Transparent ceramics is one of the most important materials with combined properties of structural and functional ceramics. The development of transparent ceramics is based on the research and development of nano sciences and technology, and of advanced ceramic processing sciences and technology. It will be the key materials for national economic development and defense necessary with high technology needed. At the same time, the process of ceramics from traditional opaque to translucent and to transparent will refer to many basic science issues, especially, the relationship between microstructure (including pores, grain boundary, grain size, morphology and so on) and photophysical properties of materials is still not clear. Therefore, as one of the main developing field of inorganic materials, the development of transparent ceramics needs joint efforts from chemistry, physics, laser, and material scientists together. The current advance of transparent ceramics is reviewed in this paper.

Bone and enamel are typical biomineralized materials through organic matrix-mediated processes. The mineral phase in bone and enamel is mainly apatitic calcium phosphate, but their size, morphology and organization are depending on the different composition and property of the matrix in two tissues. This paper reviews the progress of biomineralization study of bone and enamel, in particular the current understanding on the hierarchical structure of the tissues, the self-assembly of matrix proteins and the mechanism of matrixmediated mineralization. The biomimetic synthesis of calcium phosphate for hard tissues repair and regeneration is also discussed.

Bioglass powders were treated with phosphatidyl cholines, and the interactions between bioglass and phosphatidyl cholines were studied by thermal analysis and fourier transform infrared spectroscopy (FTIR). The phosphatidyl cholines are adhered on the bioglass surface through weak interactions such as hydrogen bonds. Surface modification of bioglass particles improves the compressive strength of the bioglass/chitosan composites. SEM observation indicates a uniform distribution of modified bioglass particles in the chitosan matrix. The results suggest that the surface modification by phosphatidyl cholines can effectively enhance the interfacial interaction between bioglass particles and chitosan matrix.

The composite of nanocrystalline apatite coated rutile TiO₂ was prepared by soaking TiO₂ nanosized powders into the simulated body fluid (SBF) at 37℃ for the different duration times. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), highresolution transmission electron microscope (HRTEM), energy dispersive X-ray (EDX), fourier transform infrared (FTIR) spectroscope, inductively coupled plasma atomic emission spectrometer (ICP-AES) and N2 adsorption measurements. XRD result shows that the content of the apatite coated on the rutile TiO2 increases with prolonging the soaking time in the SBF. It is demonstrated that composite powders have included some apatite through the absorption peaks of the O-H and PO₄^3-of the apatite in the FTIR spectrum. ICP-AES result shows that Ca and P concentrations decrease with prolonging the soaking time in SBF. It is evident from the TEM and EDX that there is some apatite coated on the surfaces of the rutile TiO₂. HRTEM result indicates that the interplanar spacing of (211) of the apatite is 0.27nm and the diameter of apatite nanoparticles is about 40nm.

TiO₂ nanotube arrays were fabricated by anodization of titanium foils in the viscous nonaqueous electrolytes. Effects of anodization parameters on TiO₂ nanotube were intensively studied. The photo-electrochemical property of dye sensitized solar cell (DSSC) based on TiO₂ nanotube arrays was tested and the influence of TiO₂ nanotube morphology on the performance of DSSC was investigated. The result indicates that the growth of TiO₂ nanotube arrays with high aspect ratio depends highly on the nonaqueous solution which is enhanced by the applied potential and anodizing time. TiO₂ nanotube arrays with aspect ratio up to 313.6 are fabricated in 0.5wt%NH4F in glycerol glycol at 50V for 17h. DSSC based on TiO₂ nanotube arrays (fabricated in 0.5wt%NH₄F in glycerol at 40V for 13h)exhibits an open circuit potential of 0.723V, 2.15mA/cm² short circuit current density.

With tetrabutyl orthotitanate and nickel(Ⅱ) chloride hexahydrate as original materials and cetyltrimethylammonium bromide as a template agent, Ni-doped TiO₂ mesoporous material was successfully prepared by solid-state reaction. The textural properties of the materials were characterized by the X-ray diffraction, high resolution transmission electron microscope (HRTEM), N₂-physisorption at 77K, fourier transform infrared spectroscope (FTIR), Raman spectroscope and ultraviolet visible light spectroscope. The components of Ni-TiO₂ were determined by inductively couple plasma atomic emission spectrometry. The photodegradation properties of this material for methyl orange were detailedly investigated. The results show that nickel is incorporated into the framework of TiO₂ with content of 3.62wt%. Furthermore, Ni-doped TiO₂ with anatase phase is laced the wall with the amorphous grain boundary and crystallite with some defect structures and nickel oxides. For Ni-doped TiO₂ mesoporous material, the specific surface area of 102.4m²/g and the pore radii distribution centre of 2.4nm are obtained. At 298K, the rule of pseudo-first-order reaction and the concentration effect are found in the photodegradation process of methyl orange on the Ni-doped TiO₂ mesoporous material surface, where the reaction rate constant is two times higher than that on pure TiO₂.

