The grain orientation techniques of piezoelectric ceramics have attracted considerable attention because the grain oriented piezoelectric ceramics possess higher piezoelectric properties than polycrystalline ceramics and have the same Curie temperature as polycrystalline ceramics. In this paper, the research progress and trend of grain orientation techniques of piezoelectric ceramics are summarized with emphases on directional solidification technology, multilayer grain growth technique, templated grain growth and reactive templated grain growth technique. The future for the developments of grain orientation techniques of piezoelectric ceramics are also proposed.

By measuring M-T curves, ESR curves, ρ-T curves and MR-T curves of the samples,
the influences of Fe doping (x=0.05, 0.10, 0.20, 0.30, 0.40) upon magnetic
and electric properties of LaMnO₃ were studied. The experimental results indicate that all samples undergo the transition from paramagnetism to ferromagnetism at TC. For the doped samples, there is a paramagnetic-ferromagnetic (PM-FM) transition but there is no insulator-metal(IM) transition. The results are attributed to double exchange interaction between Fe3+ ions and Mn3+ ions and Jahn-Teller effects.

Single-domain Y-Ba-Cu-O(YBCO) high temperature superconductor bulk was fabricated by top-seeding melt texture growth process. The distribution of Y₂BaCuO₅ (Y211) particles and its effect on the critical current density (J_c) and levitation force of the bulk samples were investigated. Scan electron microscope (SEM) analysis showed that the distribution of the Y211 particles presented an inhomogeneous character throughout the YBCO matrix. The experimental result also showed that the critical current density and levitation force were in inverse proportion to the mean radius of the Y211 particles. The smaller the diameter of the Y211 particles and the more uniform the distribution of the Y211 particles were, the larger the value of Jc and the levitation force were. For the sample of single-domain YBCO bulk with 20mm in diameter, the levitation force could reach 33N (77K,0.55T) and the magnitude of Jc could reach 6.6×10⁴A/cm².

Layered perovskite LaSr₂Mn_2-xCu_xO₇ polycrystalline samples were prepared by solid state reaction. Structure and magnetic as well as electric properties were nvestigated
by X-ray diffraction, superconductor quantum interference device and direct current four probe method. The samples have the single phase with layered perovskite structure and the space group is I4/mmm. The substitution of 10％ copper destroys the charge order of LaSr₂Mn₂O₇. Characteristic spin glass state occurs on the LaSr₂Mn_xCu_xO₇, and the spin frozen temperature is near 225K. The electric properties show that the LaSr₂Mn₂O₇ sample’s conduction characters are influenced by the substitution of 10％ Cu, which keeps in the insulator state from 77K to room temperature. At the same time, transport properties are changed by the substitution of 10％ copper. layered perovskite; LaSr₂Mn _2-x Cu_xO₇; magnetic properties; electrical properties

Carbon nanotubes filled with α-Fe nanowires (FCNT) was prepared conveniently by the
pyrolysis of ferrocene. The lengths of iron nanowires were in the range of 30--500nm.
Carbon nanotubes can protect inner iron nanowires from oxidation. After filling FCNT into paraffin wax to form a composite, both the permittivity and permeability in 2-- 18GHz of as-prepared composite samples were measured. Compared with pure carbon
nanotubes (MCNT), the real part, imaginary part of permittivity and the real part of permeability are improved remarkably. However, the imaginary part of permeability is lower than that of MCNT. There are two peaks of reflection loss for FCNT/epoxy coating at 3.5GHz and 5.0GHz, whose reflection loss values are --3.9dB and --4.0dB,
respectively. The results show that this novel absorber is promising to absorb microwave in 2--4GHz frequency effectively.

Uniform P(St-co-AA) microspheres were prepared by microemulsion polymerization. The Fe₃O₄/P(St-co-AA) microspheres with a high magnetic content were prepared by electrostatic self-assembly using P(St-co-AA) microspheres with Fe₃O₄ nanoparticles synthesized by co-precipitation. The effects of pH, stirring on the preparation of Fe₃O₄/P (St-co-AA) were investigated. All samples were characterized by transmission electron microscope (TEM), scanning electron microscope(SEM), X-ray diffraction(XRD), FTIR spectroscope. The magnetic property of the obtained magnetic powder with Fe₃O₄ single phase was tested by VSM. The results indicate that the average sizes of polymer microspheres P(St-co-AA) with carboxyl and the magnetic powders Fe₃O₄ are 70nm and 10nm, respectively. Magnetic property measurement shows that the saturated magnetization of the magnetic powders is 69A·m²·kg^-1 when the applied field is up to 1.5×10⁶/pi(A/m) at room temperature. The assembled Fe₃O₄/ P(St-co-AA) with an average size of 800nm is spherical and the content of magnetic powders is 15.8％.

