Terahertz (THz) technology has attracted much attention due to its application potentials in high speed wireless communication, non-destructive imaging, spectroscopy and others. However, the development of the materials for THz modulation is still a challenge. Metamaterials composed of periodic subwavelength structures can precisely modulate the amplitude, phase and polarization of electromagnetic waves, providing some opportunities for designing ultra-compact and high-performance THz devices. THz metamaterials modulate THz based on its resonant behavior. However, the modulation efficiency of Mie resonance and other common resonances is not evident due to the low resonant strength. Fano resonance possesses a more intense resonant strength and is sensitive to external dielectric environment, thus greatly improving the efficiency and sensitivity of THz wave modulation. The optically-modulated all-dielectric THz Fano metamaterial with a high efficiency was proposed based on the mechanism of photogenerated non-equilibrium carriers in a high purity silicon. The results show that the optical pump of near infrared laser effectively modulates the Fano resonant strength via controlling the conductivity of high resistance silicon, and the modulation depth reaches 87%, which is 70% greater than that of Mie electric dipole resonance in the same structure, realizing the efficient modulation of terahertz wave. The preparation method is simple and the modulation effect is obvious. The resonant frequency of Fano metamaterial can be conveniently designed by varying the geometric size of the metamaterial, which provides a possible approach for the high-performance modulation devices in the THz regime.

Ceramic materials for microwave systems often show versatile profiles, such as cylindrical and cubic shapes with centimeter sizes. The measurement of such samples thus becomes a challenge. In this paper, a dual-band dielectric sensor based on the complementary split-ring resonators was developed, and a measurement method to characterize the samples with different shapes and sizes was proposed. The resonator creates two operation frequency ranges, which are in wireless communication bands. In each range, numerical simulation was conducted to build the fitting models for each sample. The measurement was conducted to verify the numerical models and the measurement accuracy. The results indicate that the measured accuracy can be as high as 3.5%. Such a measurement method in association with the proposed sensor is competent for dielectric measurement for ceramic of versatile profile, indicating a sample adaptive capability. The novelty of this work lies in its capability of measurement of various samples in a centimeter scale without modifying either the sensor or the material under test (MUT). In addition, a dual-band operation is also a feature of this work, and the discrepancy between the two bands is less than 5%.

To meet the requirements of high-frequency wireless communication, microwave dielectric ceramics of (1-x)MgNb2O6- xCaTiO3 (x=0, 0.02, 0.04, 0.08, 0.12, and 0.16) with a near-zero temperature coefficient were prepared by a solid-state method. The effect of CaTiO3 addition on the microstructure and dielectric properties of MgNb2O6 was investigated, and the formation and sintering behavior of each phase were analyzed. The results show that a proper addition of CaTiO3 can promote the sintering of MgNb2O6 and reduce its sintering temperature. Based on the X-ray diffraction analysis, CaTiO3 can react with MgNb2O6 to form CaNb2O6, Ti8O15, and Ti2Nb10O29 at a high temperature. Increasing the proportion of CaTiO3 reduces the quality factor Q×f, but increases the dielectric constant εr and frequency temperature coefficient τf. When the addition amount (x) of CaTiO3 is 0.16, the sample has the optimum microwave dielectric properties after sintering at 1 250 ℃ for 4 h (i.e., εr=21.6, Q×f =86 601 GHz, and τf = -7.3×10-6/℃).

To meet the requirements of low-latency communication technology in the 6G terahertz band, porous alumina ceramics with ultra-low dielectric constant and directional pore channels were prepared by a freeze-drying method. A relationship between the structure and the properties of samples from different locations was investigated. The effect of solid content on the microstructure, mechanical properties, terahertz optical and dielectric properties was analyzed. Porous alumina ceramics with high porosity (i.e., 68.9%-81.0%) and compressive strength (i.e., 17.6-87.8 MPa) can be obtained, having ultra-low refractive index (i.e., 1.38-1.63), absorption coefficient (i.e., ~2.5 cm-1), dielectric constant (i.e., 1.90-2.67), and z dielectric loss (i.e., ~0.008) at 1 THz. The directional pore channels exhibit high compressive strength in the direction parallel to the pores, and the special structure has potential applications for terahertz waveguides and antenna substrates.

