Zirconia, attributable to high strength, toughness, hardness, and excellent wear resistance, as well as favorable biocompatibility, has been increasingly and widely applied to dental restoration. However, the phase transformation toughness of zirconia ceramics improves at the cost of service life deterioration. And zirconia ceramics may suffer failure and fracture after long-term mastication in the oral surroundings due to frequent changes in temperature and masticatory force, especially in the extremely complex biochemistry surroundings, such as fairly moist oral cavity and saliva. The research progress of zirconia ceramics in the field of dental restoration, toughening theories and their research state of dental ceramics were reviewed. This paper also summarized the issue of toughening degradation which is occurred in clinical application, and elucidated the mechanism and approaches. With the enhancement of comprehensive mechanical properties and the future demand for healthy functionalization, zirconia ceramics will be more widely applied in the biomedical field.

Aluminum oxynitride (AlON) powders were synthesized by carbothermal reduction and nitridation process using α-Al₂O₃ powder as starting material. Activated charcoal powder and submicron carbon powder were mixed with α-Al₂O₃ respectively to vary nucleation density of AlON. Influence of nucleation density on phase assemblages, morphology of AlON powders and transparence of AlON ceramics were studied. Single phase AlON powders were synthesized after holding at 1750℃ for 60 min with for both mixture powders of different nucleation density. The results show that the synthesized powders exhibit different morphology and milling property. The AlON powder synthesized by α-Al₂O₃ and activated charcoal mixture show irregular shape, loose structure and small particle size, due to its high nucleation density. Moreover, it is easier to mill the obtained AlON powder into small particle (0.93 μm). However, for the AlON powder synthesized by mixture of α-Al₂O₃ and submicron carbon powder, their grain grow obviously during the synthesis of the AlON powder, due to its low nucleation density with large near sphere particles close to 2.13 μm in diameter. Therefore, nucleation density plays a key role in controlling morphology, structure characteristics and milling performance of the AlON powders. Using the AlON powder synthesized by high nucleation density powders, high transparent AlON ceramics was fabricated by pressureless sintering at 1880℃ for 150 min, the maximum transmittance was ~76.5% (3 mm in thickness). It is 48.3% higher than that using AlON powder synthesized by low nucleation density powders. Therefore, for using α-Al₂O₃ as starting material to prepare AlON powder, high nucleation density is beneficial to AlON powder with small particle size and high sintering ability, which contributes to the high transmittance of AlON ceramics.

Textured ZrB₂-ZrC ceramics sintered by spark plasma sintering were analyzed. The results obtained by SEM and EDS demonstrate the formation of an amount of resultant ZrC phase and trace level of ZrO₂ and BN phases, due to the various reactions between starting powders and impurities. Compared with conventional methods in which TEM was used to analyze the orientation relationship between the phase and the primary phase, EBSD method in SEM can not only study the orientation relationship, but also study a large number of phase boundaries simultaneously to obtain statistical results, so as to avoid artificial selectivity. By using this method, three orientation relationships that may exist between ZrB₂ and ZrC phases, i.e. (011¯0)||(111)&[21¯1¯0]||[101¯], (112¯0)||(2¯02)&[0001]||[111], and (1¯21¯0)|| (2 2¯0)&[0001]||[110] were checked. It is determined that there is no specific orientation relationship between the two phases in this study, inferring that the ZrC phase formed with a homogeneous nucleation mode rather than an epitaxial nucleation.

β-eucryptite ceramics with zero coefficient of thermal expansion (CTE) were prepared via solid state reaction method, adding CaO-B₂O₃ glass (CB glass) as sintering aid. The thermal property of CB glass and the crystalline phase, micro-structure of β-eucryptite ceramic samples were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The results indicate that CB glass is a good sintering aid. It significantly decreased the sintering temperature of β-eucryptite ceramics (from 1300℃ to 1150℃) and increased the relative bulk density (from 93.3% to 97.5%). No micro-cracks were found in β-eucryptite ceramics aided with CB glass. β-eucryptite ceramics added with 4wt%, 6wt% CB glass possessed zero CTE of 0.02×10^-6/K and 0.4×10^-6/K ranging from room temperature to 200℃, respectively. However, a new phase LiAlO₂ with extremely high positive CTE appears in the β-eucryptite ceramics added with 8wt% CB glass which leads to a positive CTE of 3.46×10^-6/K.