Core-shell structural SiO₂/Fe₃O₄ nanocomposite particles with adjustable magnetic properties were prepared via a sol-gel process, in which the hydrolysis and condensation of TEOS were conducted on the surface of Fe₃O₄ nanoparticles under the aid of basic catalyst. The effects of the volume ratio of alcohol to water, the concentrations of ammonium and TEOS on the appearances and properties of the nanocomposite particles were investigated. The mechanism of the formation of SiO₂/Fe₃O₄ nanocomposite particles was analyzed. Results show that silica shell is mainly formed from the aggregative growth of silica primary particles on the surface of Fe₃O₄ nanoparticles. With increasing the concentration of TEOS in the range of 0--0.02mol/L, the silica shell thickness increases on the condition of 0.3mol/L of NH₄OH and 4:1 ratio of alcohol to water. Although the saturation magnetization of the nanocomposite particles decreases with the thickness of silica shell increasing, the coercive force of the particles is almost unchanged. And more, the nanocomposite particles remain favorable superparamagnetism.

Zinc oxide nano-hollow spheres were prepared by oxidation of zinc in mercury medium with template of surfactant micelles. SEM, EDX, TG, DTA, XRD and IR were used to characterize the as-grown products. The effect of surfactant on the growth of zinc oxide was discussed. The results show that zinc oxide hollow spheres, amorphous, with nanometer-sized thickness are assembled by zinc oxide nanometer particles. After calcinated, they transform to wurtzite structure. With suitable concentration of PEG or CTAB adding, ZnO hollow spheres can be fabricated on the surface of Zn plate. If no surfactant, excessive concentration of PEG or SDBS is added, ZnO hollow spheres can’t be fabricated.

Polyvinylpyrrolidone(PVP)/vanadyl glycolate (VO(OCH2-CH2O)) core-shell microspheres were assembled by soft-templating method using vanadyl acetylacetone (VO(acac₂) as raw materials. And then vanadium pentoxide (V₂O₅) hollow spheres with particle size from 0.5 to 1μm were obtained by the calcination of composite microspheres. SEM, TEM and XRD were adopted to characterize the spherical morphology, hollow structure and phase composition of the final product, respectively. The mechanism of the formation of V₂O₅ hollow spheres was discussed based on the FTIR of VO(acac)₂, PVP dissolved in EG, VO(acac)2 dissolved in EG, VO(OCH₂-CH₂O)/PVP microspheres and the DTA curve of composite microspheres. Effects of concentration of reagents, the time of reaction on the experiment were studied. The results indicate that the core-shell composite microspheres can be prepared through the precise control of the concentration of PVP and VO(acac)₂, and the microspheres will be formed with ideal shape and surface morphology with reaction time ranging from 75min to 90min.

TiO₂ precursor/pollen grain core-shell composite materials were prepared by hydrothermal synthesis under ultrasound irradiation by using rapeseed pollen grains as template. The core of the pollen grain could be removed by calcination at 550℃ for 6h and the TiO₂ hollow spheres were consequently obtained. SEM, TG, XRD, FTIR and N₂ adsorption were used to characterize the TiO₂/pollen grain core-shell composites and the hollow titania spheres. The results indicate that the ultrasound irradiation helps the dispersion of TiO₂ precursor on the pollen grains’ surface uniformly and the suitable amount of tetrabutyl titanate is 6.6g/g pollen, the proper temperature for the hydrothermal synthesis is 105℃. The final TiO₂ hollow spheres with pure anatase phase, have narrow mesopore-size distribution, with an average pore radius of 1.9nm and BET surface area of 26.76m²·g^-1.