Using Ti(OBuⁿ)₄ as the inorganic precursor, Pluronic F127 as the templating agent, and thiourea as the additive, mesoporous anatase TiO₂ thin films were prepared through sol-gel method coupled with evaporationinduced self-assembly (EISA) process. Scanning electron microscope, X-ray photoelectron spectra, N₂ adsorption-desorption, X-ray diffraction, and UV-Vis spectra were used to characterize the as-synthesized mesoporous TiO₂ materials. It is found that, apart from doping N, S elements into the TiO₂ lattice, the mesostructure of the TiO₂ thin films is changed by adding thiourea into the reactive solution. When the mole ratio of thiourea to Ti(OBuⁿ)₄ is 2.5%, the pore size of the synthesized mesostructured TiO₂ reaches 12.4nm, and the mesoporous TiO₂ sample shows the best UV photocatalytic activity in the degradation of the methyl organge (MO). When the mole ratio of thiourea to Ti(OBuⁿ)₄ is 5%, the absorption edge of the as-synthesized sample can be extended from 380nm to 520nm, and the sample exhibits the best visible photo catalytic activity in decomposing the Rhodamine B (RhB).

Effects of titanium surface oxidation on titanium-ceramic adhesion were investigated. Cast pure titanium was subjected to pre-oxidation and introduction of an intermediate layer of SnO_x by sol-gel process. Specimen surfaces were characterized by XRD and SEM/EDS. The adhesion between the titanium and porcelain was evaluated by three-point flexure bond test. A rutile layer is formed on the titanium surface after pre-oxidation. Failure of the titanium-porcelain with pre-oxidation treatment predominantly occurs at the titanium-oxide interface. Pre-oxidation treatment does not affect the fracture mode of the titanium-porcelain system. The rutile layer is more strongly bonded to the porcelain than titanium. The poor adhesion of the rutile with substrate is due to the thermal stress arising from the large lattice mismatch and difference in coefficient of thermal expansion between Ti and rutile during cooling. However, a thin and coherent SnO_x film with small spherical pores obtained after heat-treated at 300℃ serves as an effective oxygen diffusion barrier to improve titanium-ceramic adhesion. The SnO_x films change the fracture mode of the titanium-porcelain system and improve the mechanical and chemical bonding between porcelain and titanium, resulting in the increased bonding strength of titanium-porcelain.

A definition of central crack damaged zone (CCDZ) is introduced based on tension experiments of Ceramic Matrix Composites (CMCs). The width of the CCDZ is defined to equal the debond length and the effect of interface toughness is neglected. When the CMCs rupture, the stress carried by the fibers can be estimated by the mean fiber stress within the CCDZ. Furthermore, the rule of mixtures is modified. Considering that the interface properties control the fracture mode, two kinds of models are presented respectively for brittle and ductile fracture strength. The stress concentration factor and interface debond energy release rate are introduced and discussed. It indicates that both the above factors result in decline of the tensile strength as they increase. The predictions of the given formulae are in good agreement with experimental data.

Theory research of MSP（Modified Small Punch）creep test was performed based on the thin plate bending creep model and the theory formula of creep stress exponent was established. A numerical study was carried out to simulate MSP creep tests by using the finite element software MARC. The creep stress exponent adopted in the numerical simulation was compared with the evaluation result. It is found that differences are 1.6% and 2.7% for 12Cr1MoV steel and tungsten-alloyed 9% Cr steel, respectively. The difference between the MSP creep test result of SUS304 stainless steel and the traditionally uniaxial creep test result is only 2.9%. The validity of the theory formula is verified by the consistency of numerical simulation results and by the excellent agreement with the experimental results. Based on the research of the creep properties of Si₃N₄ ceramic, it is found that there are both preferable ductibility and obvious creep deformation at 1000℃. The creep stress exponent of Si₃N₄ ceramic is obtained by using the theory formula. The results indicate that the MSP creep test method has wide application for the evaluation of high temperature creep properties of nonmetal materials.

The oxidation behavior of MoSi₂ composites strengthened and toughened by Si₃N₄ particles and SiC whiskers was investigated. The oxidation performances of pure MoSi₂, MoSi₂-Si₃N_4(p) and MoSi₂+20vol%Si₃N₄+20vol%SiC at 773K were analyzed by thermo gravimetric analysis(TG). The surface micrograph and phases of the oxidation productions were analyzed using by SEM and X-ray. “Pesting” phenomena are observed in the pure MoSi₂ and MoSi₂+20vol%Si₃N₄ after oxidation, the relationship between gain weight and oxidation time is followed the straight-line law. The oxidation layer is loose and the main oxidation production is MoO₃. While the relationship between the gain weight and oxidation time is followed parabolic law during the oxidation of MoSi₂+40vol%Si₃N₄ and the oxidation rate is 0.04mg²/(cm⁴·h). The oxidation layer is dense and the main oxidation productions are SiO₂ and Si₂N₂O. So the resistance to “Pesting” oxidation will increase with the content of Si₃N₄ increasing. There happens serious “Pesting” in the MoSi₂+20vol%Si₃N₄+20vol%SiC after oxidation and the main oxidation production is short acicular MoO₃.

