Transparent ceramic is a kind of inorganic nonmetallic material with broad application prospects. However, the traditional preparation strategy based on powder sintering has technical limitations of relying on high-quality raw material powder, requiring long time high temperature treatment, complex equipment and process, and high production cost. Glass crystallization is a new method to achieve full crystallization of glass and obtain transparent ceramics by controlling the crystallization process. This method can overcome the technical difficulties associated with the traditional transparent ceramic processing. Meanwhile, it also shows unique advantages in preparing high density, pore-free, non-cubic phase, nanostructured transparent ceramics and has attracted significant attention. In this paper, the development and research status of glass crystallization method were reviewed in detail from two aspects: fully glass-crystallization of oxide transparent ceramics and related component systems. Then, the problems existing in the current research were pointed out, and the future development prospects were prospected. It is expected that this method can be widely used to prepare the next generation of high performance transparent ceramic materials.

In this paper, the influence of miscut-angle on the processing of β-Ga2O3 (100) plane substrates was studied. The morphology changes of (100) plane substrates during the processing were analyzed when the miscut-angles were 0°, 1° and 6°, respectively. Furthermore, the influence of different parameters on the polishing of the substrate was analyzed. The experimental results show that with the increase of the miscut-angle, the cleavage damage of (100) plane substrate reduces, the surface roughness reduces after machining, and the way of material removal transformed from brittle removal to brittle plastic mixed removal to plastic removal. Low polishing pressure can effectively suppress the cleavage damage and improve the surface quality. When the miscut-angle is 6°, the polishing efficiency of (100) plane substrate is high, and the surface roughness after polishing can reach Ra≤0.2 nm.

The relaxor-based ferroelectric single crystals grown by vertical Bridgman method are cylindrical ingots with no natural crystallization face. The crystallographic orientations are required before cutting and processing. In this work, we proposed a simple method for determining crystallographic orientations of ferroelectric single crystal using powder X-ray diffractometer and X-ray orientation instrument. Firstly, the Miller indices of the strongest diffraction peak of arbitrarily cut plane are determined by a powder X-ray diffractometer. Secondly, the cut plane of crystal ingots is determined according to the Miller indices of the strongest diffraction peak by an X-ray orientation instrument. Thirdly, the intersection direction of the two crystallographic planes is obtained by X-ray orientation instrument. The three-dimensional orientations of ferroelectric single crystal are obtained based on the intersection direction and the crystallographic planes of the strongest diffraction peak. The application of this method to Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals demonstrates that it is a high accurate, high efficient, convenient, and waste-free method for crystallographic orientation. In addition, this method is also suitable for other crystals.

Halide scintillation crystals with neutron-gamma dual detection capabilities show broad application prospects in the field of radiation detection. High optical quality NaI∶Tl and NaI∶Tl,Li scintillation crystals were grown by Bridgman method in this paper. The photoluminescence excitation (PLE) and emission (PL), time-resolved photoluminescence, X-ray excited radioluminescence (XEL), γ-ray detection performance and neutron-gamma discrimination performance of NaI∶Tl co-doped with different Li concentrations were systematically studied. Under the excitation of X-ray, NaI∶Tl and NaI∶Tl,Li crystals show emission peaking at 345 and 410 nm respectively, which are related to sp-s2 transitions of Tl+ ion. As the increase of Li co-doping concentration, the light yield of the crystal decreases from 41 000 photons/MeV to 23 000 photons/MeV, while the energy resolution at 662 keV deteriorates from 7.0% to 9.6%. Among the tested samples, the NaI∶Tl crystal co-doped with 1% Li has the best neutron-gamma pulse shape discrimination (PSD) performance, and the neutron-gamma PSD figure-of-merits (FoM) reaches 4.56.