Nano-TiO₂ semiconductors sol (NTSS) was synthesized through a sol-gel method, and its antibacterial abilities were identified by using bacterial pathogens of Pseudomonos syringae pv. lachrymans and Xanthomonas vesicatoria. Taking cucumber plants as experimental objects, the photobiological effects of NTSS on preventing from plant bacterial/fungal diseases and promoting contents of photosynthetic pigments were primarily studied. Results show that crystal species of TiO₂ particles synthesized in experiments are in anatase phase with average size of about 30.6nm. NTSS possesses strong oxidizing power with over 99.9% antibacterial rate by forming continuous and stable antibacterial films on surfaces of substance. Lesion areas, disease incidences and disease indexes of leaves can be significantly reduced by spraying NTSS on cucumber leaves; however, content of chlorophyll and carotenoid in leaves can be significantly promoted. It is proved that NTSS can significantly prevent and control the development and pervasion of bacterial angular leaf spot of cucumber. The experimental results lay an important theoretical foundation and technical approach for developing and applying of biofuntional nanomaterials in agricultural areas.

The nano-TiO₂ powders were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscope (XPS). The results show that nano-TiO₂ is transformed to rutile crystal after treating at 400℃ in N₂ atmosphere and the nano-TiO₂ particles obtained are uniform. Part N atoms are intruded into the TiO₂ crystals and substituted for some of O atoms, which produce oxygen defects. Those oxygen defects become the center of photo activity, which result in the increase of absorbed photons and the formation of broad band gap and make the absorption spectrum move to the visible light. The photocatalytic degradation of methylene blue shows that the visible light catalytic activity of nano-TiO₂ calcined in N₂ atmosphere is improved.

A series of photocatalytically composite materials, CdS/Al-HMS and Pt/CdS/Al-HMS, were prepared by templete reagent, ion exchange, precipitation and impregnation methods. The photocatalysts were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray fluorescence analysis (XRF), UV-Visible diffuse reflectance spectrum
technology. The results show that the structure of the composite material CdS/Al-HMS mainly depends on the amount of CdS in Al-HMS. The doping composite material is formed with low content of CdS and the nanoscale composite material is produced with high content of CdS. The photocatalytic activities of hydrogen productions for coupled materials are carried out by photocatalytic formic acid degradation under visible light irradiation (λ≥420nm). The result indicates that the composite material loaded 6% Pt shows the highest hydrogen generation rate of 22.3mL/h with an apparent quantum yield of 12% at the wavelength of 420nm.

Zr_0.5 Ti_0.5 O₂ mixed oxides were prepared by co-precipitation method. The effects of pH value, precipitation temperature and calcination temperature of Zr_0.5 Ti_0.5O ₂ on its specific surface area, pore size, pore volume and surface acidity were investigated. The samples calcined at 500℃, 550℃, 600℃, 650℃, 700℃, 800℃ for 2h, were characterized by means of BET, X-ray diffraction (XRD) and NH3-temperature programmed desorption (NH₃-TPD). Using the Zr_0.5Ti_0.5O₂ and La-Al₂O₃ as catalyst carriers, and the activities of Pt/Zr_0.5 Ti_0.5O₂ and Pt/La-Al₂O₃ catalysts were evaluated in the simulated gas. The results show that when the pH is 11, precipitation temperature is 25℃, calcination temperature is 550℃, Zr_0.5Ti_0.5O₂ exhibits the highest specific surface area(195m²·^-1), larger pore volume(0.28mL·g ^-1), proper surface acidic amount and acidity. Compared with Pt/La-Al₂O₃, Pt/Zr_0.5Ti_0.5O₂ exhibits excellent low-temperature catalytic activity and lower the light-off temperature of hydrocarbon (234℃) and carbon monoxide (203℃) and nitrogen oxides (213℃). At the same time, it is found that the Pt/Zr_0.5Ti_0.5O₂ catalysts significantly improve the conversion for nitrogen oxides.

Single-phase and ultrafine La_9.33Si₆O₂₆ powders were directly synthesized by a sol-gel self-combustion method using citric acid and ethylene alcohol as chelating reagents and fuels, nitrate as oxidant and ammonia to adjust the pH value of the system. XRD and TEM were employed for the phase identification and morphological observations of the obtained powders, which sintering performance was also studied. The results show that single-phase La_.33Si₆O₂₆ powders with particles sizes ranging from 150nm to 300nm can be directly and rapidly synthesized through sol-gel and self-combustion processes without ary additional thermal solid reactions on the properly selected reaction conditions. The ultrafine powders possess very high sintering activities, and can be well sintered at 200℃ lower than the sintered temperature of the powders derived from conventional solid reactions.