Spinel and spinel-zirconia composite powder were synthesized by soft chemistry method using ［AlO₄Al₁₂(OH) ₂₄(H₂O) ₁₂］⁷⁺（abbreviated Al₁₃） as aluminum source. Precursor structure, reaction progress and material microstructure evolvement were characterized by ²⁷Al NMR, XRD, DSC-TG and FTIR. Spinel precursor was prepared by mixing Al₁₃ solution and magnesium slurry which was obtained by milling the mixture of MgCl₂·6H₂O and NaOH, and its component included Mg₆Al₂CO₃(OH)₁₆·4H₂O and β-Al(OH)₃. Spinel is formed from calcination of this spinel precursor at 600℃ for 1h, and only spinel is formed at even higher temperatures. Spinel-zirconia composite powder precursor is prepared by hydrolysis-precipitation process of Al₁₃, MgCl₂·6H₂O and ZrOCl₂·8H₂O solution. Spinel-zirconia composite powder can also be obtained from calcination of the precursor at 600℃. FTIR spectra of the Al₁₃ powder and spinelzirconia precursor show that the ［AlO₆］ absorption band shifts from 608cm^-1 to 601cm^-1 and ［AlO₄］ from 761cm^-1 to 723cm^-1.The result shows that Al₁₃ has obvious advantage in synthesis of spinel and spinelzirconia composite powders at low temperature because Al-O-Mg bond can be formed easily in precursors.

Two dimensional carbon fiber-reinforced silicon carbide-carbon binary matrix composites (2D C_f/(SiC-C)) were fabricated by means of isothermal and isobaric chemical vapor infiltration (ICVI). The matrix structures of the 2D C_f/(SiC-C) composites were characterized by the backscattered electron imaging (BSE) of scanning electron microscope (SEM). Furthermore, their room temperature mechanical properties and fracture surfaces were compared with two dimensional carbon fiber-reinforced silicon carbide matrix composite (2D C_f/SiC). The results indicate that the matrices in the 2D C_f/(SiC-C) composites are multilayered structures composed of SiC and PyC layers. The PyC matrix layers are homogeneous and continuous, which are bonding well with SiC matrix layers. The 2D C_f/(SiC-C) composite with a thicker PyC matrix layer in fiber bundles exhibits better mechanical properties. Meanwhile, its tensile strength, failure strain, fracture toughness and fracture work are 3%, 142%, 22% and 58% higher than those of the 2D C_f/SiC composite, respectively. The multilayered matrices composed of SiC and PyC layers, cause the fibers in the 2D C_f/(C-SiC) composites to pull out twice in a concentrated mode. Moreover, the first pull-out fibers play a leading role in enhancing the strength and toughness.

Zirconium-containing carbon fiber preform was prepared by ZrOCl₂ aqueous solution impregnation. ZrC modified carbon/carbon (C/C) composites were obtained by a series of procedures combined with densification by thermal gradient chemical vapor infiltration (TCVI) and high-temperature graphitization. The ablation properties were tested in an oxyacetylene torch. The phase composition and morphology of the composites were investigated by XRD and SEM, respectively. Results show that, with increasing ablation times, the linear and mass ablation rates increase firstly and then decrease, remain constant finally when ZrO₂ is not removed after each ablation. Meanwhile, the linear and mass ablation rates increase with the ablation time in case of removing ZrO₂ after each ablation. The evaporation of ZrO₂ will absorb heat and relieve erosion from oxyacetylene flame on the ablated surface of the specimen, and also accelerate the mass loss of the specimen, which leads to the decrease of the linear ablation rate and increase of mass ablation rate of the composites.

Carbon/carbon (C/C) composites are one of the most important high temperature structure materials; Which are oxidized remarkably above 400℃ in oxidative atmosphere. In order to improve the oxidation resistance of C/C composites, suspension mixtures prepared by mixing B₄C, SiC and Al₂O₃ powders and phosphoric acid solution were used as precursors to modify the C/C composites by a novel hydrothermal treatment. The influences of the hydrothermal treatment temperature on the phase, microstructure and antioxidation property of the as-modified composites were investigated. The asmodified C/C composites were characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscope (PDS) and X-ray photoelectron spectroscopy (XPS) techniques. Results show that the surface of the C/C composites is covered by a coating composed of molten B₂O₃, HPO₃ and microcrystalline Al(PO₃)₃ after modified by the hydrothermal treatment, and their oxidation resistance is effectively improved in the temperature range from 120℃ to 200℃. The anti-oxidation property of the treated C/C composites is improved with increasing hydrothermal treatment temperature. The mass of the modified C/C composites losses only 2.31% after oxidized at 700℃ in air for 10h.