Magnetic ZnFe₂O₄/halloysite composite (MHNTs) was synthesized by Sol-Gel process and its sorption behavior towards methylene blue (MB) was studied. Structure, morphology and magnetic property of MHNTs were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), fourier transfer infrared (FT-IR), and vibrating sample magnetometer (VSM). Static batch equilibrium method was used to investigate the adsorption behavior and mechanism of MB on MHNTs. The results show that ZnFe₂O₄ composites with 10~30 nm spinel type nanoparticles are well loaded on the surface of HNTs. The average grain size of nano-ZnFe₂O₄ is 19.1 nm calculated by Scherrer equation．MHNTs exhibit good paramagnetic and magnetic recovery properties. MB sorption of MHNTs follows pseudo-second order kinetic model and Langmuir thermodynamics model. MB sorption process is strongly affected by temperature, and higher temperature is beneficial for the adsorption of MB by MHNTs. Furthermore, MHNTs can be recovered effectively by magnetic field and the adsorption properties of MHNTs on 10 mg/L MB solutions hardly decreased after 5 times of repeated use.

Hierarchical MOR zeolite nanocrystallines with mesoporous architecture composed of 2~4 nm pores were synthesized via a simple hydrothermal route by adding surfactant CTAB as mesoporous template in the absence of organic co-solvent and zeolite seeds, in which the mesoporous volume and external surface area could be adjusted by changing the amount of CTAB. The largest external surface area and mesoporous volume were 191 m²/g and 0.17 cm³/g. Adsorption of mesitylene on the MOR zeolitic samples showed that only a small amount of adsorption could be found in the microporous mordenite, but a large amount of adsorption in hierarchical mordenite which presented the characteristics of typical IV isotherm indicating a mesoporous structure. Catalytic properties of the MOR zeolitic samples were investigated by benzylation reaction of mesitylene and benzyl chloride. Compared with the traditional microporous mordenite, the reaction conversion on the hierarchical mordenite increased ~7 times and the reaction apparent rate constant increased ~19 times. This property is due to the expansive external surface areas and mesopores volume in the hierarchical mordenite zeolite which can effectively improve accessibility of the bulky reactants to acid sites and mass transfer rate of big products, and greatly promote the catalytic efficiency of bulky molecules.

By adjusting composition of spinning solution and spinning time, CaSi₂O₂N₂:Ce/Tb, Eu stacking fluorescent fibers for white LEDs were prepared through multi-step electrospinning and gas-reduction procedures. The obtained samples were characterized by SEM, TEM, XRD, and PL. The obtained sample keeps fiber morphology, and assembles as film at macro level. TEM images show that the fluorescent fibers consist of nanocrystalline. XRD patterns demonstrate that CaSi₂O₂N₂ crystal can be prepared through nitridizing at 1300℃ for 1 h, and its phase can be maintained after doping CeTb/Eu ions. Both sides of the CaSi₂O₂N₂:Ce/Tb, Eu stacking fluorescent fiber mats emit different light under the N-UV excitation light. The Eu ion doping side exposed to the exciting light can effectively undercut the emitting light reabsorption process of the fiber-stacking mat. It demonstrates that white light will be emitted when CaSi₂O₂N₂:Ce/Tb, Eu fluorescent fiber stacking mats are applied in a white light emitting diodes with N-UV chip.

A novel NaTaO_3-xS_x catalysts were successfully synthesized by one-step hydrothermal method using Ta₂O₅ as starting material and Na₂S₂O₃ as sulfur source. Its catalytic mechanism and reaction process were tested by degradation experiment. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XRS), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and X-ray diffraction (XRD). The results showed that the as-prepared S-doped NaTaO₃ did not display obvious variations to the surface charge and micro-morphology of NaTaO₃. UV-Vis diffuse reflectance spectrum analysis indicated that S^2- partially substitute of O^2- ions in the lattice to form Ta-S-Ta bonds, and the light response range of the doped NaTaO_3-xS_x samples extends to the visible region. The results of degradation experiment indicated that NaTaO_3-xS_x exhibited much higher activity than that of pure NaTaO₃. The reason is that in the crystal lattice of NaTaO_3-xS_x, S^2- ions replace part of the O^2-ions, which form a mixed valence band energy levels. The results of GC-MS showed that the monohydroxylated species (m/z = 304) results in the production at m/z = 156, 226 and 276, which is further degraded into species of m/z = 212 and 156. Finally, the photogenerated oxidative species forming over S-doped NaTaO₃ catalyst surface further decompose these intermediates into the final carbon dioxide and some non-toxic inorganic products (SO₄^2-, NO₃^- and NH₄⁺). In addition, in a ten-time recycling test, S-doped NaTaO₃ displayed reliable recycling photocatalytic performance, whose photocatalytic efficiency kept at a high level and only existed very slight drop, due to the loss of photocatalyst during the reclaiming process.

