated in glass. With the increase of temperature of thermal treatment, XRD appears attenuated diffraction peak of perovskite quantum dots and shifts to a small angle, while PL spectrum and absorption peak red shift, which prove that Br– has entered into the lattice. Subsequently, PLQY proved that high thermal treatment temperature could weaken radiation recombination, and the fluorescence attenuation curve shows an unusually long life. The transient absorption spectrum explores the whole carrier dynamics process. First, it is obtained that the hot carrier relaxation lifetimes of perovskite quantum dot glasses treated at 480, 500 ℃ and 520℃ are 140, 190 fs and 210 fs, respectively. Thetemperature related spectrum proves that the hot carrier relaxation becomes slower due to the weakening of electro-acoustic coupling. In the following process of exciton recombination, a new defect state can be observed on the transient absorption spectrum, which may be the reason of the abnormal life of high thermal treatment temperature. Conclusions In summary, with the increase of thermal treatment temperature, the electro-acoustic coupling strength decreases due to the entry of Br– into the lattice. Meanwhile, the hot carrier relaxation takes longer period of time. In addition, due to the high treatment temperature , new shallow level defects that can capture electrons appear, and some electrons can be released back to the conduction band for radiation recombination. This eventually leads to a great improvement of fluorescence lifetime. Understanding these internal mechanisms may provide new guidance for synthesis and application of the investigated material.

Introduction Optical temperature sensor is based on the change of optical properties of materials at different temperatures. It has the advantages of non-contact, high precision, and fast response, and is widely used in industrial and medical fields. However, optical temperature sensors still face some challenges at this stage, such as limited temperature response range of some materials, limited measurement accuracy in complex environments, and high cost. Therefore, improving the temperature measuring range of the sensor,enhancing the anti-interference ability, and reducing the cost, are the important directions of the current research and development of optical temperature sensors. Rare earth ion has a special electronic structure, 5s and 5p orbitals can shield the electron transition in 4f level, so the electronic transition in 4f level is less affected by the external environment, when the external temperature changes, the fluorescence intensity of rare earth ion does not change significantly. The luminescence intensity of CsPbI3 nanocrystalline glass varies greatly by external temperature, and the fluorescence quenching phenomenon is easy to occur at high temperature. In this paper, a fluorescence temperature sensor based on rare earth ion and cesium lead halide perovskite nanocrystalline is used to detect the ambient temperature by the ratio of fluorescence intensity of different luminous centers, which has better sensitivity and does not require complex testing instruments.Methods The glass with the nominal compositions of 41GeO2-25B2O3-8ZnO-3.6PbI2-5.4Cs2O-11NaI-5SrO-1NaF-1.2Tb4O7-yYb2O3 (where y=0, 0.3%, 0.6%, 0.9%, 1.2%, in mole fraction denoted as Y-1, Y-2, Y-3, Y-4, Y-5 respectively), was prepared by melt-quenching method. The Tb3+–Yb3+: CsPbI3 NCs glass was synthesized by subsequent heat treatments. The raw materials were well-mixed and then put into the alumina crucible. The glass batch were melted at 1 200 ℃ for 30 minutes, and the molten glass were poured and pressed into sheets, subsequently annealed to release thermal stresses. These glass sheets were heat treated at various conditions and then optical polished for structural and performance characters.Results and discussion XRD and TEM analysis reveal that the lattice structure is belonged to CsPbI3 NCs, with the incorporation of Tb3+ and Yb3+. Upon excitation with 365 nm, Tb3+ undergoes transitions from 7F6 to 5D3, followed by the emission of distinct wavelengths at 5D4-7F6 (485 nm), 5D4-7F5 (545 nm), and 5D4-7F4 (585 nm), indicating a non-radiation relaxation to the 5D4 level. The energy difference between the 5D4 and 7F6 states in Tb3+ is precisely two times of that in the transition from the state 2F5/2 to the ground state 2F7/2 for excited Yb3+, allowing Tb3+ to absorb a single high-energy photon and to transfer the energy from 5D4 to two Yb3+. Thus two low-energy NIR photons are emitted: Tb3+(5D4)→Yb3+(2F5/2)+ Yb3+(2F5/2). The energy transfer between Tb3+ and Yb3+ is confirmed by the NIR fluorescence spectra. When the glass without heat treatment excited by 365 nm laser, the Yb3+ luminescence peak appears at 950–1 100 nm, confirming that there is an energy transfer process from Tb3+ to Yb3+ since the sole Yb3+ ion cannot be excited by 365 nm laser. Moreover, the infrared luminescence intensity increases with the increase of Yb3+ concentration, indicating that the probability of Tb3+ transferring energy to Yb3+ increases with the increase of Yb3+ concentrations. As the concentration of Yb3+ increased, the fluorescence intensity of Tb3+ also increase in the un-heat-treated glass. Since there are no nanocrystals in the glass matrix, it was speculated that there was a back energy transfer process from Yb3+ to Tb3+. In the presence of CsPbI3 NCs, it is found that the lifetime of CsPbI3 NCs is almost the same before and after adding rare earth ions, indicating that there is no energy transfer between nanocrystals and rare earth ions. The fluorescence lifetime of Tb3+ was found to be enhanced with the increase of Yb3+ concentration, indicating the existence of back energy transfer process from Yb3+ to Tb3+. Because the luminous intensities of Tb3+ and CsPbI3 NCs have different sensitivity to temperature, good self-calibration temperature measurement performance can be obtained by using their luminous intensity ratio with temperature variation. In this work, when Tb3+ is 1.2% (in mole) and Yb3+is 0.3% (in mole), the Tb3+–Yb3+: CsPbI3 NCs glass exhibit the best temperature sensitivity.Conclusions The optical temperature sensor was prepared by using Tb3+ and CsPbI3 NCs with different luminous colors and different sensitivity to temperature. Under the excitation of 365 nm light, Yb3+ emits light, and with the increase of Yb3+ content, the luminous intensity of Tb3+ increases. Since Yb3+ cannot absorb the energy at 365 nm light, there is an energy transfer from Tb3+ to Yb3+. The energy transfer mechanism is as follows: Firstly, Tb3+(5D4)→Yb3+(2F5/2)+ Yb3+(2F5/2) energy transfer process occurs, leading to the emission of 1 020 nm near-infrared light from Yb3+; Secondly, Yb3+(2F5/2)+ Yb3+(2F5/2) →Tb3+(5D4) occurs back energy transfer process, and Tb3+ luminescence is enhanced. Using the fluorescence intensity ratio between the 5D4–7F4 (545 nm) emission of Tb3+ and the emission of CsPbI3 NCs at 680 nm, the temperature sensor with high sensitivity (SA=0.086 K–1, SR=8.63%·K–1, δTmin=0.058 K, 298?403 K) has been prepared, which is promising to be applied in optical temperature sensor.