A new A site complex lead-free ferroelectric ceramics of (1-x)Bi_0.5(Na_0.82K_0.18)_0.5TiO₃-xBiCrO₃(BNKT-BCx) was prepared by a conventional solid state reaction method and dielectric properties of the system in the temperature from room temperature to 500℃ were investigated. It can be evidently seen that there are two abnormal dielectric peaks and a dielectric loss peak with increasing temperature. The dielectric constant near temperature of low abnormal peak has obvious frequency dependence, and Curie temperature shifts insignificantly with increasing frequency, which is different from the characteristics of typical relaxor ferroelectrics. It suggests that relaxor ferroelectrics can be divided into the intrinsic relaxor ferroelectrics and extrinsic relaxor ferroelectrics. The frequency dependence near the temperature of low dielectric peak is extrinsic relaxor which is created by space charges and defects dipole by using the ε_r-T curves of poled and unpoled samples.

ZnAl₂O₄-Mg₂TiO₄-CaTiO₃ ceramics were prepared by the solid-state reaction. The effects of CaTiO₃ on phase compositions, microstructure and microwave dielectric properties were investigated. It shows that CaTiO₃ can effectively improve the sinterability of the ceramics and lower the densification temperature by about 150℃. ZnAl₂O₄-based spinel, CaTiO₃, MgTi₂O₅ and Zn₂Ti₃O₈ phases are included in the ZnAl₂O₄-Mg₂TiO₄-CaTiO₃ system, however, Zn₂Ti₃O₈ phase disappears when the sintering temperature is higher than 1400℃. As CaTiO₃ content increases, CaTiO₃ phase in the sintered body raises while MgTi₂O₅ phase reduces. Furthermore, CaTiO₃ can adjust obviously the temperature coefficient of resonant frequency of the (1-x)ZnAl₂O₄-xMg₂TiO₄(x=0.21) ceramics. When 6mol% CaTiO₃ is added to the (1-x)ZnAl₂O₄-xMg₂TiO₄ (x=0.21) system, a temperature-stable microwave dielectric ceramics sintered at 1400℃ with an ε_r of 11.8, a Q·f of 88080GHz and a τ_f of -7.8×10^－6/℃ can be obtained.

Normal four-layer-Ba_0.6Sr_0.4TiO₃ (BST) films and two new types of BST films were prepared on Pt/Ti/SiO₂/Si substrates by sol-gel method. For the first new type of films composed of four layers, the first layer was preheat-treated (PT) in the preparing process; while for the second new type of films consisted of eight layers, odd layers were alternate-preheat-treated (APT) in the preparing process. The effects of PT and APT on the dielectric properties of the BST films were studied. Scanning electron microscope (SEM) and atomic force microscope (AFM) were used to observe the film surface topography and particulate formation, X-ray photoelectron spectroscope (XPS) was performed to examine the film composition chemical states, and HP4284Atype LCR was employed to study the film dielectric properties. It is shown that the normal BST films display bad dielectric properties, whereas the BST films PT are smooth and compact with no crack or shrinkage cavity and significantly reduce surface non-perovskited structure, which indicates obviously the improvement of dielectric properties. Also, the BST films APT are more significantly improved in topographies, made up of nanocrystal grains about 30nm in average size and show more decrease of non-perovskited structure, and reveal lower dielectric loss and more enhanced dielectric stability and strength, satisfying actual application demands in low frequency field. In addition, the effects of annealing temperature and film thickness on the film structure and dielectric properties are discussed.

The superparamagnetic CoFe₂O₄ nanoparticles with core size of 510nm were prepared by high temperature polyol process using FeCl₃·6H₂O, CoCl₂·6H₂O and HOOC-PEG-COOH as reactants. The samples had good monodispersibility in aqueous solution. Moreover, the influences of reaction conditions such as varieties of modification agents and their amounts, reaction temperature and time on the size, dispersibility and magnetic properties of CoFe₂O₄ nanoparticles were investigated. The results indicate that choosing the modification agent with strong polar group, increasing the amount of modification agent, elevating reaction temperature and extending reaction time are beneficial to obtain samples with larger particle size, better waterdispersibility and narrower size distribution. The optimum reaction condition is determined as follows, the weight ratio of metal source to HOOC-PEG-COOH is 1∶10, reaction temperature is 210-220℃ and reaction time is 2h. Magnetic analysis shows that all the samples manifest a well-defined superparamagnetic behavior at room temperature. The larger the particle sizeis is, the higher saturation magnetizationis is.

Ni_0.35Zn_0.65Fe₂O₄ were respectively prepared by self-propagating hightemperature synthesis (SHS) method in two different conditions. The reactions of Fe, Fe₂O₃, ZnO, NaClO₄ and various Ni-containing species (Ni, NiO, NiCO₃) were carried out in air and in the presence of an external magnetic field of 1.3T. The combustion temperature was measured by infrared thermo detector. SHS products and sintered end-products were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometry (VSM). The results show that Ni_0.35Zn_0.65Fe₂O₄ synthesized using Ni and NiO as nickel sources have better magnetic properties with no miscellaneous phase, lower coercivity and the larger specific saturation magnetization, than the products synthesized using NiCO₃ as nickel sources which contain impurity phase and have bad magnetic properties. The specific saturation magnetization of Ni_0.35Zn_0.65Fe₂O₄ in 1.3T magnetic field is improved. Nickel powder can replace nickel protoxide as nickel source to synthesize nickel zinc ferrite by SHS.