Effects of the main factors which control the slurry rheological behavior and green tape quality of the tape cast SOFC anode support, including ball-milling time, organic solvent type, dispersant addition, plasticizer/binder ratio (R), and defoaming process as well, were systematically investigated. It is found the mixed solvent of ethanol and xylene (1:1 volume ratio) has the optimized wetting capability on the used ceramic powders, improving the suspensibility of powders and the rheology of slurry; the viscosity of the slurry decreases with addition of the dispersant and reaches the minimum at 1.8wt% of dispersant concentration; ball-milling reduces the slurry viscosity which approaches its lower limit after 24h of milling; the slurry viscosity decreases sharply with increase of the R value, and a minimum is obtained at R=1, the rheological behavior of the slurry is significantly improved; deforming agent and vacuum with agitation are effective on air bubble elimination.

CeCl₃, Ce(NO₃)₃ and CeCl₃-KI solutions were respectively electrolyzed at a constant current density in a single chamber cell or a double chamber cell, consequently, CeO₂ powders were produced. After they were calcined at high temperature, the size and structure of ceria were analyzed by means of TEM and XRD. The reasons of size difference of CeO₂ powders prepared in the single chamber cell or the double chamber cell were analyzed. The CeO₂ synthesis mechanisms of electrolizing all the cerium (Ⅲ)-salt solution systems were also discussed in details. The results show that the nanometer scale powders are cubic crystal group in structure and spherical in shape, and the sizes of samples prepared in the single chamber cell are 20-50nm, 30-50nm and 20-100nm, respectively. The size (7-20nm) of CeO₂ powders prepared by electrolizing CeCl₃ solution in the double chamber cell with an anion-exchange membrane is smaller than that prepared in the single chamber cell.

Nano Mg-Al LDHs were prepared by a hydrothermal method in one step. Effects of precursors, alkalinity of the starting solution, temperature and time on phase purity and crystallite sizes of Mg-Al LDHs were systematically investigated. Reaction products were characterized by powder XRD and SEM. Crystallite sizes of Mg-Al LDHs were determined by the X-ray whole powder pattern fitting method. The optimal parameters for preparing Mg-Al LDHs are keeping the ratio of MgO:Al(OH)₃:Na₂CO₃=2:1:1
at 140℃ for 4h to 10h. The formation mechanism proposed for Mg-Al LDHs is dissociationprecipitiationcrystal growth. The reactant type and hydrothermal conditions may influence the dissociation rate of the precursors, nucleation and growth rates of Mg-Al LDHs, as well as phase combination and crystallite sizes of the reaction products.

A series of samples of AlN-BN ceramic composites with different contents of sintering additives　CaF₂(0-4wt%) were prepared by hot-pressing in nitrogen atmosphere at 1850℃ for 3h. The effects of sintering additives on densification, dielectric properties and thermal conductivity of AlN-BN composites were explored. The addition of CaF₂ results in improvements in the level of densification and purified the grain boundary. AlN-BN composites with relative density of 98.53%-98.54% are obtained when CaF2 contents are 3wt%-4wt%. Dielectric constants of samples are between 7.29 and 7.60 and the best tanδ value is 6.28×10^-4. It is found that dielectric constants increase with the increasing CaF₂ contents and depend on the density of
the AlN-BN ceramic composites. The highest thermal conductivity reach 110W·m^-1·K^-1 by adding 3wt% CaF₂.

High-density aluminum nitride ceramics were fabricated without sintering additives under high pressure (3.1-5.0GPa) and different temperature (1300-1800℃) in China-type cubic anvil high-pressure and high-temperature apparatus, using AlN powder produced by SHS method as starting material. The effects of sintering conditions, i.e. time, temperature and pressure, on sintering characteristics of AlN ceramics were studied. The sintered bodies were characterized by XRD and SEM. The results show that high pressure sintering can lower the sintering temperature and shorten the sintering time. The microstructure of the sintered bodies is homogeneous. The relative density of AlN ceramics sintered at 5.0GPa and 1300℃ for 50min is 94.92%. The lattice parameters of the specimens sintered at 5.0GPa and 1700℃ for 125min are decreased by about 0.09% than that of the AlN powder.

A new type of porous silicon carbide was fabricated by filter paper-phenolic resin composite through mold-stacking, drying, carbonization and Si infiltration process. When the carbonization temperature is fixed, with the increase of the content of phenolic resin, the open porosity of porous carbon decreases, and the bending strength of porous carbon increases. When the weight ratio of phenolic resin and filter paper is fixed, with the increase of carbonization temperature, the open porosity of porous carbon decreases, and the bending strength of porous carbon increases . SEM observation reveals that the irregular interconnected pores are derived from the disorder arrangement of filter paper microfibers and the different shrinkage ratios between phenolic resin and filter paper during carbonization. Moreover, these pores remain to form SiC. Open porosity of porous silicon carbide increases, and bending strength and fracture toughness decrease with the increase of Si removing time. When the samples are heated up to 1650℃ with 30min Si removing, the excess Si in bigger pores is removed, the resulting porous SiC has higher bending strength and fracture toughness.