Introduction In recent years, all-inorganic halide perovskite (CsPbX3, X=Cl, Br, I) quantum dots (QDs) have attracted widespread attention due to their excellent optical and electrical properties. They exhibit high photoluminescence (PL) efficiency, narrow emission bandwidth and tunable emission energy at a wide spectral range. However, the poor stability of CsPbX3 QDs under ambient conditions strongly limit their applications. In this work, CsPbI3 QD-doped borosilicate glasses were prepared by high-temperature melting-quenching followed by heat treatment. ZrO2 is employed as the network modifier, which effectively modifies the local network structure of glass. By optimizing the concentration of ZrO2 and the heat treatment temperature or time, the PL efficiency of the glass can be effectively improved. PL intensity of the QDs glass sample demonstrates high stability, which is almost unchanged after multiple heating and cooling cycles between 293 K and 373 K.Methods The CsPbI3 QD-doped glasses were prepared by high-temperature melting-quenching followed by heat treatment. All raw materials with the designed ratios were accurately weighed and mixed in an agate mortar for 20 min. After the raw materials were thoroughly mixed, they were placed in a covered alumina crucible and transferred to a muffle furnace for melting at 1200 ℃ for 20 min. Afterwards, the glass melt was quenched onto a steel plate and pressed into a glass plate. Finally, the precursor glass were heat-treated at different temperatures (520–550 ℃) for 4 h and at 530 ℃ for different times (2–12 h) to precipitate the CsPbI3 QDs.PL spectra, PL decay curves and thermal stability of glass samples were examined with a FLS 980 fluorescence spectrometer.Optical absorption spectra were recorded by using a UV-3600UV-Vis-NIR spectrometer. X-ray diffraction patterns were recorded by using an X’Pert PRO powder diffractometer. The network structure of glass was analyzed by using a Nicolet 6700 spectrometer and an InVia Reflex Raman spectrometer. The photoluminescence quantum yield (PLQY) was measured with an absolute PLQY measurement system.Results and discussion From the XRD results, as the heat treatment time increases, two diffraction peaks at angles (2θ) of 28.5° and 35.5° become stronger in intensity, corresponding to the (200) and (211) planes of CsPbI3 QDs, respectively. With increasing the ZrO2 concentration, the diffraction peak of (200) crystal plane shifts to a larger angle, which is attributed to the replacement of larger Pb2+ ions by smaller Zr4+. Based on FTIR and Raman spectra characterizations, the network structure of glass is mainly composed of [BO4], [SiO4] and [BO3] units. As the ZrO2 concentration increases, the fraction of tetrahedral network structure formed by [BO4] and [SiO4] units in the glass increases, leading to an increase in the fraction of the three-dimensional network structure of the glass, therefore inhibiting the crystallization of CsPbI3 QDs and reducing the size of QDs. This results in the blue shift of the absorption edge and emission peak wavelength. From the emission spectra, with increasing the ZrO2 concentration, the PL intensity of the glass samples first increases and then decreases. Both the absorption edge and emission peak wavelength show a clear redshift with increasing the heat treatment temperature or time, which is mainly attributed to the increased size of QDs. According to the PL decay curves, as the ZrO2 concentration increases, the PL lifetime of glass gradually decreases; as the heat treatment temperature increases,the PL lifetime of glass gradually increases. Finally, after multiple heating and cooling cycles at 293–373 K, there was no significant decrease in the PL intensity of the glass.Conclusions The CsPbI3 QD-doped borosilicate glass was prepared successfully by high-temperature melting-quenching followed by heat treatment. X-ray diffraction shows that CsPbI3 QDs are precipitated in the glass. With increasing the ZrO2 concentration, the PL intensity of the glass samples first increases and then decreases, and the highest PLQY reaches 32.6%. In addition, the emission peak wavelength and absorption edge show a blue shift, which is attributed to the increased fraction of tetrahedral network structures formed by [BO4] and [SiO4] units in the glass at higher ZrO2 concentrations. Consequently, the increase in the fraction of the three-dimensional network structures of the glass impedes the movement of Cs+, Pb2+ and I–, inhibiting the crystallization of CsPbI3 QDs. After multiple heating and cooling cycles at 293–373 K, there was no significant decrease in the PL intensity of the glass,indicating that Zr4+ doped CsPbI3 perovskite QDs glass has good thermal stability, which may find applications in display, lighting and other fields.

Due to high fluorescence quantum efficiency (PLQY) and narrow half-peak full width (FWHM), all-inorganic CsPbBr3 backlight display sources. Perovskite quantum dots glass, possessing excellent luminescence properties of quantum dots and physical/chemical stability of glass, has attracted wide attention. However, during its preparation process, serious component volatilization would occur since the melting temperature of Cs-Pb-X glass is as high as 1 000 ℃, and it is difficult to control grain size and distribution; therefore, the experimental repeatability becomes a problem. The currently reported CsPbBr3 quantum dot glass is still difficult to achieve a peak wavelength close to the Rec.2020 standard of 525?535 nm high-purity green narrow band luminescence.In this work, based on an in-situ growth method, CsPbBr3 quantum dots-porous glass composite (CPB-PG for short) was prepared by using porous glass as template. Since the growth of quantum dot is limited by the pore channels of the PG, the composition/structure of the composite material has good controllability. Varying the process conditions of heat treatment for phase separation, acid leaching and alkali washing, the pore size distribution of CsPbBr3 quantum dots in CPB-PG can be manipulated. The maximum full width at half maxima (FWHM) of CPB-PG is merely 18 nm, enabling ultra-pure green light emission that is essential for wide-gamut backlight display (the color coordinates get close to the Rec.2020 standard). A white light-emitting diode (LED) prototype device was constructed by coupling green CPB-PG, red K0.42Cs0.58Pb(Br1.5I1.5) quantum dot glass powders and InGaN blue chip; upon driven at 20 mA current, the device yields white light with luminous efficacy of 30 lm/W, correlated color temperature of7?710 K, color rendering index of 75.8, and covering 96% color gamut under the Rec.2020 standard.Methods The composition of the parent glass is 69SiO2-24B2O3-7Na2O. The prepared parent glass is heat treated at a temperature slightly higher than glass transition temperature for a certain time to produce nanoscale phase separation. The alkali-rich borate phase was dissolved by acid leaching, while the silicon-rich phase was retained, thus forming nanoscale pores. The size of pore size caused by acid leaching can be controlled by adjusting the temperature and time of heat treatment. By further alkali washing out, the silica material accumulated in the rigid pores of the silicon-rich phase skeleton can be removed, so as to expand the volumes of pores.CsPbBr3 quantum dots are not synthesized in advance. CsBr and PbBr2 are dissolved in water, and then add PG powder. Cs+, Pb2+, Brwill be adsorbed in the PG glass channels. After drying the aqueous solution, CsPbBr3 underwent in-situ crystallization in the pore channels to obtain the CPB-PG composite.Results and discussion XRD analyses demonstrate the precipitation of CsPbBr3 nanocrystals from glass matrix. The crystalline phase is dependent on the feeding amount of CsBr and PbBr2. When the feeding amount gets higher than 0.12 mmol, the Cs4PbBr6 impurity phase will precipitate out. Careful TEM analyses were performed to reveal the microstructural features of the precipitated CsPbBr3 nanocrystals. Interestingly, one can see some twin crystals, i.e., two crystals form a mirror-symmetric orientation relationship along a crystal plane. The formation of twins helps to stabilize the phase structure. The crystal size of CsPbBr3 gradually increases in the following the sequence: CPB-PG1With the increase of crystal size, the luminescence peak redshifts: 514 nm→527 nm→532 nm, which is related to the quantum confinement effect. The half-peak full width (FWHM) of CPB-PG2 sample is the narrowest, merely 18 nm. The luminescent dynamical studies reveal that the luminescent decay curves can be well fitted by the double exponential function of equation, where the fast (τ1) and slow (τ2) lifetime components can be determined. τ1 gets close to the lifetime of colloidal CsPbBr3 quantum dots reported in the literature (5?10 ns), and can be attributed to the exciton recombination fluorescence transition process affected by non-radiative relaxation process. τ2 results in the delay of fluorescence decay, which can be attributed to the trapping effect of shallow trap level. It was found that with the increase of crystal size, τ1 tends to decrease, indicating that the number of defects leading to fluorescence non-radiative relaxation may increase; meanwhile, τ2 increases, indicating that the associated shallow trap level defects also increase. It can be inferred that when CsPbBr3 melted and recrystallized in PG glass with large pore size, the quantum dot components may be more easily volatilized through pores, resulting in more vacancy defects.Benefiting the narrow FWHM of CPB-PG2, the CIE coordinate of (0.142, 0.782) gets close to the green coordinates defined by the standard Rec. 2020 standard (0.170, 0.797). Upon coupling the glass with blue LED chips, the electroluminescence is very bright.In order to verify the potential application of CPB-PG for w-LED , the CPB-PG2 powders, K0.42Cs0.58Pb(Br1.5I1.5) quantum dots glass powder and silica gel were mixed together, and then coated on the surface of InGaN 450 nm blue LED chip, whereupon w-LED prototype device was constructed. The constructed W-LED yields luminous flux of 1.58 lm, luminous efficiency of 30 lm/W, CCT of 7 710 K, CRI of 75.8, color coordinates of (0.284, 0.358), and covering 96% color gamut under the Rec. 2020.Conclusions Using porous glass as template, CPB-PG composites were prepared by impregnating porous glass powder in halide salt solution, CsPbBr3 nanocrystals in-situ precipitate out in the pore channels during the succeeding heating and cooling processes.The crystal size of CsPbBr3 can be adjusted by varying the pore size of porous glass under different heat treatment, acid leaching and alkali washing conditions. The prepared CPB-PG composite emits green light in a narrow band with a FWHM of 18 nm,corresponding to a quantum efficiency of 56%. Fluorescence kinetic analysis revealed that there are structural defects in CPB-PG,greatly affecting the fluorescence properties. The constructed w-LED prototype device can cover approximately 96% color gamut under the Rec. 2020 standard, demonstrating a potential application in LCD backlight displays.

