BaTiO₃-Bi(Mg_0.5Zr_0.25Ti_0.25)O₃ ceramic was prepared by a solid-state method, and the influence of Bi(Mg_0.5Zr_0.25Ti_0.25)O₃ content on the microstructure, dielectric, ferroelectric and energy storage properties of BaTiO₃-based ceramics was investigated. The ceramic has a tetragonal phase structure when the sample composition x≤0.03, and the structure of the ceramic changes from a tetragonal phase to a cubic phase when x≥0.06. This ceramic shows a good temperature stability. The dielectric constant peak becomes wider and lower, and the material gradually changes from a ferroelectric to a relaxor ferroelectric as Bi(Mg_0.5Zr_0.25Ti_0.25)O₃ content in the composition increases. The dielectric constant of the sample keeps stable from room temperature to 500 ℃. The addition of Bi(Mg_0.5Zr_0.25Ti_0.25)O₃ can make the hysteresis loop to be slimer, the remnant polarization P_r decreases, and the integral area of the upper branch of P-E loop with respect to the polarization axis become larger. Thus, the material energy storage density increases. The energy storage density of the material firstly increases and then decreases, while the energy storage efficiency increases from 75.08% to 92.35%. The maximum energy density of 0.80 J/cm³ can be obtained with a high efficiency of 88.97% as x=0.1.

A demand for large size and high-performance potassium dideuterium phosphate crystals (DKDP) is increasing with the development of high-power laser system. Compared with the conventional methods, a rapid growth method can shorten the crystal growth period and improve the crystal growth efficiency. However, the properties of the rapidly growing DKDP crystals in pyramidal and prismatic regions are different, leading to the inhomogeneity of the properties in different positions and restricts its application in high-power laser systems. In this paper, potassium dideuterium phosphate crystals with a medium size were grown by a point seed rapid growth method. The feasibility of using rapidly-growth DKDP crystal as electro-optical switch and frequency converter was analyzed by transmittance spectroscopy according to the linear absorption properties. The homogeneity of deuterium content and the crystal quality were analyzed by Raman spectroscopy and rocking curve analysis, respectively. This work can provide a reference for the growth and application of large size potassium dideuterium phosphate crystal.

β-Ga₂O₃ is one of the most promising ultrawide band-gap semiconductor materials, but its crystal defects are not investigated comprehensively. The low angle grain boundaries of β-Ga₂O₃ crystal mainly exists in (100) plane. The existence of low angle boundary can destroy the integrity of the crystal structure and reduce the quality of crystal. The macroscopic analysis and microstructure characterization of the low angle grain boundaries in the β-Ga₂O₃ crystal grown by edge-defined film-fed growth method were carried out by chemical etching analysis and transmission electron microscopy. The results show that the shape and orientation of the etch pits on both sides of the low angle grain boundary are consistent, and the misorientation angle of the low angle grain boundary is 3°. In addition, the low angle grain boundary can cause the double peaks and broadening in the X-ray rocking curve. The gap in the study of low angle grain boundary is filled based on the characterization of the microstructure of low angle grain boundary in β-Ga₂O₃ crystals.

The application of CaF₂ crystal in photolithographic machine becomes a hot research topic. However, differentdefects in the crystal seriously restrict its actual performance. In this paper, the morphological and spatial extension characteristics of etch pits formed by the crystal face (111) of CaF₂ crystal were observed, and the corresponding defect characteristics of various etch pits were analyzed, which is aprerequisite for the accurate characterization and control of crystal defects. The results show that the etch pits on the crystal face (111) of CaF₂ have three types, i.e., triangular conical pit, cone-flat bottom pit and flat bottom pit. Triangular conical pits and cone-flat bottom pits have directional movement characteristics, indicating that the corresponding defects of these pits are related to the dislocations of the materials. However, there is no spatial extension in the flat bottom pit, which is formed after the defects are completely corroded, and the corresponding defects may be the remains of local defects such as impurities, vacancies and small dislocation rings. The physical parameters of the formation process of the etch pit are obtained, and the kinematic model of the etch pit is establishedby tracking the evolution process of the etch pit in real time. This work provides a basis for further studiesonthe corrosion theory of crystal materials.

The optimization of dielectric properties for high dielectric perovskite-like ceramics is a research hotspot. (NaLn)Cu₃Ti₄O₁₂ (Ln=Ce; Nd) dielectric ceramicswere prepared by ahigh-temperature solid-state methodat different sintering temperatures. The phase characteristics, microstructure and dielectric properties of the dielectric ceramics were investigated. The results show that (NaLn)Cu₃Ti₄O₁₂ (Ln=Ce; Nd) ceramics are single-phase ceramics. The dielectric constant of (NaLn)Cu₃Ti₄O₁₂ ceramics increasesand the dielectric loss changeswith the increase of sintering temperature. Different doping ions caninduce the corresponding polarization mechanism, further causingdifferent dielectric properties. (Na_1/3Ce_2/3)Cu₃Ti₄O₁₂ ceramics prepared at 1 000 ℃ havethe higher dielectric properties, i.e., ε=50 552 at 10 Hz. However, the dielectric loss of (Na_1/2Nd_1/2)Cu₃Ti₄O₁₂ ceramics prepared at 950 ℃ is smaller, i.e., tanδ=0.09 at 10 Hz.

