In this study, a facile in situ sintering method has been proposed for fabricating high strength lightweight mullite whisker network reinforced proppants. The effect of TiO2 on the microstructure, properties and fracture behaviours of the mullite whisker network was researched in detail. The addition of TiO2 promoted the formation of a modified mullite whisker network structure, which effectively improved the flexural strength. The sample containing 4 wt.% TiO2 exhibited an excellent flexural strength of 215.25MPa and low bulk density of 1.53 g/cm3 at 1400 ?C. The TiO2-added mullite whiskers mostly exhibited rod-like crystals with about 0.5- 0.8 ?m in diameter and 10-15 ?m in length. The as-prepared ceramic proppant showed excellent properties, such as low breakage ratio (2.19%under 52MPa), low density (1.36 g/cm3) and low acid solubility (2.28 wt.%).

Starch consolidation casting (SCC) technique was successfully employed to produce both porous alumina and graded porous alumina ceramics. The solid content in the alumina suspension was maintained at 40 vol.%, with potato starch varying from 5 to 15%. Structures of the porous alumina (monolithic) samples obtained by SCC and uniaxial pressing were compared. In addition, the influence of the SCC consolidation temperature and the starch content were evaluated in the monolithic samples, while the consolidation temperature and the number of layers numbers were evaluated in the graded samples. The lower SCC consolidation temperature resulted in lower linear shrinkage and a slight increase in total porosity due to the increased pore size. The compressive strength values for the monolithic samples ranged from 60 to 200MPa, which can be considered high when compared to previous works. The graded samples exhibited porosity variations across layers and interfaces were free of cracks and imperfections. Linear shrinkage was the same for the adopted consolidation temperature and the porosity was slightly higher for the 3-layer samples. They achieved strength of 60MPa with fracture mode parallel to the applied load.

The limited folding resistance of continuous silicon carbide (SiC) fibres hinders their application as flexible, foldable materials. With this objective in mind, the folding endurance and damage properties of the second (2nd) and third (3rd) generation continuous SiC fibre tows were investigated through repeated folding tests, optical microscope observation and tensile tests. These SiC fibre tows were disassembled from two-dimensional (2D) SiC fibre braided fabrics with varying braiding angles. The braiding process can alleviate the force on fibre tows during the textile forming process. The investigation of damage mechanisms and analysis of force conditions are instrumental in optimizing structural parameters. The research findings suggested that, in comparison to the 3rd generation continuous SiC fibres, the 2nd generation SiC fibre tows demonstrated higher resistance to repeated folding. In contrast, the 2nd generation fabrics exhibited slightly lower folding endurance values. After repeated folding, the SiC fibre tows in fabrics showed the highest strength losses near the braiding angle of 37.8? to 38.3?. In comparison, the SiC fibre fabric demonstrated the lowest folding endurance values (approximately 760 times) near the braiding angle of 41? to 42?. Considering factors such as folding endurance value, the strength loss rate of fibre tows and fabric strength loss rate, it can be concluded that SiC fibres in fabrics with large braiding angles exhibit optimal performance in terms of folding endurance.

High-entropy ceramic materials usually refer to the multi-principal solid solution formed by 5 or more ceramic components. Due to its novel ?high-entropy effect? and excellent performance, it has become one of the research hotspots in the field of ceramics in recent years. As the research system of high-entropy ceramics has gradually expanded from the initial rock salt oxides (Mg-Ni-Co-Cu-Zn)O to fluorite oxides, perovskite oxides, spinel oxides, borides, carbides and silicates, its special mechanical, electrical, magnetic and energy storage properties have been continuously discovered. Based on the basic principle of high-entropy materials, this paper mainly introduces the prominent perovskite-type oxide high-entropy ceramics in recent years from the perspective of ceramic structure and properties, and predicts the development trend of high-entropy perovskite-type ceramics in the next few years.

Cu2+ and Er3+ doped BaZr0.05Ti0.95O3 (BZT) ceramics were prepared using the solid-state reaction method, where amount of CuO + Er2O3 was fixed at 2 wt.% and different CuO : Er2O3 molar ratios (i.e. 1:1, 1:2, 1:3, 2:1 and 3:1) were used. The influence of Cu2+ and Er3+ doping on crystal structure and dielectric properties of the samples sintered at 1300 ?C was investigated. X-ray diffraction analysis confirmed the formation of a single-phase material and tetragonal crystal structure with P4mm symmetry. Microstructural analysis conducted with a scanning electron microscope revealed well-defined and uniformly distributed grains across the surface of the sintered samples and reduction of grain size and density with doping. The highest energy storage density of 40.51mJ/cm3 with an energy efficiency of 78.8% was obtained in the sample with CuO : Er2O3 molar ratio of 2:1. The doped BZT ceramics have high dielectric constant and significantly lower tangent loss in comparison to the undoped BZT. The dielectric data confirm the non-Debye behaviour for all the samples. Impedance spectroscopy and electrical modulus analysis indicated that conduction in the materials was influenced by both the grains and grain boundaries. The AC conductivity is described by the Jonscher?s universal power law, whereas DC conductivity follows a dependency based on the Arrhenius?s theory. The results revealed a conduction mechanism characterized by non-overlapping small Polaron tunnelling up to 340?C and a transition to correlated barrier hopping conduction above 340?C within the selected temperature range for all the samples. According to the Arrhenius fitting of DC conductivity the activation energy of the undoped BaZr0.05Ti0.95O3 sample is 0.168 eV and decrease with doping to 0.138 and 0.131 eV for the sample with lower Cu2+ contents (CuO : Er2O3 molar ratios of 1:2 and 1:3, respectively).