Microwave dielectric ceramics are key materials for manufacturing 5G communication components. The microwave dielectric ceramics of BaSn(Si1-xGex)3O9(0≤x≤1.0) were prepared via conventional solid-state reactions, and the effect of substituting Ge4+ for Si4+ of BaSnSi3O9 ceramic on the sintering behavior, crystal structure, and microwave dielectric properties was investigated. The results show that the BaSnSi3O9 ceramic exhibits the porous microstructure and poor microwave dielectric properties (i.e., εr=6.61, Q×f=7 977 GHz at 15.03 GHz, and τf=-37.8×10-6/℃). The BaSn (Si1-xGex)3O9(0≤x≤1.0) solid solutions are obtained with Ge4+ substitution for Si4+, the crystal structure is a hexagonal structure with P-6c2 space group. The Ge4+ substitution for Si4+ can improve the microwave dielectric properties of BaSn(Si1-xGex)3O9(0≤x≤1.0) ceramics by optimising the sintering behavior and changing the crystal structural parameters. The Q×f values of BaSn(Si1-xGex)3O9(0≤x≤1.0) ceramics are mainly controlled by the relative covalency of Si/Ge-O and Sn-O bonds. As x=1.0, the BaSn(Si1-xGex)3O9 ceramic exhibits the optimal microwave dielectric properties (i.e., εr=8.53, Q×f=15 829 GHz at 14.41 GHz, and τf= -34.2×10-6 ℃-1).

Microwave dielectric ceramics are the key basic materials of 5G/6G communication technology, and the materials with a high quality factor (Q×f), a low dielectric constant (εr) and a near-zero temperature coefficient of resonant frequency (τf) become a focus of research and development. In this paper, a series of garnet Ca3-xMgxYb2Ge3O12 (0≤x≤3) ceramics were prepared by a solid-state reaction approach, and the influence of Mg2+ “rattling” effects in the A-site on the microwave dielectric properties was investigated. The ceramics with 0≤x≤2 exhibit a normal garnet structure, εr gradually increases from 10.3 to 11.8, whereas the Q×f gradually decreases from 98 000 GHz to 78 000 GHz, and τf is in the range from -40×10-6 to -56×10-6/℃. The ceramics with 2<x≤3 have an inverse garnet structure with Mg2+ in the A-site and εr quickly increases to 13.5, whereas the Q×f apparently decreases to 19,800 GHz, and the τf value varies from the negative value to the positive value (+70.5×10-6/℃), which are attributed to the rattling effect Mg2+ and the mismatch between Mg2+ and Yb3+ in the A-site. According to the extrapolated values of the far-infrared reflective spectrum in the microwave region, the intrinsic εr and Q×f values are in a reasonable agreement with the measured values.

To obtain Al2O3-based low-temperature co-fired ceramic (LTCC) materials with low dielectric loss and high breakdown strength, glass/ceramics of x(La2O3-CaO-B2O3-SiO2)(LCBS)+(1-x)Al2O3 were synthesized by a solid-state method. The structure and properties of the sintered samples were characterized by X-ray diffractometer, scanning electron microscope, vector network analyzer, high voltage breakdown instrument, and high-temperature dielectric spectrometer. The results show that adding an appropriate amount of LCBS glass powder can increase the density, reduce the dielectric loss and improve the breakdown strength of the composites. Moreover, based on the complex impedance spectrum analysis, the addition of LCBS can significantly increase the resistivity and activation energy of glass/ceramics. When Al2O3 ceramic with 44 %(mole fraction) LCBS glass (abbreviated G44) is sintered at 850 ℃ for 0.5 h, a LTCC ceramic material with the superior properties (i.e., εr=7.14, Q×f =5 769 GHz at f =13 GHz, and Eb=57.44 kV/mm) can be obtained.

Microwave dielectric ceramics are widely used as dielectric materials in passive devices of the internet of things, industrial internet, 5G communications, and global satellite communication systems. This review introduced the densify mechanism and process parameters of cold sintering process. The main material systems and devices of cold sintered microwave dielectric ceramics were summarized. The main challenges and prospections of cold sintered microwave dielectric ceramics were pointed out. Cold sintering process has some advantages of low sintering temperature (<300 ℃), co-firing heterogeneous materials, small grain size difference before and after sintering, simple preparation process, energy saving and environmental protection, etc., which has potential applications in multi-layer co-fired ceramics and microwave system integration.