Cadmium zinc telluride (Cd1-xZnxTe, referred to as CdZnTe or CZT) is a room-temperature nuclear radiation detection material, which is promising for use in the fields of medical imaging, environmental monitor and space exploration, due to its superior photoelectric properties. Traveling heater method (THM) is considered to be one of the most promising methods for growing CZT single crystals. During the crystal growth, a suitable temperature field is a prerequisite for obtaining high-quality crystals. In this paper, the Fluent software is used to study the thermal field of a resistance-heated THM growth system. A physical and mathematical model describing the thermal transport of the system is established, and an inverse simulation method for establishing temperature control points is proposed to solve the problems of the heaters’ power. The calculated values of the power of five heaters in the furnace are 225.6, 343.7, 1 045.9, 92.5 and 199.6 W respectively, which are in good agreement with the experimental measurements. Furthermore, the effects of furnace structures such as the distance between the heater and the heating tube, and the width of the heat-dissipation zone on the temperature distribution in the CZT zone in the crucible were studied. The research results show that the maximum temperature decreases by 3.7% and 5.6% when the distance between the heater and the heating tube increases from 5 mm to 10 and 15 mm, and the width of the melting zone decreases by 32.7% and 50.0% when the width of the heat-dissipation zone increases from 30 mm to 50 and 80 mm.

Porous GaN thin films were successfully prepared by high-temperature annealing of GaN thin films with Au nanoparticles deposited on their surfaces in H2 and N2 atmosphere. The surface morphology of the porous structure can be regulated by parameters such as annealing temperature, annealing time and Au deposition time. The crystal quality of different GaN structures was characterized by high-resolution X-ray diffraction (HRXRD) and Raman spectroscopy. Compared with planar GaN, the dislocation density and residual stress of porous GaN are reduced. When the annealing temperature is 1 000 ℃, the dislocation density is the lowest and more compressive stress is released. The optical properties of the porous GaN were characterized by photoluminescence (PL) spectroscopy. Compared with planar GaN, the luminous intensity of porous GaN is significantly improved, which can be attributed to the increased porosity of the porous structure, and therefore effectively increased light scattering. In addition, the photocurrent density of different GaN structures was tested by electrochemical work station, and the results confirm that the photocurrent density of porous GaN with larger specific surface area can be increased by about 1.67 times when used as a working electrode. Porous GaN thin films through high-temperature etching are successfully prepared in this paper, which providing some theoretical guidance for the improvement of the crystal quality and optical properties of the GaN epitaxial layer, and also shed some light on its application in the fields of photoelectric catalysis.

The electrode made of transparent semiconductor indium tin oxide (ITO) can reduce the edge current crowding effect of photoconductive semiconductor switches and improve the utilization of pulse laser. In this paper, 10 nm Ti and TiN layer were inserted into the interface between ITO and GaN, and the influences of Ti and TiN layer on the Ohmic contact performance between ITO and GaN were studied. I-V test results show that with the increase of the annealing temperature, the GaN photoconductive semiconductor switch with Ti insertion layer changes from Ohmic contact to Schottky contact, while the photoconductive semiconductor switch with TiN insertion layer keeps Ohmic contact characteristics. TEM observation shows that when Ti is used as the insertion layer, ITO diffuses through the insertion layer to the interface between the insertion layer and GaN, resulting in the formation of Ti oxide and holes at the interface. The transmission spectra show that the transmittance of samples with Ti insertion layer is less than 38.3% at different annealing temperatures, while the transmittance is 38.8%~55.0% when TiN is used as the insertion layer. Therefore, the photoconductive semiconductor switch containing TiN insertion layer shows a higher thermal stability and transmittance, which provides reference for the application of GaN photoconductive semiconductor switch in the field of high temperature and high power.

In this paper, a series of ITO thin films with different concentrations of metal Sn doping were prepared by electron beam evaporation technique. X-ray diffractometer, atomic force microscope, UV-Vis-NIR spectrophotometer, four-probe resistivity meter and Z-scan system were used to measure and characterize the physical phase structure, microscopic morphology, optical absorption, square resistance and nonlinear optical properties of ITO films, respectively. The test results show that, with the increase of metal Sn doping concentration from 10% to 30%: the crystalline quality of the ITO film is enhanced; the surface roughness of the film increases and the grain size gradually increases; the plasma absorption is enhanced and the position of the absorption peak is red-shifted and the optical band gap is narrowed; the square resistance of the film continuously reduces; the nonlinear absorption coefficient gradually increases, and the maximum absolute value can be increased to 2.59× 10-7 cm/W. The finite-difference fitting results in the time domain show that the variation pattern of electric field intensity of ITO thin film samples with different metal Sn doping concentrations is consistent with the experimental results.