Allochroic effect of rare-earth molybdate materials is related to the reflection spectrum and the power distribution of illuminants. Based on the chromaticity, the power distribution of four standard illuminants (i.e., D65, A, F2 and F11) were compared for constructing the illuminant difference functions (IDF), indicating that a significant allochroic effect of the materials usually occurs between two illuminants with a great difference in the power distributions. The allochroic effect appears when the minimum reflectivity is near asharp peak of IDF, while the color difference is small asthe minimum reflectivity isfar away from the sharp peak. Rare-earth ions with a potential allochroic effect were selected based on the atomic characteristic absorption spectra, and rare-earth molybdate materials synthesized via solid-state reaction were used for the related experimental validation.

Activity is a main application characteristic that is closely related to the microstructure of light-burned magnesia. The light-burned magnesia was obtained via calcining macrocrystalline magnesite powder at 700-1 100 ℃. The cell parameter, grain size, crystallinity, specific surface area, pore diameter distribution, specific pore volume, average pore diameter, activity and microstructure of light-burned magnesia at different temperatures were characterized. The particulate structure of light-burned magnesia was investigated by thermogravimetry based on the non-isothermal reaction kinetics theory, and the mechanism of the particulate structure evolution with temperature and its influence on the activity of light-burned magnesia were further analyzed. The results show that the cell parameter a₀ of light-burned magnesia firstly reduces and then becomes stable, and the grain size increases while the specific surface area decreases gradually when the calcination temperature increases from 700 ℃ to 1 100 ℃. However, the activity of light-burned magnesia does not comply with this rule, and reaches the maximum value at 800 ℃. The thermal decomposition of macrocrystalline magnesite powder is controlled via the chemical reaction at the phase interface. The decomposition product, i.e., the light-burned magnesia 'pseudo' particles, is composed of magnesia microcrystals and connected a pore network structure. The sintering of magnesia microcrystals affect the "pseudo" particle structure of light-burned magnesia as the calcination temperature increases, thus affectingits activity. The sample light-burned at 800 ℃ has a smaller grain size, a lower crystallinity, a larger specific pore volume, and a largest average pore size due to the lattice adjustment, which is conducive to the penetration of the reactant solution into the particles and accelerates the reaction progression, leading to the maximum activity.

Sodium niobate(NaNbO₃)-based lead-free ceramics have attracted much attention in the pulse power capacitors due to their non-toxicity and superior energy storage properties. However, the large recoverable energy-storage density (W_rec) and efficiency (η) cannot be achieved simultaneously, thus restricting their commercialization. This work proposed astrategy of increasing the relaxation characteristics to improve the energy storage performance via constructing a local random field. The (1-x)(0.96NaNbO₃-0.04CaZrO₃)-xBi_0.5Na_0.5TiO₃ (x=0.05, 0.10, 0.15, and 0.20) antiferroelectric energy storage ceramics were prepared by a conventional solid-state method. The effect of Bi_0.5Na_0.5TiO₃ content on the phase structure, microstructure and dielectric, ferroelectric as well as energy storage properties of 0.96NaNbO₃-0.04CaZrO₃ ceramics was investigated. The results show that the microstructure of each ceramic is homogeneous and dense. The (1-x)(0.96NaNbO₃-0.04CaZrO₃)-xBi_0.5Na_0.5TiO₃ solid solution transformsfrom antiferroelectric orthorhombic P phase (x≤0.10) to antiferroelectric orthorhombic R phase (x≥0.15), accompanied by abroadening dielectric peak moving towards the lower temperatures as Bi_0.5Na_0.5TiO₃ content increases, thus having the representative relaxation characteristics. The 0.85(0.96NaNbO₃-0.04CaZrO₃)-0.15Bi_0.5Na_0.5TiO₃ ceramic has a maximum energy storage density W_rec of 1.614 J/cm³ and a high energy storage efficiency η of 83.97% under 260 kV/cm at room temperature. Besides, the ceramic exhibits a good temperature stability at 25-150 ℃ (the variation of W_rec less than 15%) and a high energy storage efficiency, which can be used as a promising material for high-temperature pulsed power capacitors.

Three silicon nitride ceramic balls were prepared via hot static pressing (HIP). In addition to some conventional sintering aids like Al₂O₃ and Y₂O₃, TiN, Fe₃Si and WC transition metal compounds were incorporated into the powder mixtures before ball-milling and HIP, respectively. The microstructures and mechanical properties of the silicon nitride ceramic balls prepared were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nano indentation (NI) analysis. The results indicate that TiN additive has an effect of suppressing the formation of Si₂N₂O during sintering. TiN and WC additives can promote the diffusion of Al and O into silicon nitride matrix during sintering, resulting in the formation of some sialon phase. However, Fe₃Si additive has little effect as mentioned above. TiN additive has an effect of refining the microstructure, thus obtaining a refined grain structure with an even size distribution. Fe₃Si additive tends to produce a microstructure of long-coarse-grain intersected and bridged frame filled by grains. WC additive leads to the development of an uneven microstructure containing the coarser and finer grains. Compared to the balls containing Fe₃Si or WC additives, the ball containing TiN additive has better mechanical properties, i.e., higher hardness and greater modulus of elasticity.

The electrolyte of the proton conducting solid oxide fuel cell is the key component affecting both the performance and the stability. In this study, B-site cation-doped BaCe_0.9M_0.1O_3-δ (BCM, M=Sc, Y, Zr, Nb) proton conducting ceramics are prepared via solid-state reaction approach. The effect of B-site doping on its sintering characteristics and mechanical properties are examined by material characterization and nanoindentation test. The results show that trivalent ion doping can promote the particle growth during sintering, while high-valent ion doping can inhibit the particle growth. In terms of mechanical properties, the Young's modulus of the doped BCM decreases with the increase of the ionic radius of the trivalent doping elements (Sc and Y), and decreases with the increase of the valence state of the different valent doping elements (Y, Zr, and Nb).