Low-dielectric-constant (εr) microwave dielectric ceramics are one of the key materials for future mobile communication technology, and the accurate characterization for their basic performance parameters of εr, Qf value and temperature-dependent coefficient of resonant frequency (τf) is one of the most fundamental issues. Parallel plate method and metal resonant cavity method with TE011 mode are commonly used for measuring the microwave dielectric properties. However, the corresponding problems are neglected, which are especially important for the research and applications of low-εr microwave dielectric ceramics. In this review, the key problems of the identification of TE011 resonant mode, measurement reliability of Qf value and measurement reliability of τf were discussed for the characterization of low-εr microwave dielectric ceramics, and the corresponding solutions to the problems were given.

Microwave dielectric ceramics prepared via a conventional method usually require a high sintering temperature (i.e., >1 000 ℃) and long sintering time, leading to a high energy consumption and a difficulty to realize the integration and co-firing of multiple material system. Continuous innovation and development of wireless communication technology put forward higher requirements for the miniaturization and integration of microwave devices, so that some technologies for preparing low-temperature co-fired ceramic (LTCC) and ultralow-temperature co-fired ceramic (ULTCC) are developed. Developing green sintering technologies with lower sintering temperatures and higher sintering efficiencies becomes one of the research hotspots. Novel sintering technologies (i.e., liquid-phase sintering, hot press sintering, microwave sintering, spark plasma sintering, and flash sintering) promote the development of microwave dielectric ceramics. A novel ultra-low temperature sintering technology called cold sintering process is proposed. The sintering temperature of cold sintering process is rather low (≤300 ℃), which can densify ceramics in a short time, and has some advantages in the phase stability, co-firing of multiple materials and grain boundary manipulation, thus providing an opportunity for the development of ultra-low temperature sintering technology and microwave dielectric material system.

Data-driven methods including machine learning are widely used in materials properties prediction and devices design due to their abilities to discover the underlying statistical correlations from data, achieve target prediction efficiently and accurately, and assist in the analysis of physical images behind the data. In recent years, machine learning modeling in the research of dielectric ceramics and devices becomes popular. Recent development on the research of machine learning prediction models for key properties (i.e., dielectric constant and quality factor of microwave dielectric ceramics) was represented. Machine learning methods in dimensional optimization, failure analysis, etc. for antennas and filters were also introduced. In addition, some prospects of data-driven studies in materials and devices were also provided.

With the development of a high-speed wireless technology, low-temperature co-fired ceramics (LTCC) technology becomes popular. The high-speed, low-delay and high-reliable wireless transmission could be achieved by using LTCC substrates with a low-permittivity (K), a low-loss and a stable-temperature of resonant frequency, as one of functional materials. This review introduced the current situation of commercial substrate materials and alternative LTCCs reported, i.e., ceramic/glass, oxide-assisted sintering, fluoride-assisted sintering and intrinsic low-sintering ceramic systems. The composition, structural characteristics, dielectric properties, coefficient of thermal expansion of low-K LTCCs, as well as the advantages and disadvantages, were also discussed. Some studies of commercial substrates were further described, and their performances in millimeter-wave application were represented. In addition, the development trend of low-K LTCCs was also proposed.

With the development of 5G communication technology and the widespread commercial use of the third-generation wide bandgap semiconductors, the power electronic devices with higher frequency, miniaturization and higher energy efficiency become popular. MnZn ferrite as a high-frequency soft magnetic materials of power electronic devices has attracted attention recently. This review introduced the latest research progress on high frequency MnZn ferrites, including the realization of characteristics of high frequency, wide temperature and low loss through the main component design, additive regulation and low temperature sintering process. This review also represented the stress sensitivity of power loss in the high frequency MnZn ferrite. Somefurther researches on the mechanism of high frequency power loss could accelerate the development and application of low core loss high-frequency MnZn ferrite in this decade.

Microwave composite substrate is one of functional composite materials composing of polymer and inorganic fillers, which is used in microwave band circuits for signal transmission, electrical connections, and supporting components. Microwave composite substrate is a fundamental, common and key material in aerospace, electronic countermeasure, 5G/6G communication and other fields. In the past two decades, the domestic development of microwave composite substrate has made a great progress, but it is still a challenge. This review represented the properties of a microwave composite substrate and elaborated the factors influencing the properties and the functional mechanism. Also, the properties of different microwave composite substrates were discussed according to the category of polymer matrix. The domestic and international research studies on the microwave composite substrates in the past decade was further described. In addition, the development of domestic microwave composite substrate was also prospected to provide some references for improving its manufacture.