In this paper, an active region structure of GaAs-based 1 060 nm high performance laser diode was designed. An strain compensation structure of antimonide GaAsP/InGaAs/GaAsSb/InGaAsSb/GaAsP was introduced into the active region, which alter the energy band structure of active region and solve the limitation of bandgap width on emission wavelength. The weak type Ⅱ quantum well band structure is transformed into type Ⅰ, and the overlap of the electron and hole wave functions increase. The transition probability, radiation recombination probability and internal quantum efficiency are improved, and the non-radiative recombination is reduced. Therefore, output power and electro-optical conversion efficiency of the device are effectively enhanced. Additionally, an asymmetric hetero-double narrow waveguide structure was designed. The p-side of the structure used AlGaAs with large conduction band offset and small valence band offset as the inner and outer waveguide layers, which is beneficial for valence band holes injecting into the active region and restricted electrons in the conduction band. The n-side of the structure used GaInAsP with small conduction band offset and large valence band offset as the inner and outer waveguide layers, which is beneficial for conduction band electrons injecting into the active region and forming a higher potential barrier for holes in the valence band. The electrons injection barrier and holes injection barrier are reduced from 218 and 172 meV to 148 and 155 meV, respectively, which improve the carrier injection efficiency. The electron leakage barrier and hole leakage barrier are increased from 252 and 287 meV to 289 and 310 meV, respectively, which enhance carrier confined ability. Finally, output power and electro-optical conversion efficiency of laser diode reach 6.27 W and 85.39%, respectively. The results provide theoretical guidance and data support for achieving high-performance GaAs-based 1 060 nm laser diode.

MnBi2Te4 is an intrinsic magnetic topological insulator discovered for the first time, which has important research significance. In this paper, Er-doped MnBi2Te4 crystal were synthesized by doping rare earth elements in MnBi2Te4 crystal. The Er atom enters the lattice and replaces the Mn site. Considering the long period of crystal preparation process and the existence of impurities such as Bi2Te3 flux in the product during crystal preparation, the crystal preparation process was optimized. XRD analysis shows that the Er-doped MnBi2Te4 crystal prepared by the optimized process has good crystallinity and no impurity phase. The magnetoelectric transport measurement results show that a small amount of Er-doped MnBi2Te4 crystal has enhanced magnetic properties, and the doped samples undergo antiferromagnetic phase transition at 25.2 K. The layer spacing of Er-doped MnBi2Te4 crystal was studied by atomic force microscopy. The layer spacing is an integral multiple of that of single-layer MnBi2Te4. The phonon vibration mode of Er-doped MnBi2Te4 crystal was studied by Raman measurement, and the results show that doping Er is a feasible method to adjust the magnetic properties of MnBi2Te4.

In this study, the influence mechanism of crucible rotation rates on the flow field and oxygen concentration of 200 mm semiconductor-grade Czochralski monocrystalline silicon under transverse magnetic field was investigated using ANSYS finite element software. The results show that flow field and oxygen concentration distribution of the silicon melt exhibit three-dimensional asymmetry under transverse magnetic field. The convective forms of the melt mainly include Taylor-Proundman vertices, buoyance-thermocapillary vortices, and secondary vortices. The former two contributed to the volatilization of oxygen, while the latter one had a suppressing effect. When the crucible rotation rate is low (0.5~1.0 r/min), the weaker convective strength of the melt results in low thermal conductivity efficiency between the crucible wall and the solid-liquid interface, and oxygen mainly migrates to the solid-liquid interface through a diffusion mechanism, resulting in high oxygen concentration in silicon melt. When the crucible rotation rate is high (2~2.5 r/min), oxygen migrates to the solid-liquid interface through strong convective forms. As the crucible rotation rate increases, the strength of the secondary vortices and buoyancy-thermocapillary vortices increases, and the region affected by the latter moved away from the free surface, resulting in a trend of first decreasing and then increasing oxygen concentration in the silicon melt. Both the numerical simulation results and experimental results indicate that a crucible rotation rate of 1.5 r/min is optimal for obtaining monocrystalline silicon with lower average oxygen concentration. The results of comparative analysis between experiments and numerical simulations can provide a reference basis for optimizing the parameters of the crystal growth process under transverse magnetic field.