Cesium lead halide perovskite quantum dots (CsPbX3) have emerged as pivotal materials in the realm of optoelectronics, owing to their exceptional properties. However, traditional synthesis methods often yield quantum dots (QDs) with poor durability, rendering them susceptible to degradation under various environmental impact such as light, oxygen, humidity, and high temperatures. This inherent instability hampers their long-term viability across diverse applications.1) Stability Challenges and Solutions When exposed to adverse conditions, colloidal CsPbX3 QDs swiftly deteriorate, leading to a decline in their photoluminescence (PL) emission performance. To mitigate this issue, diverse strategies have been devised,focusing on enhancing the long-term durability of QDs. Such as surface ligand modification, mesoporous structure encapsulation, core-shell structures, and composition engineering: Despite these advancements, challenges persist, particularly regarding the efficacy of surface protective layers. Existing methods often yield structures with insufficient density, leading to compromised long-term protection. Additionally, the stability of silicon dioxide, commonly utilized in wet chemical methods, remains a concern. The protective layer structure formed by these methods on the surface of PQDs is not dense, and the silicon dioxide prepared by wet chemical methods is also unstable, making the long-term protection of PQDs insufficient against external environmental factors.2) Quantum Dots Glass: A Solution for Long-Term Stability Inorganic glass is considered an excellent medium to prevent QDs degradation and improve their thermal stability. For example, there have been reports on the growth of II-VI and IV-VI QDs in glass,such as ZnO, ZnS, ZnSe, CdS, CdSe, PbS, and PbSe. Studies have found that glass has chemical and physical stability, as well as high mechanical strength, high temperature resistance, and chemical corrosion resistance. Glasses can prevent QDs from being eroded by the surrounding environment, allowing QDs to be evenly distributed in the glass matrix without aggregation, and the size of QDs embedded in glass is easy to control. Hence, a novel approach to address the stability issues of CsPbX3 QDs involves embedding them within a structurally dense and performance-stable inert glass matrix, creating what is known as “quantum dots glass.” This innovative composite material effectively circumvents the drawbacks associated with poor stability in standalone QDs while preserving their exceptional performance characteristics.3) Expanding Horizons with Quantum Dots Glass Quantum dots glass not only offers enhanced stability but unlocks new possibilities in optoelectronic applications as well. Beyond addressing stability concerns, quantum dots glass holds promise for diverse applications, including:Optical Fiber Fabrication: Leveraging the properties of quantum dots glass opens avenues for the fabrication of high-performance optical fibers, facilitating advancements in telecommunications and photonics.Optoelectronic Functional Materials: By integrating quantum dots glass into optoelectronic devices, novel functionalities and performance enhancements can be achieved, paving the way for next-generation technologies.Summary and prospects In this paper, we delve into the preparation methods, crystallization, and emission mechanisms of cesium lead halide quantum dots glass. Emphasis is placed on the stability challenges encountered in practical applications, including temperature variations, light exposure, and humidity. Significant strides in addressing these challenges are highlighted, offering insights into potential avenues for future research endeavors.At the same time, quantum dots glass retains the excellent optical performance of CsPbX3 PQDs. Studies have shown that enhancing the rigidity of the glass network structure, such as replacing GeO4 tetrahedra with SiO4 tetrahedra, helps enhancing the water resistance of quantum dots glass. Additionally, using tellurite-based glasses with a higher density to encapsulate QDs or doping with high atomic number rare earth ions, such as Gd3+ and Lu3+, contributes to improve the material's radiation resistance. However,the understanding of the damage mechanism of PQDs glass under high energy beam irradiation, the thermal erasure mechanism, and the PL quenching mechanism of quantum dots glass at high temperatures is not deep enough at present. There is an urgent need for more direct experimental and theoretical research.The development of quantum dots glass represents a significant leap forward in enhancing the long-term stability of CsPbX3 QDs. With the in-depth study of the synthesis process of quantum dots glass, by designing rational glass compositions and regulating the precipitation process of CsPbX3 PQDs, comprehensive optimization of optical performance can be achieved. By harnessing the unique properties of both QDs and glass matrices, this composite material not only overcomes stability limitations but also opens new frontiers in optoelectronics. It provides new perspectives for improving the current state of quantum dots glass and is expected to play a crucial role in various optical fields. Moving forward, continued research and innovation in this field hold immense potential for revolutionizing optoelectronic device design and functionality.