Coated catalysts have attracted much attention due to the urgent need of low-resistance technology for large-flow industrial flue gas purification. However, the complex characteristics of coating slurry and the factors influencing the loading for the catalyst preparation become a challenge. For the preparation of Cu-Mn based catalyst by vacuum coating on cordierite substrate, the influence of slurry characteristics (i.e., solid content, binder type, pH value and particle size) on the loading mass and adhesivity of catalyst was investigated. The results show that the increase of solid content makes the catalyst particles more closely bound to the network structure formed by thickener and silica sol, and improves the loading mass and adhesivity of the catalyst. Silica sol can effectively increase the electronegativity on the surfaces of the particles in the slurry, thus leading to the dispersion of the catalyst particles in the slurry. The increase of pH value reduces the zeta potential on the particle surface, reduces the slurry viscosity and improves the slurry stability. Grinding can destroy the uniform and stable network structure of the slurry, affecting the catalyst adhesivity negatively. A coated catalyst with a loading mass of 216 kg·m-3, a shedding rate of 0.6%, and a catalytic CO efficiency of greater than 98% (7 200 h-1, 120 ℃, 8% H2O) is obtained when an unground slurry with a silica sol content of 30% (in mass fraction), pH value of 7.3 and solid content of 30% (in mass fraction) is used.

Developing some thermal insulating composite materials based on perlite is a subject to expand the application of mineral materials. In this paper, the vinyl silicone oil or room-temperature vulcanized silicone rubber was mixed with two kinds of perlite with different sizes and fumed silica as fillers through a kneading process and a direct mixing process, respectively. Some composite silicone rubber insulation boards were prepared and evaluated by the thermal conductivity and insulation performance. The results show that the product prepared by the kneading process has resulted in a reduced heat preservation ability of perlite, probably due to the broken hollow particles. The insulation board prepared with fumed silica as a main filler is difficult to form their shape, and the minimum thermal conductivity is 0.172 8 W·m-1·K-1 for the formed sample. When a mass ratio of perlite and fumed silica in silicone rubber is 37.5% and the product thickness is 2.5 cm, the minimum thermal conductivity is 0.034 9 W·m-1·K-1, and the back-side temperature is 67 ℃ after heating at 250 ℃ for 4 min, which basically meets the application requirements of thermal insulation materials for tobacco facility.

It is important to utilize fly ash (FA) as a resource due to its increasing amount. In this paper, a no-sintered fly ash-based zeolitised ceramsite (FACZ) was prepared by a high-temperature steaming method with FA as a main raw material, silica fume (SF) as a reinforcing agent and additional silicon source to achieve the high-value utilization of fly ash. The pore structure, crystal structure, microscopic morphology and functional group characteristics of the samples at each stage were characterized by specific surface area and pore size analyzer (BET), X-ray diffractometer (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR). The effects of alkali concentration, SF mass fraction, temperature and steaming time on FACZ were investigated. The results show that analcime with a good crystallinity can be synthesized in FACZ under the optimized conditions (i.e., 8 mol/L NaOH, 15% SF and steaming at 190 ℃ for 48 h). The specific surface area of FACZ can reach 14.4 m2/g and the strength is 27.25 MPa after steaming. The removal efficiency of FACZ can reach 99.9%, and the maximum removal amount is 31.934 mg/g under the optimal removal conditions. The removal mechanism is a combined action of silanol and zeolite ion exchange, in which the ion exchange is the main cause.

MoS2 hollow microspheres with a high surface activity and superior piezoelectric properties were prepared by a one-step template-free hydrothermal method with MoO3, KSCN and NaF as raw materials. The effects of hydrothermal reaction temperature, reaction time and NaF addition on the preparation of MoS2 hollow microspheres were investigated. The results show that the samples prepared are 1T phase MoS2 hollow microspheres with the sizes of 0.5-1.0 μm at the hydrothermal temperature of 220 ℃, the hydrothermal time of 16 h, and the amount of NaF added of 12 mmol. According to the results of N2 adsorption-desorption experiments, the specific surface area of MoS2 microspheres is 57.67 m2/g, the pore sizes are mainly distributed between 2-6 nm, and the average pore size is 4.25 nm. The catalytic performance of MoS2 microspheres was evaluated via piezoelectric catalytic degradation of methylene blue solution. Under the action of ultrasound, the degradation rate of MB is 89.3%, and Rhodamine B is 98.9% at 60 s. In the degradation of antibiotics in water, the degradation rate of ciprofloxacin within 120 s is 94.7%.