In order to investigate the ultra precision cutting characteristics of monocrystalline silicon, nanoindentation and nanoscratch experiments were conducted on surface of monocrystalline silicon using a nanoindentation instrument and a Berkovich diamond indenter. In the nanoindentation experiment, the indenter was pressed onto the surface of monocrystalline silicon under 10, 30, and 50 mN loads, respectively. It is found that there are slight fluctuations in the load displacement curve under 30 mN load, while a "pop out" phenomenon occurred under 50 mN load, indicating a sudden stress change and brittle failure of the material, the critical load for brittle-plastic transition of monocrystalline silicon was predicted to be slightly less than 30 mN. Nanoscratch experiments with variable loads from 0 to 100 mN were carried out. According to the load-displacement curve, it is observed that monocrystalline silicon scratching can be divided into elastic-plastic removal and brittle removal stages during variable load. In the elastic-plastic removal stage, the load-displacement curve fluctuates smoothly, while in the brittle removal stage, the curve fluctuates significantly. The critical load for the brittle-plastic transition of monocrystalline silicon is 27 mN, and the critical depth is 392 nm. Finally, through the constant load nanoscratch experiment, the surface of monocrystalline silicon was scratched at a constant load of 5, 10, and 20 mN in the plastic processing region, respectively. The surface morphology of monocrystalline silicon after constant load scratch was observed by scanning electron microscopy (SEM). The scratching analysis data shows that the cutting force and elastic recovery rate increases with the increase of load, while the friction coefficient first increases and then decreases. Therefore, in ultra precision machining of monocrystalline silicon, it is necessary to select a reasonable machining load and fully consider the impact of elastic recovery.

Al-Si alloy purification method is an up-and-coming method for the preparation of solar-grade polysilicon raw materials because of its low production cost, high removal efficiency and single by-product. In this process, Al as a solvent will inevitably contaminate Si, and how to reduce the content of Al in primary silicon is one of the urgent problems to be solved. In this paper, a small amount of Cu was added to Al-50%Si alloy, the effect of Cu on the thermomechanical properties of the alloy solution was analyzed, and the inhibitory effect of Cu on Al contamination in combination with the existing form of Cu was explored. The results show that the activity coefficient of Al in the alloy reduces to 0.714 8 with 10% (mass fraction) Cu addition. The content of Al in the primary silicon reduces from 250.960 mg/kg to 181.637 mg/kg, which is 27.62% less than that without the addition of Cu. Meanwhile, the residual Cu in primary silicon is only 12.6 mg/kg, which is lower than the solid solution of Cu in Si. The introduction of Cu into the Al-Si alloy does not cause secondary contamination of the primary silicon. Therefore, using Al-Si-Cu ternary alloy system for purification to prepare solar-grade polysilicon can effectively suppress Al contamination of primary silicon.

The photoelectric properties of four two-dimensional bilayer MoSSe/WSSe van der Waals (vdW) heterostructures were investigated by the first-principles calculations. All four heterostructures have been conformed thermodynamic stable by the phonon spectra. Bilayer MoSSe/WSSe heterostructures can be indirect or direct semiconductor, depending on the stacking routes. Moreover, two Janus MoSSe/WSSe heterostructures show the suitable band gap of 1.22 and 1.88 eV, notable absorption index on the visible light, and band edge positions straddling the water redox potential. Therefore, Janus MoSSe/WSSe heterostructures are expected to have application prospects in the field of photocatalytic water decomposition.