A MoSi₂-SiC-Si coating was prepared by in situ reaction method. The phase composition and microstructure of the coating were studied by using XRD,SEM and EDS analysis, and then the anti-oxidation property of the coating was investigated. The results show that the thickness of obtained coating is about 120μm, and the main phases are composed of MoSi₂, SiC and Si. The MoSi₂-SiC-Si coating has excellent anti-oxidation property, which can protect C_f/SiC composites from oxidation at 1500℃ in air for 96h, the weight loss of the coated samples is only 1.8%. The weight loss of the coated C_f/SiC composites samples is primarily due to the reaction of C_f/SiC composites substrate and oxygen diffusing through the penetration cracks in the coating.

Lanthanum-cerium oxide (La₂Ce₂O₇, LC) thermal barrier coatings (TBCs) were prepared by atmospheric plasma spraying (APS). The actual composition of the as-sprayed coating is La₂Ce_1.66O_4.32, due to the volatilization of CeO₂ phase during the spray process. A little decomposition of the LC coating takes place after annealing at 1400℃ for 240h. The thermal conductivity of bulk LC material is about 0.51W/(m·K) at 1000℃, which is one fourth of that of typical bulk YSZ. The coefficient of thermal expansion (CTE) of the LC coating ranges from 10×10^-6K^-1 to 13×10^-6K^-1 at the temperature from 450℃ to 1100℃, which is relatively higher than that of the YSZ coating. Dilatometric measurements show that there is slight shrinkage in the coating till 1250℃, however, a remarkable sintering process happens cluring holding period at 1250℃. A spallation of the LC TBC occurs after 60 cycles at 1100℃ by typical delaminating cracking within the LC topcoat.

Iron nitride nanocrystallines with core/shell structure were synthesized by solvothermal method using FeCl₂·4H₂O as Fe source, NH₄Cl and NaN₃ as mixed nitrogen source. XRD, TEM and HRTEM were adopted to characterize the phase composition morphology, and core/shell structure of the final product, respectively. The mechanism of the formation of Fe₄N nanocrystallines with core/shell structure were discussed based on the XRD analysis. The effects of temperature, reaction time and feeding order in the experiment and the magnetic property were studied. The results indicate that Fe₄N nanocrystallines with core/shell structure can be prepared in xylene at 400℃ through the precise control of the feeding order. Because of core/shell structure of the product, the maximum value of the specific saturation magnetization of the iron nitride nanocrystal is lower than the value reported by reference.

Carbon nanotube microspheres with regular shape were fabricated from acid-treated and aminefunctionalized carbon nanotubes (CNTs) using reverse microemulsion. The effects of the oil system with different molecular weight, the content of CNTs in ammonia water, the extent of acid treatment, and the stir temperature for emulsion on the formation and morphology of CNTs microspheres were investigated, meanwhile the mechanism of CNTs microspheres formation was studied. It is found that using CNTs acid treated for 1.5h, CNTs microspheres with a diameter of 2-20μm are synthesized after vigorous stirring in castor oil system at 85℃. In addition, with increasing the contents of CNTs in ammonia water from 0.27% to 0.55%, the fabricated microspheres become larger, and their surfaces become more compact.

The Cd-doped ZnO nanotubes with Cd content of about 3.3at% were synthesized via a process of evaporating mixture of pure Zn and Cd powders and then oxidating in a wet condition. Field-emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) analysis indicate that most of the nanotubes are of about 80-150nm in outer diameter, several micrometers in length, and about 20nm in wall thickness. Compared with photoluminescence (PL) spectra of the pure ZnO nanostructures prepared in the same condition, the room-temperature ultraviolet (UV) near-band-edge (NBE) emission of the Zn_1-xCd_xO nanotubes exhibite a slight red shift from 3.26eV to 3.20eV, which is attributed to Cd substitution. It is suggested that the growth of the Zn_1-xCd_xO nanotubes follow vapor-liquid-solid (VLS) mechanism, and a possible growth process of the Zn_1-xCd_xO nanotubes is put forward. The Kirkendall effect is considered to play an important role in the formation of the Zn_1-xCd_xO nanotubes.

Using template PEG as structure directing agent and urea as the precipitant, alumina microfibers with mesoporous structures were successfully synthesized from a hydrothermal preparation and thermal-decomposition of precursor of ammonium aluminum carbonate hydroxide (denoted as AACH), and its adsorbability was also investigated. The phase state, chemical structure, surface morphology, special surface areas and mesoporous structure of the synthesized alumina microfibers were characterized systemically by means of XRD, SEM, TEM, TG/DTA, and N₂ adsoption-desoption techniques, respectively. The adsorptive property of the obtained mesoporous alumina fibers was examined by using a typical SCR(Selective Catalytic Reduction) denitrification facility. The results show that the AACH microfibers with diameter of about 200-300nm and length up to 8μm or 10μm are prepared by using PEG as template. The mesoporous η-Alumina microfibers with specific surface area 316m²/g and average pore diameter 2.5nm are obtained after calcined at 900℃ for 2h, and the morphology is retained in the calcination process. SCR denitrification tests show that the as-prepared mesoporous alumina microfibers exhibit more favorable adsorptive property and its efficiency of denitrification increases approximately 15% compared with commercial γ-Al2O3 powder.