Inorganic perovskite nanocrystals exhibit superior thermal stability and higher quantum yields compared to organic-inorganic hybrid perovskites. Additionally, perovskite nanocrystals have gained significant attention in fields such as solar cells, low-threshold lasers, light-emitting diodes (LEDs), and photodetectors, owing to their excellent tunable luminescent and optoelectronic properties. As a kind of nanocrystal with excellent photoelectric properties, CsPbX3 can achieve tunable emission in the whole visible spectral region by means of compositional alloying and quantum size effect. However, all-inorganic CsPbX3 perovskite nanocrystal still faces challenges in terms of poor stability and the toxicity of lead, which limits its application. Various strategies have been proposed to improve its resistance against environmental erosion, including surface modification, polymer encapsulation, and in-situ crystallization within inert glass matrices. Among them, embedding nanocrystals into inert glass matrices has been proposed to enhance their stability and demonstrate excellent heat resistance and resistance to intense light irradiation. However, traditional oxide glass is prepared under high-temperature open environments, leading to the volatilization of some glass components and the decomposition of perovskite nanocrystals. It results in unclear composition of the prepared glass and poor sample reproducibility. On the other hand, in response to the environmental toxicity of lead-based perovskites, non-toxic metals such as Sn, Bi, and Ge were employed for the substitution for Pb. Tin-based perovskites, in particular, have similar crystal and electronic structures to lead-based perovskites and exhibit fascinating near-infrared luminescence. By controlling the composition and quantum size, the emission spectra of CsSnX3 perovskites can be tuned from visible light to approximately 1 μm in the near-infrared spectral region, which can not be achieved in lead-based perovskite materials. However, due to the high sensitivity and easy oxidation of metastable Sn2+, the synthesis of CsSnX3 perovskite usually requires more stringent conditions, making the preparation procedure more difficult.Chalcogenide glassy flux method is introduced by using chalcogenide-based materials with good glass-forming ability, such as GeS2 and Sb2S3, as fluxes. Metal halides like CsX, SnX2, or PbX2 are dissolved in such chalcogenide fluxes, and the resulting mixture is melted and rapidly cooled to form glass. Subsequent heat treatment is applied to achieve controllable precipitation of the dissolved metal halides. This method allows for the formation of perovskite nanocrystals with arbitrary halide compositions within the transparent glass matrix, and meanwhile prevents the loss of metal halide precursors, therefore improving the reproducibility. The controllable crystallization mechanism of chalcogenide glass-ceramics with the composition of 79.2GeS2-15.8Sb2S3-5CsSnBr3 was investigated. The base samples were subjected to thermal treatments at 290 ℃ for 13, 20, 60 h, and 100 h. The variation of particle size and quantity of precipitated CsSnBr3 nanocrystals was observed by SEM and plotted as a function of the heat-treatment conditions. It was found that it exhibited power-law variations with time, following the Lifshitz-Slyozov-Wagner (LSW) theory. The phenomenon of increasing crystal size and decreasing crystal quantity during the heat treatment process was explained using Ostwald ripening theory. As the heat treatment progresses, the continuous growth of larger crystals consumes at the expense of smaller crystals.Eventually, when all crystal sizes became similar, this dissolution-growth behavior reach equilibrium.Summary and prospects Inorganic perovskite nanocrystals have attracted significant attention due to their tunable emission wavelength and excellent optoelectronic properties. By utilizing glass flux method, controlled precipitation of perovskite nanocrystals such as CsPbX3 and CsSnX3 has been successfully achieved in sulfur-based glass. Tunable photoluminescence ranging from visible to near-infrared has been realized. The crystallization behavior of these perovskite nanocrystals in sulfur-based glass was revealed to follow the Ostwald ripening mechanism, allowing for controllability of nanocrystal size, crystal phase, and crystallinity. However, further research is required to investigate the characteristics of perovskite nanocrystals in sulfur-based glass, e.g., the relationship between their size, luminescence intensity, composition variations, and luminescence efficiency. Additionally, as a semiconductor material, sulfur-based glass holds potential application in electroluminescence compared to other substrate materials.

The typical all-inorganic metal halide perovskite CsPbX3 (X=Cl, Br, I) is widely used in the field of optoelectronics due to its advantages such as tunable spectra, good monochromaticity, and high photoluminescence quantum efficiency. However, the structural instability of perovskite crystals is one of the inevitable problems affecting their practical applications.Perovskite nanocrystal glass, with its unique advantages such as tunable emission wavelength in the visible light spectrum, ultra-high stability, high photoluminescence quantum efficiency, and good monochromaticity, is widely used in frontier areas such as optical storage, Micro-LEDs, and ultra-high-resolution displays. However, there are still some issues with perovskite nanocrystal glass in applications. For example, the dense glass network structure limits the migration and growth of nanocrystals, resulting in lower quantum efficiency compared to nanocrystals in colloids. To optimize quantum efficiency, appropriate B-site substitution ions can be selected to reduce the toxicity of Pb and to improve the stability of perovskite nanocrystals. The heat treatment process reduces the energy barrier of the glass network, promotes the migration and enrichment of perovskite ions, and regulates the glass network structure to affect the migration and aggregation of ions, thereby affecting the nucleation and growth of perovskites. Additionally, self-crystallizing glass has relatively low energy barriers and reduces energy consumption during the heat treatment process. These methods of controlling crystal quality provide opportunities for improving the quantum efficiency of perovskite nanocrystal glass.Furthermore, controlling the size and composition of perovskite nanocrystals can achieve tunable emission wavelengths. In addition to the above methods, ultrafast lasers, with features such as energy accumulation due to multiphoton absorption, micro-explosions induced by plasma thermal expansion, and rearrangement of glass frameworks, can induce local crystallization of glass, enabling direct redistribution of regional elements and design of localized chemical compositions. These optimization measures make full-spectrum coverage possible, which benefits significantly for color rendering, lighting efficiency, and energy savings.Perovskite nanocrystal glass exhibits excellent stability while maintaining its excellent optical properties, demonstrating tremendous potential in the field of optics. Through encapsulation in a glass matrix, the stability of perovskite nanocrystals is enhanced, ensuring long-term stability and high efficiency performance in harsh environments. The fundamental mechanisms of controlling the composition of perovskite crystals and emission wavelengths through heat treatment, ultrafast laser writing, and other methods are analyzed thoroughly. Finally, the potential applications and development prospects of perovskite nanocrystal glass in fields such as LEDs and optical storage are summarized and forecasted.Summary and prospects Encapsulating CsPbX3 NCs within a glass matrix has enhanced the stability of nanocrystals, enabling efficient and long-term luminescence in optical applications. To improve the PLQY and to tune the emission wavelength of CsPbX3 NCs@glass, methods such as B-site substitution, modification of glass components, optimization of heat treatment processes, and improvement of laser processing parameters can be employed to regulate their luminescent properties. The resulting materials have been widely used in fields such as optical storage, LED displays, photocatalysis, and X-ray detection. However, the quantum efficiency of CsPbX3 NCs@glass reported in most literatures is generally lower than that in colloidal nanocrystals since the dense glass network hinders the diffusion of CS+, Pb2+, X?, making direct modification and surface passivation of perovskite nanocrystals challenging. To unlock the potential applications of CsPbX3 NCs@glass in optical fields, the other considerations are suggested to keep in mind, that is, to reduce the toxicity of Pb and to enhance the quantum efficiency of blue-band of CsPbX3 NCs@glass. The strategies are hopeful to achieve technological leap in this area.