Effect of gamma-ray radiation on magneto-optical properties of Pb-doped optical silica fiber before and after irradiation were investigated. The experiment results indicated that Verdet constants of the fiber samples at 660, 808, 980, 1310, and 1550 nm were 3.093, 1.676, 1.240, 0.705, and 0.538 rad/(T•m), respectively, larger than these of single mode fiber. Verdet constants decreased with the increase of wavelength. It increased by 20.82% at 660 nm. After the fiber samples being irradiated from 0.8 kGy to 5 kGy, Verdet constants of Pb-doped silica fibers increased with the increase of radiation dose. Especially, Verdet constant of Pb-doped silica fiber irradiated at 5 kGy is 41.94% larger than that of the un-radiation treated fiber, and increased by 33.04% for SMF with the same doses treatment. Verdet constant of the Pb-doped silica fiber can be increased by doping and radiation methods, which is of great significance in the field of current sensing.

Carbon materials exhibit excellent microwave absorbing properties. However, it is difficult to disperse carbon homogeneously in the ceramic substrate. In this study, carbon was introduced into AlN matrix by addition of phenolic resin followed by pyrolysis process. The effects of phenolic resin content on sintering behavior, microstructure, thermal conductivity and dielectric properties of AlN ceramics were investigated. It was found that phenolic resin derived carbon could effectively promote the densification of AlN ceramics and reduce the sintering temperature. Relative density of the AlN ceramics reached 99.26% after sintering at 1700℃ with addition of 3wt% phenolic resin. In addition, it was found that the presence of phenolic resin derived carbon can effectively improve the thermal conductivity of the ceramics. The dielectric properties were also improved due to the carbon films formed in the pores and at AlN grain boundaries. With addition of 6wt% phenolic resin, AlN ceramics showed high thermal conductivity of 135.1 W/(m•K) and excellent microwave attenuation properties (the dielectric loss was 0.3 at X-band), which were perspective candidates for possible applications in high power microwave vacuum electron devices.

Two kinds of SiC fibers with different microstructures were analyzed by XPS, XRD and Raman spectra. The electrical conductivities of the fibers were measured, and their dielectric and microwave absorbing properties at elevated temperatures were investigated. Research results show that KD-I SiC fiber with rich carbon layers possess higher complex permittivities and electrical conductivities than do SLF SiC fiber with Si-C-O phase, resulting in poor impedance match between free space and KD-I fibers. Simultaneously, due to poor dielectric loss of SLF fiber, two fibers display inferior absorbing performance with the reflection loss values of -3.2 dB and -0.3 dB at X band, respectively. With temperatures increasing, ε° and ε? of KD-I fiber sharply increase, while the complex permittivity of SLF fiber display a small increment. Complex permittivities of two fibers are up to 20.9-j25.0 and 5.0-j0.37 at 700℃. Microwave absorbing properties of two fibers degrade at elevated temperatures, mainly ascribed to deterioration of impedance match.

Effects of annealing temperature on the microstructure and electrochemical properties of A₂B₇-type La_0.33Y_0.67Ni_3.25Mn_0.15Al_0.1 hydrogen storage alloys were systematically investigated by XRD, SEM, EDS, and electrochemical measurements. Results showed that the alloy was composed of CaCu₅-type, 2H-Ce₂Ni₇-type, 3R-Gd₂Co₇ -type and 3R-Ce₅Cu₁₉-type phases. Both abundance and unit cell volume of Ce₂Ni₇-type phase increased gradually with the anneale temperature increase when the annealing temperature was lower than 950℃. CaCu₅-type and Gd₂Co₇-type phases disappeared at 950℃, but both abundance and unit cell volume of the Ce₂Ni₇-type phase maximized. When annealing temperature was higher than 950℃, Ce₂Ni₇-type phase decreased while Ce₅Co₁₉ type phase increased. The alloy, annealed at 950℃, had the lowest hydrogen desorption platform pressure (0.0192~0.087 atm), maximum hydrogen storage capacity (1.35wt%) and high electrochemical discharge capacity (371 mAh/g) with the maximum capacity retention S₁₀₀ at 89% after 100 cycle. The high rate discharge ability (HRD) of the annealed alloys were significantly improved, the alloy annealed at 950℃ had the best performance and HRD₉₀₀ was up to 83.4%. These well performances demonstrated that it is the hydrogen diffusion in the alloys that controls the high rate discharge.

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ(BSCF) powder was prepared via Sol-Gel method. Porous BSCF-xGDC(x= 30wt%, 40wt%, 50wt%) composite cathodes were prepared via wrapping BSCF powders with Ce_0.9Gd_0.1O_2-δ (GDC) sol. The phase composition of the composite cathodes, the morphology of the cross section of the cell, as well as the BSCF particles coated with GDC were characterized with X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy, respectively. The electrochemical performances of the composite cathodes were studied by impedance spectroscopy. The effects of the amount of GDC on the electrochemical performance of the composite cathode were studied by impedance spectroscopy. All results showed that the electrochemical performance of the composite cathode greatly improved. Electrode polarization resistance of the BSCF-40GDC was the minimum, with the value of 0.397 Ω•cm² at 650℃. The maximum power density of the single cell was 0.514 W/cm² with the values of Ohmic resistance at 0.257 Ω•cm² and the polarization resistance at 0.0588 Ω•cm², by using H₂+3%H₂O as fuel and air as oxidizing gas at 650℃.