Nano-powders of Co_0.8Mn_0.8Ni_0.9Fe_0.5O₄ NTC (Negative Temperature Coefficient) thermistor materials were prepared by co-precipitation method with NH₄HCO₃ as precipitator. The effects of calcination temperature on the material phase were studied. The influences of different sintering processes on the microstructure and thermal sensitive characteristics of NTC thermistor materials were investigated. The samples were characterized by XRD, TG/DTA, FT-IR, SEM, and Laser Particle Size Analyzer. The results show that the powders calcined at 750℃ are single spinel, the grain size of the powders is about 32.1nm, and the particle size is about 50-100nm. The samples possess better electrical properties: ρ_25℃=1183Ω·cm, B_25/50=3034K under the process conditions of constant temperature 840℃ and 1200℃ for 2h respectively, the heating and cooling rate of 1℃/min. It is found that proper sintering process can effectively improve the microstructure and thermal sensitive properties of the NTC thermistor materials. According to the calculation from the slope of lnρ-1/T curves, the activation energy is about 0.26eV.

In order to obtain the NTC thermistors with small B constant (about 1900K), applied to wide temperature range, Mn0.43Ni0.9CuFe0.67O4 NTC thermistor materials prepared by Pechini method were microwave-calcined at different temperatures (650℃, 750℃ and 850℃). The calcined Mn_0.43Ni_0.9CuFe_0.67O₄ powders were pressed and then sintered at 1000℃ in a microwave furnace (multimode cavity, 2.45GHz).The crystal structure, phase compositions, morphology and particle size distribution of the samples were analyzed by FT-IR, X-ray diffraction (XRD), scanning electron microscope (SEM) and a laser particle size analyzer. The experimental results show that the electrical properties of the ceramics are strongly dependent on the calcination and sintering process. The application of microwave leads to a lower calcination temperature (650℃) and densified uniform microstructures. Microwave sintering can obtain the components with well uniformity of B constant and resistivity, of which the Bavg. is 1930K (deviation of 0.31%) and resistivity ρ_avg. is 135Ω·cm (deviation of 4.55%). However, the B_avg. is 1720K (deviation of 1.47%) and resistivity ρavg. is 78Ω·cm (deviation of 25.34%) for the conventionally sintered components. From complex impedance analysis, the grain resistance (R_b) and grain boundary resistance (R_gb) are respectively 255Ω and 305Ω for the microwavesintered samples. The R_b and R_gb are respectively 200Ω and 230Ω for conventionally sintered samples.

A pair of chromophores with donor-acceptor properties, coumarin-3-carboxylic acid (3-CCA) and 9-anthracene carboxylic acid (9-ACA), were intercalated into the layered double hydroxide (LDH), ［Zn_0.66Al_0.34(OH)₂］(CO₃) _0.17·0.33H₂O by the method of ion-exchange procedures in ethylene glycol. The co-intercalation compounds with different molar ratios of donor to acceptor in the solid products were obtained by controlling ion-exchange time, temperature, and the molar ratio of donor to acceptor in the solution. The obtained co-intercalation compounds were characterized by X-ray diffraction, infrared and thermogravimetry techniques. The photochemical properties of the obtained compounds were studied by UV-Vis absorption and fluorescence spectroscopy. These results indicate that the pair of chromophores, 3-CCA and 9-ACA within the interlayer region of the host can give rise to energy transfer processes because of the characteristics of their excited states.

Poor stabilities of synthesized mesoporous sieves inhibit their applications. In present work nanosized high crystalline mineral, natural montmorillonite, was introduced into the synthetic system in order to improve the stability of mesoporous sieve. Two additional siliceous sources, Na₂SiO₃ and nano-sized white silica, were employed to widen the gallery space of montmorillonite into nano-scale. The resultant mesoporous montmorillonite was charactered by XRD, FTIR, TEM and N₂ adsorption-desorption isotherms. Moreover, the influences of milling conditions, stirring time, and type of siliceous sources on the porous structures and the hydrothermal stabilities of mesoporous montmorillonite were also discussed. The results show that intensive milling of raw materials is necessary to achieve longrange ordered mesopores in the structure. Furthermore, the multi siliceous sources make significant improvements on the hydrothermal stabilities of the samples, due to the cooperation effects between the Na₂SiO₃, white silica, and montmorillonite sheets. The highest hydrothermal stability exists in the sample synthesized from multi siliceous sources, whose original specific surface area is up to 772m²/g. After hydrothermal treatment for 10d, the sample keeps the long-range ordered mesoporous structure with specific surface area above 580m²/g.