All-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite quantum-dots (PQDs) glass exhibits exceptional optical and electrical properties, such as high quantum yield (QY), high purity, tunable emission wavelength, high defect tolerance, and fast charge carrier diffusion rates, making them promising for a wide range of applications in photovoltaics, light-emitting diodes (LEDs), photodetectors, lasers, and other optoelectronic devices. However, perovskite quantum dots are prone to degradation due to their ionic to enhance their stability and maintain the high luminescence efficiency, researchers have begun to incorporate these CsPbX3 quantum dots into high-transparency glass substrates with excellent thermal, mechanical, and chemical stability. In recent years, many researchers have successfully synthesized PQDs embedded glass systems such as silicate, germanate, tellurite, phosphate, and borate, and have applied the synthesized material in fields of optical sensing, X-ray imaging, lasers, optical information storage, and optical anti-counterfeiting.Common methods to prepare PQDs embedded glass include melt-quenching method, mechanical stress-induced method, and water-induced methods. Both thermal treatment methods fail to localize crystallization, while stress- or water-induced crystallization detrimentally affect the glass structure and introduce toxicity from surface heavy metal Pb, significantly limit their application prospects. Fortunately, ultra-short pulse laser, femtosecond laser processing of transparent materials, has been demonstrated as an effective means to construct three-dimensional photonic device structures. This facilitates the materials to be hopefully applied in nonlinear optics, optical data storage, and nanophotonics. Femtosecond laser interacts with transparent materials via multiphoton absorption, circumventing the need to consider material absorption or introduce new absorption centers, and the highly localized energy of focused ultra-short pulse laser is achieved. The high spatial resolution of this processing is realized by the rapid redistribution of atoms at the laser focus induced by successive nonlinear optical processes. This technique has been successfully applied to introduce microcracks, alter micro-zone refractive indices, and form nanocrystals. Compared to traditional methods for preparing perovskite quantum dots, femtosecond laser is more suitable for precipitating perovskite quantum dots within transparent glass materials.This article provides a comprehensive overview of the progress made in studying the crystallization and optical properties of CsPbX3 PQDs embedded glass under femtosecond laser irradiation, and offers new ideas and insights for future research and application of PQDs embedded glass regulated by femtosecond laser.Summary and prospects Coating PQDs in transparent glass media has greatly enhanced stability while maintaining excellent optical properties, so as to attract widespread attention from researchers in recent years. Utilizing femtosecond laser technology enables the manipulation of crystallization behavior of perovskite quantum dot glass in three-dimensional space, which holds significant implications for three-dimensional optical information encryption and storage. Additionally, the interaction between femtosecond laser and PQDs embedded glass enables reversible luminescence, laser emission, polarization, and long persistent luminescence properties, significantly expanding the application domains of PQDs embedded glass. However, many challenges still exist in the direction of femtosecond laser and PQDs embedded glass that researchers need to explore and resolve. The challenges are: how to use femtosecond laser to fabricate perovskite waveguides or single crystals in glass, potentially endowing inorganic glass with optoelectronic properties; how to design and to fabricate lead-free perovskite glass using femtosecond laser to further investigate its optical applications while maintaining non-toxic high optical performance; how to utilize femtosecond laser as pump sources to achieve laser output from PQDs embedded glass at room temperature; how to design specific optical devices and principles to further reduce the size of PQDs written inside glass to the nanometer scale using femtosecond laser, which is expected to greatly enhance the three-dimensional optical information storage capacity, etc. It is believed that in the near future, PQDs embedded glass under the influence of femtosecond lasers will lead us into a brand-new optoelectronic world.

In recent years, the pollution of radionuclides to water is becoming more and more serious with the rapid development of nuclear technology. The expansion of activities, such as uranium mining, nuclear research, weapon manufacturing,and nuclear power generation will produce many radioactive isotopes. Among these radionuclides, uranium (VI) (U(VI)) poses a great threat to the biosphere due to the enhanced chemical affinity with organic ligands, radioactive toxicity and long half-life.Therefore, it is necessary to develop a technology to reduce or recover U(VI) in wastewater for decreasing the risk of U(VI) pollution to the environment and realizing the resource utilization of U(VI). The adsorption method has been widely studied due to the relatively mature technology, good repeatability of adsorbent, high adsorption efficiency, low cost and easy operation. Titanium dioxide (TiO2) is considered one of the best adsorbents due to the low cost, non toxicity and high chemical activity. However, the agglomeration of TiO2 particles will reduce the number of active sites per unit area, leading to a weakened adsorption ability for U(VI). An effective strategy to improve the adsorption ability is to prevent the aggregation of TiO2 particles and improve the surface activity of TiO2. Therefore, in this work, iron doped nano-TiO2 materials (Ti–Fe composites) were prepared by the sol gel method,aiming to prevent the aggregation of TiO2 particles in use and improve the adsorption performance.

Introduction In recent years, the pollution of radionuclides to water is becoming more and more serious with the rapid development of nuclear technology. The expansion of activities, such as uranium mining, nuclear research, weapon manufacturing, and nuclear power generation will produce many radioactive isotopes. Among these radionuclides, uranium (VI) (U(VI)) poses a great threat to the biosphere due to the enhanced chemical affinity with organic ligands, radioactive toxicity and long half-life. Therefore, it is necessary to develop a technology to reduce or recover U(VI) in wastewater for decreasing the risk of U(VI) pollution to the environment and realizing the resource utilization of U(VI). The adsorption method has been widely studied due to the relatively mature technology, good repeatability of adsorbent, high adsorption efficiency, low cost and easy operation. Titanium dioxide (TiO2) is considered one of the best adsorbents due to the low cost, non toxicity and high chemical activity. However, the agglomeration of TiO2 particles will reduce the number of active sites per unit area, leading to a weakened adsorption ability for U(VI). An effective strategy to improve the adsorption ability is to prevent the aggregation of TiO2 particles and improve the surface activity of TiO2. Therefore, in this work, iron doped nano-TiO2 materials (Ti–Fe composites) were prepared by the sol gel method, aiming to prevent the aggregation of TiO2 particles in use and improve the adsorption performance. Methods Tetrabutyl titanate (C16H36O4Ti, 98%), ethanol (C2H6O, 99%), ethylene glycol ((CH2OH)2, 99%), hydrochloric acid (HCl, 36%), anhydrous ferric chloride (FeCl3, ≥ 99.9%), triazo arsine (III)(C22H18As2N4O14S2, 99.9%) and uranyl nitrate (UO2(NO3)2·6H2O, 98%) were purchased from Aladdin's reagent.TiO2 and Ti–Fe composites were synthesized by sol gel freeze drying technology. Firstly, 3 mL of C16H36O4Ti was added to 15?mL of C2H6O to obtain a transparent mixture. Secondly, FeCl3 (100 mg) was added to the transparent mixture with rapid stirring for 30 min to evenly disperse FeCl3 in the solution. In the third step, 5 mL (CH2OH)2 was added to the mixture with stirring for 7 min to obtain a uniform sol. The sol was quickly transferred into the glass bottle, let stand to form a uniform Ti–Fe composite gel, which was aged at room temperature for 24 h. Put the aging Ti–Fe composite gel in distilled water to remove the excess C2H6O and (CH2OH)2 through solvent exchange. Finally, Ti–Fe composite was obtained by freeze-drying. The effects of pH, ionic strength, ion species, contact time, initial U(VI) concentration and dosage of adsorbents on the adsorption of TiO2 and Ti–Fe composite for U(VI) were investigated through batch experiments. 10 mg of adsorbent was added to a glass container having 100 mL of U(VI) solution. The container was then placed in a water bath at a constant temperature with stirring at 300 r/min for 3 h. After adsorption, the solid phase was separated by polyethersulfone mem-brane (0.45 μm). The UV–Vis spectrophotometer was applied for U(VI) concentration measurement using arsenazo (III) as the colorant.Results and discussion XPS spectra indicated that Ti–Fe composite was successfully prepared due to the presence of iron element.The anatase crystallinity of TiO2 and Ti–Fe composite was poor, which was mainly related to the amorphous structure of Ti—O—Ti.SEM images and the analysis of specific surface area further demonstrated that doping iron enhanced the dispersibility of TiO2 materials, which could provide more available active sites for U(VI) adsorption.The adsorption properties of TiO2 and Ti–Fe composite for U(VI) were compared. At the optimum pH value, the adsorption behavior of Ti–Fe composite for U(VI) reached the equilibrium within 60 min, the adsorption efficiency was 94.5% and the maximum adsorption capacity was 672.9 mg/g. Moreover, the remarkable adsorption efficiency of Ti–Fe composite was above 90% even after five cycles and the adsorption efficiency was relatively high in the solution with different coexisting ions. The adsorption isotherm and kinetic models showed that the adsorption of U(VI) on Ti–Fe composite was a single homogeneous chemisorption. It was worth noting that the adsorption performance of TiO2 for U(VI) was significantly enhanced, which was mainly due to the significantly enhanced dispersion, oxygen vacancy filling, oxidation-reduction effect and inner-sphere surface complexation of TiO2 after doping with iron.Conclusions Ti–Fe composite with excellent U(VI) removal ability were prepared by sol?gel freeze-drying technique. Under the condition of pH=4, T=298 K, the adsorption efficiency for U(VI) by Ti–Fe composite was 94.5% (m/V=0.1g /L, c0=10 mg/L). The experimental adsorption capacity was 672.9 mg/g (m/V=0.1 g/L, c0=180 mg/L). After 5 cycles, the adsorption efficiency of U(VI) by Ti–Fe composite remained above 90%. Ti–Fe composite exhibit excellent adsorption properties even in complex water environments, which might be due to the synergistic effect of oxygen vacancy filling, oxidation-reduction effect and inner-sphere surface complexation. In general, Ti–Fe composite possessed a promising application in U(VI)-containing wastewater treatment.