LiTaSiO5 system is considered as type of solid electrolyte with great potential for application as ionic conductor. It is well-known that it is difficult to obtain pure dense LiTaSiO5 phase by traditional synthesis methods, because dielectric LiTaO3 phase easily precipitates during synthesis, which affects ionic conductivity. In this work, a glass-ceramic electrolyte with main LiTaSiO5 phase was obtained by controlled crystallization of Li2OTa 2O5-2 SiO2 glass without porosity. The precipitation of LiTaO3 phase at the grain boundary was effectively inhibited by adding an appropriate amount of ZrO2. Among all the glass-ceramic samples, the glass containing 4.76mol% ZrO2 had the maximum ionic conductivity of 8.40 ? 10?6 S/cm at 25?C, which is two order of magnitude greater than the ionic conductivity of the matrix glass. These glass-ceramic samples have the potential to be used as solid electrolytes in electrochemical applications.

In this work, the effect of bi-substitution of Zn and Ce at Cu and Ti sites on microstructure and dielectric properties of CaCu3Ti4O12 ceramics was investigated. The doped CaCu3-xZnxTi4-xCexO12 (CCZTC-x) powders (where x = 0.1, 0.2 and 0.3) were successfully synthesized via semi-wet route and the corresponding ceramics were obtained by sintering at 950 ?C for 14 h in air. The presence of major cubic CaCu3Ti4O12 phase along with minor secondary CuO phase was observed by X-ray diffraction analysis. Scanning electron microscopy analyses confirmed microstructure consisting of cubic-shaped grains and grain sizes of 0.76, 0.87 and 0.98 ?m, for the ceramics with x = 0.1, 0.2 and 0.3, respectively. The high value of relative dielectric constant of 1500 at 100Hz was found for the sample with x = 0.3, which may be regarded as having semiconducting grains surrounded by insulating grain boundaries. In addition, conductivity of the sintered samples decreases with doping concentrations and the activation energies of the samples with x = 0.1, 0.2 and 0.3 are 0.93, 0.76 and 0.74 eV, respectively.

The aim of the work was to determine the influence of metallic phase content on the obtained properties of hybrid composites from the ceramics-metal system. Six series of samples from three systems (Al2O3-Cu, Al2O3- Cu-Ni and Al2O3-Cu-Cr) with two different contents of metallic phase (2.5 and 10 vol.%) were prepared by uniaxial pressing and pressure-less sintering. The research carried out in this work used the classic idea of material engineering, assuming the optimization of the material?s functional properties by shaping the microstructure in a suitably modified technological process. The possibility of producing composite samples with density exceeding 95%TD was confirmed. There was no significant effect of the composition and the share of the metallic phase on the obtained values. The microstructure observations showed that the addition of the second metallic component had a positive effect on the size of the metallic particles, limiting the formation of metal clusters of significant size visible in the case of Al2O3-Cu samples. Compressive strength tests have shown that the addition of the second component to the metallic phase has a positive effect on the compressive strength of the material.

Novel tungstate SrLa6-xW10O40: xEu3+ (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15, 0.18, 0.21) red phosphors were prepared by solid state method at 1150 ?C by using SrCO3, La2O3, WO3 and Eu2O3 as raw materials. The powders were agglomerated with particles having mostly spheroidal morphology, mean particle size D50 = 12.8 ?m and narrow particle size distribution. With the increase of doping amount x, there is no significant difference in the diffraction peak position of the phosphor, but the cell volume of SrLa6W10O40 slowly decreases. The relative strength of diffraction peaks decreases gradually and the half-peak width widens gradually, indicating that the inclusion of Eu3+ ions affects the crystallization of the SrLa6W10O40 matrix. Excitation and emission spectra of the prepared samples were obtained. The optimal doping content has the SrLa5.85W10O4: 0.15Eu3+ phosphor and is characterised with the colour coordinate of (0.652, 0.348), which is closer to the red standard colour (0.67, 0.33) than the near-ultraviolet red phosphor Y2O2S: Eu3+ (0.622, 0.351) used for commercial LED.

In this work, ZnO-based powders were synthesized by a simple biosynthesis method using matoa leaf extract and microwave irradiation. The pure ZnO was modified with selenium doping (5, 10 and 15 at.%) to improve the photocatalytic capability in degrading 4-nitrophenol. The synthesized powders had wurtzite structure and XRD analysis demonstrated a change in ZnO lattice parameters with Se doping. Granular surface morphology and decrease in particle size with Se doping were observed by using FESEM. Meanwhile, EDX confirmed the presence of Zn, O and Se elements in the doped samples and BET analysis showed that the specific surface area ranged from 10 to 18m2/g. The observed strong absorption in UV region decreases with Se doping from 367 to 357 nm and is accompanied by an increase in the bandgap energy from 3.14 to 3.23 eV. Under UV irradiation, the ZnO powder doped with 5 at.% Se revealed the highest degrading reaction rate of ?0.0218min?1 and photocatalytic efficiency of 88.4% compared to other samples. Therefore, it was shown that an optimal amount of Se and simple biosynthesis route can enhance the photocatalytic capability of ZnO.