Transparent and low thermal expansion Li₂O-Al₂O₃-SiO₂ glass-ceramics were prepared by addition of TiO₂ and ZrO₂ as nucleation agents. The effects of heat-treatment temperature and time on the crystallization, and phase transition behavior were discussed and the stabilities of microstructure and properties were investigated by DTA, XRD and SEM. Isothermal transformation curve of the LAS glass was also measured. The results show that β-quartz solid solution is stable in the temperature range from 750℃ to 900℃ and in long annealing time. Further more, LAS glass-ceramics have excellent stability in high temperature, which is still transparent and low thermal expansion after heattreated at 850℃ for 5h. The stability of structure and properties mainly attribute to the high nucleation efficiency of the TiO₂ and ZrO₂ mixed nucleation agents.

Large size CdWO₄ single crystals were grown by vertical Bridgman process. The crystal was characterized by DSC/TG, XRD, EPMA, optical transmittance and X-ray stimulated luminescence spectra. The melt volatilization in the growth and the chemical composition change of the crystal were analyzed and the optical homogeneity of the grown crystal boule was investigated. It is verified that a serious melt volatilization occurs in the crystal growth, in which CdO in the melt is more prone to volatile. The chemical composition of the grown crystal shows a cadmium lacking characteristics in varying degrees. A higher Cd/W ratio in chemical composition appears in the crystal grown in earlier period, while the Cd/W ratio decreases continuously in the crystal grown afterward. The crystal grown in later period shows somewhat a lower optical transmittance in the wavelength range of 380-550nm and a lower intensity of X-ray stimulated luminescence with a little red-shifted wavelength. By means of purifying the feed material, decreasing the melt volatilization and annealing in oxygen atmosphere, the crystals with better optical homogeneity may be grown by vertical Bridgman process.

Silicate glass of system SiO₂-B₂O₃-Al₂O₃-R’O-R₂O（R’=Ca, Mg; R=Na, K）was designed and melted for ion-exchanged integrated optical waveguide chip, on consideration of the suitability of ion-exchange and ion-diffusion process on this glass substrate, buried channel waveguide was manufactured by Ag⁺/Na⁺ ion-exchange in mixed melted salts, and subsequently field-assisted ion-diffusion process. Observation of optical microscope and electron microprobe show that Ag⁺ diffusion zone is driven to approximately 10μm under the glass substrate surface. The Ag⁺ diffusion zone possesses higher refractive index than glass substrate, and thus acts as the waveguide core. This waveguide core is typically in dimension of 8μm×8μm, matching well with that of single-mode-fiber core, which ensures a low coupling loss. Propagation loss and coupling loss with single-mode-fiber is measured to be 0.1dB/cm and 0.2-0.3dB/facet respectively, at the wavelength of 1.55μm. The propagation loss is very close to glass material inhere loss at the same wavelength, a typical characteristics of buried waveguide. It shows that the waveguide manufacturing process is promising for implementation of low-loss integrated optical devices.

To restrain the infrared emission of zinc ferrite in 8-14μm wave band, highly dispersed carbon coated ZnFeO nanocomposites were obtained from glucose solution under hydrothermal conditions, where ZnFeO particles prepared firstly in a simple hydrothermal route was used as the seeds. It was proved to be a core-shell structure of glucose-based carbon coated ZnFeO particles by transmission electron microscope (TEM), fourier transform infrared (FT-IR), and UV-Vis technologies. After heat-treated at 500℃, the carbonization degree of the coating is improved, but the core is still oxide. Whereas the core takes place a carbothermal reduction at 1000℃, it finally yields a structure with a graphite layer coated Fe nanocrystals. The infrared emissivity tests in 8-14μm waveband show that it can be lowered to 0.5 by the glucose-based carbon coating without the heat treatment. After heat-treated at 500℃, it lowers the average infrared emissivity further to 0.353, which will expand the stealth band of zinc ferrite.

Tungstentellurite glasses TeO₂-ZnO-Na₂O-WO₃ and tungsten-niobium-tellurite glassesTeO₂- ZnO-Na₂O-Nb₂O₅-WO₃ were investigated for the application in broadband Raman fiber amplifier. Effects of the addition of Nb₂O₅ and WO₃ on the thermal stability against crystallization and Raman spectra of tellurite glasses were discussed. The results suggest that the addition of Nb₂O₅ and WO₃ can largely improve the thermal stabilities of tellurite glasses. Moreover, the tungsten-niobium-tellurite glasses exhibits strong Raman peaks at around 862 and 921 cm^-1. The mid-high frequency Raman region of the tellurite glass co-doped by Nb₂O₅ and WO₃ expands from 550cm^-1 to 950cm^-1 with the maximum full width at half maximum (FWHM) of about 355cm-1, which indicates that the tungsten-niobium-tellurite are promising materials for broadband Raman fiber amplification.