The crystal structure, charge density distribution, band structure, density of states (DOS), and optical properties of Al-doped β-Ga2O3 (i.e. (AlxGa1-x)2O3) with different Al concentrations were calculated by the first-principles based on density functional theory. The calculated results for intrinsic and Al-doped β-Ga2O3 with various Al concentrations were compared. The results show that, as the Al concentration increases, both the lattice parameters and bond lengths of (AlxGa1-x)2O3 monotonously decrease, whereas the band gap progressively widens. It is found that an intermediate band exists above the conduction band minimum (CBM), which is mainly composed of Ga 4s and Al 3p orbitals. Al doping enlarges the band gap by introducing impurity energy levels in this intermediate conduction band. Meanwhile, the introduction of Al atoms shifts the density of states to high-energy side by nearly 3 eV, which also leads to an increase of the band gap. According to the optical property calculation results, a significant blue shift for both the imaginary part of the dielectric function and the absorption coefficient are observed after Al doping. This blue shift behavior is generated by the transition from the O 2p states in the valence band maximum (VBM) to the Ga 4s states in the CBM. Moreover, the blue shift is intensified with the increase of Al doping concentration. This investigation can provide ideas and theoretical guidance for the construction of optoelectronic devices based on (AlxGa1-x)2O3.

In this paper, a series of Cs3Cu2I5 perovskite phosphors modified with L-histidine (L-His) and 5-aminovaleric (5-Ava) acid were prepared by simple room temperature ball milling method. The phase, morphology, optical and stability properties of Cs3Cu2I5∶x%L-His and Cs3Cu2I5∶x%5-Ava(x=0, 0.5, 1, 1.5, 2) perovskites were analyzed. The presence of amino acids does not change the crystal structure of Cs3Cu2I5perovskite, which still belongs to the Pnma space group. However, the introduction of amino acids affects the grain size of perovskite and effectively improves its optoelectronic properties. When x=1, the fluorescence intensity of Cs3Cu2I5 perovskite modified with L-His and 5-Ava increases by about 1.30 and 1.41 times compared with that of pure Cs3Cu2I5 perovskite, and the photoluminescence quantum yield (PLQY) increases by 25.09 percentage points and 30.47 percentage points, respectively. The fluorescence lifetime of the modified perovskites is effectively prolonged. It is found that the improvement in performance may be related to the function of amino and carboxyl groups in amino acids, which blunts the defects of perovskites and inhibits energy loss in non-radiative recombination processes. In addition, the blue light-emitting diode (LED) was prepared by Cs3Cu2I5 perovskite phosphor modified with L-His and 5-Ava acid, and the respective light efficiency is 1.85 and 2.10 times higher than that of pure Cs3Cu2I5 device under biased current of 70 mA, indicating that such materials have great application value in the LED field.

Electrocatalytic hydrogen production, to produce hydrogen (H2) and oxygen (O2) at the same time through hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which is considered as an efficient and environmentally friendly way to produce hydrogen. However, the high-efficiency catalysts for commercialization are expensive and have limited reserves, which limit the large-scale application of electrolytic water technology. Therefore, the development of efficient electrocatalysts with low cost, high stability and environmental friendliness, especially phosphides based on non-precious metal materials, is very challenging and much desired. Here, Mo-doped Ni5P4 catalysts with hollow nanoflower structure were successfully prepared by hydrothermal and relatively low phosphorylation temperature. The microstructure of Mo-Ni5P4 catalysts was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the electrochemical properties of Mo-Ni5P4 materials were investigated. The results show that, catalysts synthesized in this work promote the rate of the HER water dissociation step, taking advantage of the Mo and Ni5P4 hollow structures change and the large surface area of the porous nanosheets. In alkaline electrolytes, Ni5P4 under Mo loading requires only 116 mV of hydrogen evolution overpotential to achieve a current density of 10 mA·cm-2, while only 255 mV of oxygen evolution overpotential is required. In a two-electrode configuration, a battery voltage of only 1.608 V is required. The catalyst still shows good stability after 27 h of continuous testing.