Introduction Silica aerogel is a novel nanostructured material, and the exceptional transparency makes it invaluable for applications in photothermal conversion, energy storage, building insulation, solar collector, and advanced optical devices. Silica aerogels could serve as the key component of devices in field of radiation detection due to their exceptionally high transmittance. Although numerous studies have addressed the transparency of silica aerogels, there is a notable gap in research for regarding the relationship between the transmittance and aerogel thickness. Consequently, it still remains a challenging problem for effectively maintaining high aerogel transmittance (approaching 80% at 550 nm) at a specific thickness (approaching 10 mm). In this work, the titration experiments were first concluded to identify optimal synthesis parameters, which was beneficial to investigate the phase demarcation points in the ternary phase diagram. Subsequently, according to the optimal parameters, highly transparent silica aerogels were prepared by using the sol-gel method. Additionally, a comprehensive examination of silica aerogels, including density, microstructure and transmittance, was conducted in detail.Methods The synthesis of silica aerogels was conducted through the sol-gel method. The following materials were employed: Tetraethoxysilane (TEOS, 98%) as the silica precursor, ethanol (EtOH) as the solvent, water (H2O) as the hydrolysis reactant, and ammonium hydroxide solution (NH4OH, 25%) as the catalyst, respectively. The alcogels were dried by ethanol supercritical drying to obtain transparent silica aerogels. The morphology and microstructure of silica aerogels were observed by a Zeiss EVO-50 XVP scanning electron microscope (SEM). The UV-Vis spectrophotometer was used to test the aerogel transmittance in the wavelength range of 500–800 nm. The specific surface area of aerogels was calculated by Bruno-Emmett-Teller (BET) method. Under the relative pressure p/p0=0.99, the total pore volume was calculated by nitrogen adsorption-desorption isotherm. The related pore size distribution was obtained by Barret-Joyner-Halenda (BJH) method.Results and discussion The solvent titration experiment data was normalized and subsequently used to construct the ternary phase diagram. The ternary phase diagram clearly demonstrated the phase transition boundary, single-phase region and multi-phase region, respectively for three solvents at room temperature. Thus, the ternary phase diagram could be employed to predict whether any mixture of three solvents results in a transparent solution, regardless of its proportions. The silica aerogels were prepared by using the parameters of ternary phase diagram. Specifically, it was seen that the higher initial transmittance the sols had, the similarly higher transmittance the aerogels also had. Moreover, the related transmittance of the sol-gel-aerogel system in the single-phase region demonstrated the highest value (~80.3%), which was better than that (~74%) on the phase transition boundary. The silica aerogel with the higher transmittance could be prepared in the single-phase region, and it provided a new idea for further study around the single-phase region of ternary phase diagram.In order to manipulate the phase boundary point for accessing the single-phase transparent interval, the ethanol volume fraction in the mixture increased along the extension of the selected phase boundary point. It illustrated that the aerogel transmittance first rose with the increase of ethanol volume fraction. However, it decreased with the excessive ethanol. With an increase of ethanol volume fraction, the average particle size of silica aerogels decreased first and then increased. Moreover, the relationship between average particle size and transmittance were further established. The average particle size had a linear relationship with the transmittance of silica aerogels, meaning that the smaller the average particle size was, the larger the aerogel transmittance was. Furthermore, the skeleton particle boundary size of Rayleigh scattering and Mie scattering could be calculated and the corresponding particle boundary size at a wavelength of 550 nm was calculated to be 57 nm. The aerogel transmittance at a wavelength of 550 nm was further compared with the cumulative frequency of skeleton particles whose size were the smaller than the boundary one (~57 nm). It could be concluded that the aerogel transmittance had a certain linear correlation with the cumulative frequency. Obviously, the largest cumulative frequency (~94.68%) corresponded to the highest transmittance (the transmittance of sample C3 was 79.6%), while the lowest cumulative frequency (~83.05%) corresponded to the lowest transmittance (the transmittance of sample C5 was 69.5%).Conclusions According to the ternary phase diagram, the highly transparent silica aerogels were precisely prepared by using the optimal synthesis parameters. The higher initial transmittance of the sols induced a higher transmittance of the aerogels. Furthermore, the smaller the average particle size, the larger the transmittance of silica aerogels could be, which was attributed to the larger cumulative frequency of particle size smaller than 57 nm due to the suppression of Mie scattering opaque effect. Besides, the higher pore size meant the lower aerogel transmittance, which was caused by the stronger light scattering effect. In a word, the highly transparent silica aerogel with transmittance (~80.3% at 550 nm) at a specific thickness (~10 mm) was successfully fabricated by the sol-gel method in the single-phase region, which would be satisfied with practical application requirements in Cherenkov radiation detector.