Although the Lu₂Si₂O₇∶Ce(LPS∶Ce) has a high light yield about 26000ph/MeV, the LPS∶Ce crystals grown by Czochralski(Cz) process usually display a low light yield. In present work, annealing treatments in different conditions were carried out on Cz grown LPS∶Ce with low luminescence efficiency, in order to investigate the effect of annealing treatment conditions on scintillation properties of LPS∶Ce, such as luminescence efficiency, absorption spectrum. It is found that annealing in argon atmosphere has a negligible effect on the scintillation properties of LPS∶Ce; annealing in air can dramatically improve the luminescence efficiency of LPS∶Ce. The optimized annealing mechanism is determined through the comparison between different annealing treatment: atmosphere of air; annealing temperature of 1400℃; annealing time depending on the dimension of the sample. The larger dimension is the longer annealing time. The change trend of charge transfer band in the absorption spectrum and UV-ray excitation and emission property of LPS∶Ce crystal are also discussed.

Spherical-like (Y,Bi)AG∶Eu³⁺ red phosphor powders with good photoluminescence performance were synthesized by chemical coprecipitation method. By using DTA-TGA and XRD, both the thermal decomposition and phase formation of (Y,Bi)AG∶Eu³⁺ precursors were investigated in process of calcination. The crystal structures, surface morphology and luminescence properties of the phosphors with different Bi³⁺ contents were characterized by means of XRD, SEM and fluorescence spectrometer. The result shows that the pure YAG crystal phase is formed after calcination at 1000℃ or above. The photoluminescence intensity of YAG∶Eu³⁺ red phosphor strengthens with increasing Bi³⁺ content due to the sensitizing of Bi³⁺ to Eu³⁺，but decreases by excessive Bi³⁺ ions. When the Bi3+ content is 0.0010, the photoluminescence intensity reaches the highest. Addition of Bi³⁺ cannot change the crystal structure of YAG∶Eu³⁺ phosphor, which is garnet with a little different lattice parameter. The particles of (Y,Bi)AG∶Eu³⁺ red phosphor are spherical-like shapes, narrow size distributions with no aggregation.

YBO₃∶Eu³⁺ microspheres with flower-like structures were fabricated by a facile hydrothermal method. The composition, structure and morphology of obtained YBO₃∶Eu³⁺ were studied by means of XRD、EDX, HRTEM and SEM. The as-prepared YBO₃∶Eu³⁺ microspheres show hexagonal vaterite phase with the elements of Y, O, B, Eu to be found. The YBO₃ microspheres, with an average diameter of 1-2μm, are composed of nanosheets with thickness of 100nm. The formation mechanism of the flower-like structures is also proposed. The YBO₃∶Eu³⁺ samples have a strong red emission at 612nm and a high R/O ratio under ultraviolet excitation, which indicate lower symmetry of crystal field around Eu³⁺ in such flower-like structures.

LiCaBO₃∶Dy³⁺ phosphor was synthesized by solid-state method. LiCaBO₃∶Dy³⁺ phosphor shows several bands peaking at 484, 577 and 668nm. Monitoring at 577nm peak, the excitation spectrum has several bands peaking at 331, 368, 397, 433, 462 and 478nm. The emission spectrum and luminescence intensity of LiCaBO₃∶Dy³⁺ phosphor were investigated by varying Dy³⁺ concentration. The result shows that the ratio (Y/B) of yellow emission (577nm) to blue emission (484nm) increases with increasing Dy³⁺ concentration. Moreover, the luminescence intensity firstly increases and then decreases with increasing Dy³⁺ concentration, and reaches the maximum at 3.00mol% Dy³⁺. And the concentration quenching mechanism is the d-d interaction by Dexter theory. The emission intensity of LiCaBO₃∶Dy³⁺ phosphor is enhanced with doping Li⁺, Na⁺ or K⁺. The InGaNbased LiCaBO₃∶Dy³⁺ shows a nice white-emitting, and the CIE chromaticity is (x=0.3001, y=0.3152).

Using ethanol as the precursor of pyrolytic carbon, chemical vapor infiltration of a carbon fiber felt with an initial bulk density of 0.47g/cm³ was performed at the temperature of 1125°C and the pressure of 20kPa, resulting in a bulk density of 1.67g/cm³ after densification of 114h. Extinction angles from 19.5° to 20.5° for various regions in the densified sample are determined, which correspond to a high-textured carbon, leading to flexure strength of 137MPa. Analysis of 2D texture distribution suggests that ethanol is a promising carbon source to synthesize carbon-carbon composites with homogeneously high-textured pyrolytic carbon.

One-dimensional mullite particles were synthesized by sol-gel method from hydrous aluminum chloride (AlCl₃·6H₂O) and tetraethoxysilane (TEOS) as raw materials and WO₃ as catalyst. WO₃ had a desired effect on the anisotropic growth of mullite particles by forming aluminum tungstate (AlWO₄) as growth template at low temperature, which was greatly dependent on the precursor pH. NMR results indicate that the pH during gelation can highly influence the homogeneity of precursor, mullite formation and microstructural features. One-dimensional mullite particles are significant only when the precursor pH is lower than 7. Morphology of the mullite particles synthesized with pH≥7 transforms from anisotropy to isotropy and platelike.