The development of high catalytic activity and cheap catalyst is the key of catalytic decomposition of water to produce hydrogen. The transition metal nickel nitride (Ni3N) has excellent thermal/chemical stability, electrochemical activity and noble metal-like properties, which attracts more and more researchers’ interest. However, in the process of Ni3N alkaline electrocatalysis of hydrogen evolution reaction, the dissociation efficiency of water is low, and the adsorption of the intermediate proton is too strong, which result in the much lower performance of Ni3N than Pt catalyst. In this work, Ru-doped porous Ni3N nanosheets (Ni3N/Ru) were prepared successfully by two-step method of hydrothermal and nitriding process. The composition, morphology and structure of Ni3N/Ru materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic mechanism was analyzed by X-ray photoelectron diffractometer (XPS), and the effect of Ru doping amount on the morphology and electrocatalytic performance of Ni3N materials was also studied. The results show that Ni3N loaded with 6.30%Ru needs only an overpotential of 49 mV to drive the current density of 10 mA·m-2 in 1 mol/L KOH electrolyte, which is comparable to commercial Pt/C (46 mV@10 mA·cm-2). The Ni3N/Ru were then assembled into a two-electrode system for overall water splitting, and the cell voltage required to reach the current density of 10 mA·cm-2 is only 1.54 V. The outstanding catalytic performance is attributed to the fact that Ru doping Ni3N effectively improves the dissociation of water, reduces the electron cloud density of Ni and N in Ni3N, promotes the formation process of adsorbed hydrogen intermediates (H++e-=H*), improves hydrogen evolution reaction kinetics, and thus enhances its electrocatalytic performance.

In this paper, a cobalt-doped carbon-based compound was prepared from anhydrous glucose and cobalt nitrate hexahydrate by a combination of hydrothermal method and in situ loading, and applied as an activator of potassium monopersulfate (PMS) for catalytic degradation of tetracycline in water. The prepared cobalt-doped carbon-based compounds were characterized by XRD, SEM, TEM, XPS, etc. The reason why the degradation effect of tetracycline by this catalyst was significantly higher than that of a single hydrothermal carbon was analyzed from the aspects of crystal structure, microstructure, and surface chemical elements. In addition, the effects of catalyst dosage, PMS dosage, and solution pH on the catalytic degradation of tetracycline were investigated. The experimental results show that, under the optimal reaction conditions, the cobalt-doped carbon-based compounds catalyze the degradation of tetracycline for 60 min, the degradation rate of tetracycline reaches 95.84% (k=0.051 36 min-1). The degradation mechanism was also investigated, and the analysis results show that Co0 and Co2+ in the cobalt-doped carbon-based material are involved in the activation of potassium monopersulfate to produce ·O-2, SO·-4, 1O2,·OH, and thus the materials have the ability to catalyze the degradation of tetracycline with high efficiency, which is promising for the treatment of antibiotic wastewater.

The calcium sulfate dihydrate whiskers (CSW) were prepared using rare earth gypsum as raw material, and the effects of preparation methods on the morphology and structure of CSW were studied. The effect of rare earth cerium on the structure and morphology of CSW was investigated using pure calcium sulfate dihydrate as raw material and CeCl3·7H2O as cerium source. The structure, morphology, composition, and fluorescence properties of CSW were characterized and analyzed by SEM, XRD, XPS and FL. The results show that calcium sulfate dihydrate whiskers with high aspect ratio can be prepared by microwave method, with average length of 263 μm and average aspect ratio of 39.50. Ce3+ enters CSW in the form of atomic substitution during the formation of CSW, which does not affect the crystal structure of CSW, but improves the morphology of CSW. When 2% (mass fraction) Ce3+ is added, one-dimensional growth of CSW is promoted to make the aspect ratio of CSW increase significantly, while excessive Ce3+ leads to the growth of whiskers in the transverse direction. This study proves that rare earth gypsum contains trace amounts of rare earth element Ce. At the same time, it is found that CSW prepared from rare earth gypsum presents the characteristics of emitting blue light, which provides theoretical guidance for the development and utilization of rare earth gypsum.

Sapphire single crystal is the currently preferred material for transparent armor for its excellent mechanical properties and optical properties. Edge-defined film-fed growth (EFG) method can be used to grow crystal with shape and size close to the target requirements, and reduce the production cost greatly. In this paper, the equipment for growing super large sapphire crystal with EFG mothed was designed, the thermal field and conditions were optimized, and a sapphire single crystal plate with size of 480 mm×1 200 mm×12 mm was grown successfully. Its shape is regular, and no scattering is found under irradiation of 20 mW He-Ne laser after removing the surface bubble layer.