The sol–gel technology is an interdisciplinary field combining materials science and chemistry. It utilizes highly active chemicals as precursors, taking part in chemical reactions and treatment such as hydrolysis, polymerization, gelation, etc.. Solid product are often achieved by specific drying, heat treatment, or other processes/conditions. As an advanced wet-chemical preparation method, sol–gel technology finds widespread applications in the fabrication of zero-dimensional to three-dimensional nanomaterials, bulk materials, thin film coatings, fiber materials, etc. Materials obtained through this method exhibit superior characteristics and properties compared to those obtained through traditional methods. Most sol–gel processes are conducted at low temperatures, resulting in lower reaction temperatures compared to traditional methods. Materials prepared using this method possess inherent advantages in terms of chemical homogeneity, doping uniformity, and product purity. Moreover, the design of the early-stage preparation process enables the synthesis of multi-component materials with multi-phase.Over the past two decades, China has made great progress in the research and application of sol–gel technology. Scientists have developed a wide range of methods for preparing novel materials using sol–gel techniques. These materials have been applied across various domains including optics, electronics, sensing, catalysis, energy storage, pharmaceuticals, separation, and many others. These achievements typically involve the preparation of advanced materials with novel functionalities or enhanced performance using sol–gel processes. Through this overview of the latest developments in the sol–gel academic field, one can appreciate the comprehensive research and significant contributions made in China.The development of sol–gel technology can be traced back to the mid-19th century. As the 20th century progressed, the method of using gelation to prepare solid materials began to receive increased attention from researchers. More and more scholars began to focus on sol–gel technology, proposing various methods for preparing materials in various forms. These methods have found applications in multiple domains such as electronic devices, catalysis, energy, metal corrosion protection, optics, and others. In 1981,the First International Workshop on Glasses and Glass Ceramics from Gels was held in Padova, Italy, marking the rapid development phase of sol–gel technology. Sol–gel research in China also began in the 1980s, when many research institutions started extensively to work on sol–gel technology during this period. In 1990, the inaugural "National Conference on Sol–Gel Science and Technology" was held at Zhejiang University, marking the beginning of the sol–gel era in China. Subsequently, this conference has been held every 2 to 3 years, providing a high-quality platform for academic exchange in the field of sol–gel technology in China. In 2008, the Sol–gel Committee of the Chinese Ceramic Society was established, signifying the formal establishment of a professional association for sol–gel technology in China. The Sol–gel Committee of the Chinese Ceramic Society not only actively organizes academic activities within China but strives to promote communication with the abroad academic society and to organize international conferences as well. From August 28 to September 2, 2011, the 16th International Sol–gel Conference was held in Hangzhou, China. This marked the first time that China hosted this prestigious academic conference in the sol–gel field, receiving high praise from the international sol–gel community.In recent years, Chinese research institutions and scholars have published an avalanche of papers in the field of sol–gel. Over the past decade (2014–2023), there has been a steady increase in global publications related to the sol–gel field, with a total of 128 627 papers. Among these, articles authored by Chinese researchers accounted for 32.5% of the global output, with this proportion reaching 50% in the year 2022. This paper focuses on highlighting some research achievements in the preparation of nano-powder materials, fiber materials, and functional coatings using the sol–gel method. It also discusses the application in energy storage, catalysis, electromagnetic shielding, thermal conductivity, luminescence, and thermal insulation.With the rapid development of sol–gel technology, the achievements of the Chinese sol–gel academic community have also propelled its industrial development. Many new materials developed through sol–gel processes have entered the industrial application stage and become part of people's daily lives. The mass production of nano oxides and ceramic powders using the sol–gel method is well developed in China. It is applied in various fields such as semiconductors, optical component polishing materials, functional coatings, reinforcement of polymer materials, and catalytic carrier materials. Sol-gel technology has also been widely applied in the production of functional coating materials, used in applications such as anti-corrosion coatings for metals, optical coatings, and more.Summary and prospects Since the concept of sol–gel was proposed, sol–gel technology has demonstrated tremendous potential in various fields, ranging from materials science to life sciences and environmental engineering. It is evident that China has made remarkable progress in both academic and industrial application of sol–gel technology, bringing it into a new stage of vigorous development. By reviewing and summarizing the development of sol–gel technology in China, one can clearly see the remarkable achievements and groundbreaking progress made in this field. Chinese researchers have played a key role in this process, driving the continuous evolution of this technology. China's successful experiences in sol–gel technology are not only evident in scientific research but also widely applied in industrial manufacturing and sectors. Looking ahead, sol–gel technology is expected to focus on several key development directions in the future. In fundamental research, the study of sol–gel technology can focus on the functional design and construction of precursors, their combination with functionalized ionic solvents, and the construction of micro-reactive zones. In terms of industrial technology, sol–gel technology shows promising prospects in the preparation of spherical powders at different scales, deep ultraviolet treatment, non-high-temperature treatment processes such as solvent thermal treatment, as well as aerogels/hydrogels. Sol–gel technology in China holds vast potential for development. We anticipate that sol–gel technology will be widely applied in more fields, especially playing a more crucial role in addressing major issues such as energy, environment, and health. In the future, it will continue to make outstanding contributions to human well-being and technological advancement.

Carbon aerogels are one of the most promising materials for high-temperature thermal insulators under inert atmosphere owing to their properties of low density, low thermal conductivity, ultra-high temperature resistance in inert atmospheres, and high infrared specific extinction coefficient. At present, there have been some studies on carbon aerogel thermal insulations at home and abroad,but most of them focus on the improvement of mechanical, antioxidant and ablation resistance properties, the simplification and low cost of the preparation process, as well as the ultralight and super-elastic properties of carbon aerogel. There is few study about how to further optimize the high-temperature thermal insulation performance of carbon aerogel thermal insulations. The excellent thermal insulation properties of carbon aerogels are inseparable from their special nanopore and skeleton structures, therefore, realizing the controllable preparation of the structures of carbon aerogels is the key point to further optimize the thermal insulation properties and to facilitate the practical applications. This paper introduces the relationship between the structure and thermal insulation property of aerogel, summarizes the research progress on the effect of sol-gel preparation process on the structure of carbon aerogel thermal insulation, and provides an appropriate outlook on the research direction of the preparation process.The thermal conductivity of carbon aerogel represents its thermal insulation performance to a certain extent, and can be used as an indicator for the initial screening of carbon aerogel thermal insulation. Generally, the lower the thermal conductivity of the material, the better the thermal insulation performance is expected. Based on heat transfer theory, the thermal conductivity of carbon aerogel is represented as the sum of contributions from solid thermal conductivity, gaseous thermal conductivity, radiative thermal conductivity, and coupling thermal conductivity. Under certain environmental conditions, the thermal conductivity is mainly closely related to the structure (such as particle size, pore size and porosity, etc.) and density of carbon aerogel. Therefore, mastering the correspondence between structure and thermal conductivity, and then guiding the design of the preparation process of carbon aerogel, is the key point to obtain carbon aerogel thermal insulation materials with low thermal conductivity. Therefore, mastering the correspondence between structure and thermal conductivity and then guiding the design of the preparation process of carbon aerogel is the key to obtain low thermal conductivity carbon aerogel thermal insulations. In order to obtain low thermal conductivity, the pore size (at least less than the average free range of gas molecules) and particle size of carbon aerogel should be as small as possible, uniformly distributed, a density of not too large (about 0.10–0.15 g/cm3, and combined with the requirements for the mechanical strength of the material).The structure of carbon aerogel is mainly determined by its preparation process, and the preparation of organic aerogel by sol-gel method is the first step to obtain carbon aerogel. Therefore, the structure of carbon aerogel depends on the structure of organic aerogel,which is affected by the sol-gel reaction and its proceeding conditions, mainly including the concentration of reactants, the type and concentration of catalysts, the parameters of gel-aging and the carbonization process. Among them, the concentration of reactants and the type and concentration of catalysts have the most significant effect on the structure of carbon aerogels. The particle size of the aerogel is mainly affected by and inversely proportional to the concentration of catalyst. The density is mainly affected by and proportional to the concentration of reactants. The pore size distribution and the volume of mesopores are jointly affected by both of them. In order to prepare carbon aerogel thermal insulation with high specific surface area, low density and abundant mesopores, base catalyst is generally selected, at a concentration of not too low. Besides, the specific surface area and the volume of mesopores of carbon aerogels are larger than those of their corresponding organic aerogels at low catalyst concentrations. Additionally, the structural properties of the aerogels can be further improved by introducing surfactants.Summary and prospects Although the potential application of carbon aerogels as high-temperature thermal insulators has been confirmed in some fields, they still face great challenges in the research of many basic problems and practical applications. (1) Establish theory and simulation techniques, to predict the chemical reaction and material migration in the sol-gel process. Develop characterization method including observation of the sol-gel process, such as nucleation, growth and aging. Investigate the influence of process parameters on the nucleation, growth and aging process and analyze the corresponding reaction mechanisms. (2) Enrich the characterization methods for microstructures and develop the three-dimensional reconstruction of microstructure and the prediction of thermal insulation performance, so as to better understand the influence of microstructure on thermal insulation performance. (3) Establish the influence of process parameters on microstructure, so as to realize the controllable preparation of carbon aerogel with low thermal conductivity.