A novel fabrication method of dense ceria-based barrier layer was proposed to fulfil the low-cost fabrication and long-term operation of solid oxide fuel cell (SOFC). A Y2O3 stabilized ZrO2 (YSZ) electrolyte of anode supported half-cell was immersed in a solution of gadolinium nitrate and cerium nitrate, and treated at 180 ℃ for 36 h, then yielding a dense Gd2O3 doped CeO2 (GDC) thin film. The GDC thin film was co-sintered with screen printed La0.6Sr0.4Co0.2Fe0.8O3-δ cathode at 1 075 ℃, thus obtaining an anode supported single cell. The results show that the hydrothermal grown GDC barrier layer is continuous and dense, with a chemical composition of Gd0.044Ce0.956O2-δ and a thickness of 0.23 μm. The Ohmic resistance of anode supported a single cell at 750 ℃ is 0.101 Ω·cm2, which is 38% lower than that of the cell with a conventional screen printed GDC barrier layer. The maximum power density using a wet hydrogen fuel reaches 1.038 W/cm2 with a decent long-term operation durability. This hydrothermal in-situ growth method can satisfy the low-cost and large-scale fabrication of dense and thin-film barrier layers for SOFC with multi-configurations and dimensions, showing a promising application prospect.

Solid oxide fuel cell (SOFC) is an energy conversion device that converts chemical energy stored in fuel and oxidizer into electrical energy. Since SOFC has some advantages of high efficiency, low product clean pollution and low noise, it thus becomes a hot research topic in recent years. The perovskite type of mixed electron-ion conductor is extensively investigated as a SOFC electrode material. In this paper, PrFe0.7Ni0.3O3-δ (PFN) with an orthorhombic structure was synthesized by a solid-phase method. The results show that the conductivity values are 46.500 and 0.007 S/cm in air and in H2, respectively, when PFN is at 800 ℃. The interfacial polarization impedance values are 0.08 and 0.24 Ω?偸cm2 in air and H2, respectively. The maximum power densities of the PFN/LSGM/PFN symmetric cell are 475 and 180 mW/cm2 at 800 ℃ when using hydrogen or ethanol as a fuel, respectively. It is indicated that Ni-doped PrFeO3 is a promising SOFC electrode material with the superior performance.

The solid oxide electrolytic cell can use a renewable electricity to convert CO2 into CO for storage. However, it still suffers from the sintering of reactive sites and carbon deposition at cathode. In this work, A-site deficient La0.4Ca0.4Ti0.94Ni0.06O3-δ perovskite cathode with the decoration of a large number of exsolved Ni nanoparticles was prepared by an in-situ exsolution method. Also, a promoter of CeO2 was introduced into the system via different synthetic methods (i.e., doping, impregnation and mechanical mixing) to construct a “cerium oxide-metal-perovskite” three-phase composite cathode material. The results show that the carbon deposition resistance and electrochemical performance of the mechanical mixed modified materials can be improved at 800℃, 70% (in volume) CO2/30%CO and 1.4 V electrolytic voltage. The current density is increased by 3 times and the voltage decay rate is decreased by 58%. Such an improvement is correlated to the increased amount of surface oxygen vacancies and the strengthened CO2 absorption.

In order to improve the serious polarization problem of zinc negative electrode in zinc-nickel secondary batteries and to improve the electrochemical performance and cycling stability of zinc negative electrode, a hydrothermal-coprecipitation method was used to prepare CaSn(OH)6 deposited on the surface of calcium zincate and used as a negative active substance of zinc-nickel batteries. The results show that the hydrothermal-coprecipitation method can be used to deposit CaSn(OH)6 on the surface of calcium zincate, and the prepared calcium zincate has a high crystallinity. Based on the cyclic voltammetry test, the addition of CaSn(OH)6 reduces the charge transfer resistance of calcium zincate and is beneficial to accelerating the electrochemical reaction rate of calcium zincate in alkaline electrolyte, thus improving the discharge rate in the reaction process. The results of electrochemical impedance spectroscopy confirm that calcium zincate with CaSn(OH)6 deposited on the surface electrode charge transfers impedance less rather than that of pure calcium zincate. The capacity retention rate of the battery is 85.34% after 70 charge discharge cycles at 0.2 C when calcium zincate with CaSn(OH)6 deposited on the surface is used as a negative active material of Zn-Ni battery.