TiO₂ varistors are typical electronic devices with nonlinear current-voltage property fabricated from TiO₂ ceramics. This study investigated the influence of Ge doping on the nonlinear coefficient α and the breakdown electric field E_B of TiO₂-Nb₂O₅-CaCO₃ varistor ceramics. TiO₂-Nb₂O₅-CaCO₃ varistor ceramics doped with Ge were successfully prepared by using traditional method of ball milling-molding-sintering. The electrical performance, including nonlinear coefficient α, breakdown electric field E_B, and leakage current J_L, was tested with a varistor-direct current-parameter instrument. Average barrier height Φ_B of each sample was calculated by relevant formula. Analysis of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and scanning transmission electronic microscopy demonstrated that Ge doping notably changed the microstructure of TiO₂-Nb₂O₅-CaCO₃ ceramics, thereby increasing α and decreasing E_B. When Nb₂O₅ and CaCO₃ doping content were 0.5mol%, the TiO₂-Nb₂O₅-CaCO₃ varistor ceramics doping with 1.0 mol% Ge exhibited high α (10.6), low E_B (8.7 V/mm), and highest Φ_B (1.73 eV), superior to previous published findings. Furthermore, Ge with low melting point as sintering aid could reduce the sintering temperature of the varistor ceramics, with optimal sintering temperature at 1300℃.

A two-step route was used to prepare SnO₂/ZnO composite hetero-nanofibers. In the first step, hierarchical SnO₂ nanofibers were synthesized by electrospinning; in the second step, ZnO nanospheres were fabricated in zinc acetate solution using water bath at 90℃. The morphology, structure and composition of SnO₂/ZnO composite hetero-nanofibers were characterized and analyzed by XRD, SEM, EDX, and XPS. SnO₂ nanofibers in the composite materials keep hollow and hierarchical structure with 300 nm in diameter. The diameters of ZnO nanospheres grown on SnO₂ nanofibers are 250-300 nm. Gas sensing properties of SnO₂/ZnO composite hetero-nanofibers were tested using a static gas testing system. Gas sensing properties of pure SnO₂ nanofibers and ZnO nanospheres were also studied to compare their gas sensing properties. The results show that SnO₂/ZnO composite hetero-nanofiber gas sensors exhibit excellent sensing sensitivity, selectivity and long-tern stability for (0.5-100)×10^-6 acetone at 350℃. N-N homotype heterojunctions, existed in the joint between ZnO nanospheres and SnO₂ particles in the SnO₂/ZnO composite materials, change the potential barrier height. The absorption capacity of SnO₂/ZnO composite materials increases greatly due to changes of the transport characteristics of electrons and holes, which results in the improvement of acetone sensing properties of SnO₂/ZnO composite materials.

Solid state lithium batteries based on garnet-type solid electrolytes face the problem of contact between the solid electrolytes and the solid cathodes, which deteriorates the cycle performance. Aiming to overcome such problem, the solid state batteries with the LiNi_1/3Co_1/3Mn_1/3O₂-based cathodes, the Li_6.4La₃Zr_1.4Ta_0.6O₁₂ ceramic electrolytes, and the lithium metal anodes were studied. For constructing the LiNi_1/3Co_1/3Mn_1/3O₂-based composite cathodes, three-kind carbons were used as electronic conducting additives. It is found that the batteries with cathodes containing vapor grown carbon fibers (VGCFs) show better cycle performance than those with granular Ketjen Black as well as Super P carbons. Analysis indicates that the VGCFs result in less side reaction at high charge potential than do other two electronic additives, leading to reduced carbonates that cause the increase of the internal cell resistance. These results suggest that stability of electronic additives has important influence on cycle performance of solid state lithium batteries.

A novel graphene aerogel with pore size less than 1 µm was synthesized by Sol-Gel method, in which Nafion was skillfully introduced as modifiers connecting graphene oxides (GO). Ethylenediamine was used to produce a chemically linked graphene hydrogel during reducing process, which can then be freeze-dried to remove the absorbed water to form graphene aerogel. Nafion in GO solution prohibits the re-stacking of individual graphene sheets during reduction and freeze-drying process. By the above method, the pore size of as-prepared graphene aerogel could be effectively controlled within 1 µm, much less than that of the traditional graphene aerogel (20- 100 µm). The new graphene aerogel with unique structure exhibited excellent properties, such as high specific surface area, high porosity, and better electrochemical properties. All data suggest that this graphene aerogel may have promising application prospect in the field of energy.