Optical functional hybrid gel glass is a new type of device material with wide potential application. It integrates the characteristics and advantages of gel glasses and optical functional materials, has excellent optical, electrical and chemical properties, and has been widely used in energy, optoelectronics, sensors and other fields. It has become very appropriate device materials in the field of optics and other fields. It is mainly composed of transparent hybrid material glass and optical functional hybrid gel glass, with high refractive index and low scattering, mechanical strength and heat resistance, withstand high temperature and extreme environment, not easy to produce deformation or rupture. Researchers continue to explore and innovate by changing the composition, structure and preparation process of materials. By precisely controlling the microstructure and the distribution of functional substances of the hybrid gel glasses, the performance of optics, electricity and thermology can be effectively regulated.This paper reviews a variety of optical functional hybrid glass devices supported by glass matrices, especially the latest research progress of hybrid gel glass devices supported by gel glass matrices, and mainly systematically introduces two types of glass devices: nonlinear optical laser protection/modulation and luminescence/conversion hybrid glass devices. The most common preparation methods for optical functional hybrid glass devices include in-situ growth, surface coating and direct doping, etc. These methods have their advantages and disadvantages. At present, the combination of glass matrices with a variety of nanomaterials/structures is limited to in-situ growth and surface coating, and it is difficult to achieve high concentration uniform doping of different kinds of functional materials. As far as the glass itself is concerned, inorganic glass has very high physicochemical and thermal stability and excellent optical properties, but the traditional melting method requires high temperature processing, and organic and carbon materials are very easy to oxidize at high temperatures. If we use organic glasses with good compatibility with organic optical materials and no dissolution problems as a matrix, the advantages and disadvantages are very obvious: organic glasses have greater flexibility and impact strength than inorganic glass, and polymerization can be carried out under neutral reaction conditions. However, the lower heat resistance of organic glasses could not be used in high temperatures and extreme environments. The gel glass prepared by the sol-gel method has the characteristics of low temperature preparation, good uniformity and simple process, which makes the high concentration and uniform doping composite possible at room temperature and pressure. This technique has been widely used in the doping of organic functional molecules in inorganic substrates, so that the original optical properties can be maintained or many new optical properties appear.Despite the use of various methods, such as coating, intermolecular physical interaction enhancement (hydrogen bond, ionic bond, π conjugation, electrostatic force, etc.), doping concentration of conjugated organic polymers and functional nanomaterials in transparent substrates, such as gel glasses, is still limited to 1% (mass fraction), usually less than 0.1%. In order to achieve better optical performance, it is necessary to achieve high concentration and uniform doping of various optical functional materials in the transparent matrix. The researchers used silane-functionalized nanomaterials to establish a series of arbitrary concentrations of liquid systems and copolymerized hybrid solid material systems, which can form a variety of solid macroscopic structures: xerogel glasses, monoliths, films, powders, fibers, coatings (glass, plastic, ceramic, metal and other substrates), to achieve the nanomaterials and covalent bond chemical connection, molecular level dispersion and 0–100% arbitrary concentration doping in solid matrix, without any agglomeration and phase separation. This transparent glass is very easy to cut and polish into different shapes and sizes for device design. Through the change of doping concentration and types, it is very convenient to realize the control of optical, mechanics and thermal properties in liquid and solid states, and realize the device and practical application of optical nanomaterials. It is expected to establish a general technical platform for the preparation of nanocomposites and hybrid materials.Summary and prospects Combined with the current research progress, this review looks forward to the problems and challenges that may be faced in the future development of optical functional hybrid gel glasses. The research of optical functional hybrid gel glass devices mainly focuses on exploring and developing new properties and applications of materials. By changing the composition, structure and preparation process of materials, the microstructure and distribution of functional substances of hybrid gel glass can be accurately controlled, and the performance of optical, electricity and heat can be effectively regulated. Despite the breakthrough progress, the research of optical functional hybrid gel glass devices is faced with the problems and challenges in preparation process, performance optimization and market demand. With the increasing demand for new materials and new technologies, by solving these problems, we are expected to promote the development of optical functional hybrid gel glass devices and realize their application and commercialization in various fields, optical functional hybrid gel glass devices will certainly play an important role in the fields of optics, electronics and other fields. This review will hopefully provide some insights into the design and synthesis, performance optimization, as well as device application of optical functional hybrid materials and glass devices, and further promote the development of optical functional hybrid gel glass devices.

Alumina ceramic continuous fiber is one of the most important materials because of its high strength and modulus, high temperature resistance, chemical inertness in both oxidizing and reducing atmospheres even at high temperature, resistance to attack from non-oxide materials, good electrical insulation and low thermal conductivity. The high strength and high-temperature resistance have allowed the development of metal and ceramic matrix composites with high tensile strength or high-temperature load-bearing capability. Thus, alumina ceramic continuous fiber is of great importance in aerospace, advanced manufacturing, and other fields.The Al2O3 content in alumina ceramic fiber is usually more than 70% (mass fraction), and generally contains a small amount of other oxides, such as SiO2, B2O3, Fe2O3, ZrO2, and etc. Amorphous SiO2, transition phase alumina, α-Al2O3 and mullite are the common phases in alumina ceramic fibers, resulting in various phase compositions and microstructures. Chemical composition and the microstructure have great effects on the fibers’ mechanical performance and temperature resistance. Depending on the chemical composition and the microstructure, the alumina ceramic fibers show the tensile strength from 1.5 GPa to 3.1 GPa, and a long-term using temperature varied from 1 000 ℃ to 1 300 ℃. The careful selection is necessary according to the unique circumstances and conditions involved in the use and processing of the alumina fibers. Furthermore, the preparation of alumina ceramic fibers with controlled composition and microstructure is critical.Main methods for manufacturing alumina ceramic fibers can be classified as slurry process, melt-spinning process, prepolymerization process and sol-gel spinning process. The melt spinning method was limited in the length of the fibers, thus, it was not suitable for the preparation of the alumina continuous fibers. While it is difficult to prepare alumina fibers with high strength from the slurry method. Excellent alumina continuous fibers can be obtained through the pre-polymerization process and sol-gel spinning process, in which the sol-gel method shows the advantages of adjustable composition, uniform composition at the atomic level, relative moderate preparation conditions and low cost, becoming the most important preparation method for alumina ceramic continuous fibers.In the past decades, a family of alumina fibers have been developed, typically as the commercial 3M NextelTM alumina ceramic fibers, which have been used in a variety of areas. However, its export to China is restricted by developed countries because of the application in military field, such as aerospace. To develop the local production, many researchers of China have devoted to the preparation of alumina continuous ceramic fibers, mainly by new sol, that is, how to transform from the gel fiber to ceramic fiber. Fortunately, significant progress has been made recently, so that commercialization of the ceramic fiber comes to be true. This further promotes the applications of alumina ceramic fibers. However, there is still a certain gap in performance between the local produced fibers and the fibers abroad. Continued technological innovation is still an important task in the future.Summary and prospects At present, the development of alumina based ceramic continuous fiber in China is mainly carried out under the national academic financial support. The main work at current stage mainly focuses on how to produce the fibers which could meet the basic properties. Most research and development usually rely on model products. Few attention is paid to the research on relevant scientific mechanism and theory, resulting in lack of theoretical support for new applications and in lack of independent innovation ability. Since most of the applications of alumina continuous fiber are based on its performance of high temperature resistance and high strength, it can be predicted that improving the tensile strength and thermal resistance of alumina continuous fiber is still the main goal in the future. Therefore, it is believed as important work to carry out key basic theoretical research, to clarify the intrinsic relationship between the composition-structure-processing-performance of alumina ceramic fibers, and to establish a theoretical model of high-performance alumina ceramic continuous fiber. These investigations can direct the design and preparation of the fibers, to achieve breakthroughs hopefully in the strength and temperature resistance of alumina ceramic continuous fiber, and to furtherly promote the application of fiber and the composite in aerospace and the related fields.