The development of a high-property ammonia gas sensor is of great significance for human health and environmental protection. Herein, MgFe2O4 nanomaterial was synthesized by a sol-gel method, and then a series of Ti3C2Tx-MgFe2O4 composites were prepared by an ethanol ultrasonic dispersion method. The structure and morphology of Ti3C2Tx-MgFe2O4 composites were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The gas sensing performance of the sensors based on different ratios of Ti3C2Tx-MgFe2O4 composites was investigated. The result shows that the gas response of 2.5% (in mass) Ti3C2Tx-MgFe2O4 composite (Ra/Rg=4.7) to 100 μL/L ammonia at 25 ℃ is 3.6 times greater than that of pristine MgFe2O4 nanomaterial (Ra/Rg=1.3). Meanwhile, this composite exhibits superior selectivity and fast response/recovery durations (i.e., 10.8 s/6.6 s).

A novel phosphate binder was prepared with homemade aluminum dihydrogen phosphate as a matrix and nano-Al2O3, Si powder and low-temperature fused glass powder (Zn-B-Si-Al-R) as fillers to enhance the high-temperature resistance of phosphate adhesives. The interface reaction mechanism was analyzed. The results show that the high-temperature tensile strength of the adhesive is 5.28 MPa at 500 ℃, and the mass loss is only 7.8% when the additions of Fe2O3, ZrO2 and CuO are 5% (in mass), 10% and 15%, respectively. From room temperature to 500 ℃, the coefficient of thermal expansion of the adhesive matches well with the stainless steel substrate, and the difference is less than 1.5×10-6 K-1. Meanwhile, the discrepancy of electric potentials promotes the ions exchange of Fe and Cu, forming the composition gradient layer at the interface, which effectively relieves the thermal stress caused by thermal mismatch and improves the bond strength of the adhesive at a high temperature.

The control of pollutants has attracted considerable recent attention. The removal technology of antibiotics as pollutants becomes a challenge, especially water treatment technology based on photocatalytic degradation of antibiotics. In this paper, WO3 was prepared by a hydrothermal method, and the S-scheme heterojunction BiOBr/WO3 was constructed by a precipitation method at room temperature. Compared with BiOBr and WO3, the formation of S-scheme heterojunction improves the photocatalytic activity, and reduces the recombination rate of photogenerated electron-hole pairs. The optimum photocatalytic performance of BiOBr/WO3 with a mass fraction of 20% can be achieved, and the degradation rate for ciprofloxacin (CIP) is 94.93% within 120 min. Based on the electron spin resonance and radical trapping experiments, ·O2- is a primary active component in the photocatalytic degradation of CIP. The results of high-performance liquid chromatography-mass spectrometer system indicate that six intermediates are produced during the degradation of CIP, which are eventually mineralized into CO2, H2O and other inorganic ions.

This paper was to construct ensemble feature selection and random forest for the identification of ancient glass products via integrating the machine learning algorithm into the identification and analysis of ancient glass products and taking accuracy rate and AUC as the measurement indexes of classification performance. The results of different feature selection methods were analyzed, and the important chemical components were selected. The selected important features with random forest, k-nearest neighbor learning and naive Bayesian were investigated. The results show that lead oxide, barium oxide, and potassium oxide have an impact on the weathering of the glass surface by using ensemble feature selection. In high potassium glass, three components are closely related, the accuracy of classification by the random forest based on the k-fold cross validation for selected important features is great, and the model is stable. This method can provide a theoretical reference for the composition analysis and category identification of ancient glass products, and other glasses.

Solid oxide fuel cell (SOFC) is a high-efficiency, fuel-flexible, all-solid-state fuel cell, which is the focus of competing research and development around the world. It operates at a high temperature for a long time, and the material properties of the running components are quite different. The problems of component damage and failure caused by the inevitable internal thermal stress severely affect its commercial application. The thermal failure of SOFC has different manifestations and mechanisms in different scales. This review summarized recent work on the stack, single cell and electrode. The corresponding comments and suggestions in this field were given. This review could provide a guidance for studies on the thermal failure problems of SOFCs.

Amorphous carbon materials exhibit more advantages in mechanical, optical and thermal properties with the increasing concentration of sp3-hybridized bonds. High pressure, as an extreme physical condition, can effectively trigger sp2 to sp3 bonding conversion in carbon materials. In this review, some recent achievements and progress on the synthesis of new superhard amorphous carbon materials under high pressure were introduced, mainly including the studies on the transformation of fullerene and glassy carbon into sp3 amorphous carbon material under high pressure and high temperature or high pressure with shear stress. These results deepen our understanding on the structural transition of covalently bonded amorphous materials and the relation between their microstructure and properties. Based on this, we also hold out some prospect for the future study of new superhard sp3 amorphous carbon materials under extreme conditions.