The convection heat transfer coefficient on A1₂O₃ coating during microarc oxidation process was estimated by experiment and
simulation. The Al₂O₃/Al interface was found to be a heat-transfer passage. During quenching, most heat of the micro-melting-pool was transferred through the Al substrate and the A1₂O₃ coating nearby. The micro-melting-pool was modeled by the finite element method (FEM), and the process of quenching was characterized by the simulated temperature-time curves of the nodes along the depth, respectively. The effects of the quenching on the distribution of α-A1₂O₃ and surface morphology of A1₂O₃ coating were discussed by comparing the relative cooling rate at different positions. The influence of pressure on the microstructure of Al₂O₃ coating was also discussed briefly.

Alumina nanorods were successfully prepared from the thermal decomposition of Al(OH)₃·xH₂O nano precursors obtained hydrothermally at 120℃ for 10--17d, by using Al(OH)₃ and LiOH as raw materials. The as-prepared samples were characterized by TEM, HRTEM, SAED and XRD. Besides, the thermal behavior of decomposing Al(OH)₃·xH₂O precursors synthesized by hydrothermal process was studied through TGA. The results show that the as-prepared Al₂O₃ nanorods have rod-like morphology and single crystalline nature. The mechanism for the Al₂O₃ nanorods growth is agreed to Ostwald ripening and oriented attachment. Lye plays an important role in synthesizing the Al₂O₃ nanorods. As 5mol/L KOH lye displaces original LiOH, the
as-prepared nanowires in the reaction have smaller morphology, with a diameter of 2nm and a length of 10--25nm.

The composite Yb:Y₃Al₅O₁₂/Y₃Al₅O₁₂ crystal was made by thermal bonding method. Structure and bonding quality of composite crystal were characterized in detail. The cross section of the composite crystal was observed by optical microscope and scanning electron microscope (SEM), the stress in bonding area was observed by micropolariscope; optical homogeneity of the composite crystal was characterizated by interference fringe; bonding quality of the composite crystal was also studied by infrared transmission spectra. All experiments show that the composite Yb:YAG/YAG crystal has no interface defects, and no space transition layer in bonding area. The composite crystal has good optical
homogeneity.

Well dispersed yttrium aluminum garnet (YAG) nanopowders with mean particle size of about 50nm synthesized by modified co-precipitation method were used to sinter YAG transparent ceramics with 0.5wt% TEOS as sintering additive by two step sintering process. The samples were first heated to a higher temperature ranging from 1700℃ to 1800℃, then cooled down to a lower temperature ranging from 1500℃ to 1600℃, and held at the lower temperature for 10h. Grain-boundary migration is suppressed and grain-boundary diffusion is promoted during the two step sintering process. When the two step sintering temperatures are 1800℃ and 1550℃, the microstructure of YAG is homogeneous with average grain size of 6μm without abnormal grain growth and the transmittance of the specimen is 72.0%

Porous composite scaffolds of nano-hydroxyapatite/chitosan/carboxymethyl cellulose (n-HA/CS-CMC) with different weight ratios (0/50/50, 20/40/40, 40/30/30 and 70/15/15, respectively) were prepared by freeze-drying method for bone tissue engineering scaffold. The mechanism of formation of the composite scaffolds and the effects of inorganic component (n-HA) on the porous morphologies, mechanical properties and their degradation rate of n-HA/CS-CMC composite scaffolds were investigated by means of IR, XRD, SEM, TEM, universal material test machine and PBS soaking. The results show that the composite scaffolds is mainly formed through the complexation reaction between the two opposite polyions of CS and CMC, then n-HA is firmly incorporated into the polyelectrolyte matrix of CS-CMC without agglomeration. The addition of inorganic component n-HA into the system of CS-CMC, which decreases slightly the regularity of pores and porosities of the n-HA/CS-CMC composite scaffolds. However, the addition of inorganic component n-HA increases the compressive strength and steps down the in ~vitro degradation of the composite scaffolds. The composite scaffold with weight ratio of inorganic component (n-HA) of 40% is most suitable for bone tissue engineering scaffold in view of its highly interconnected porous structure, high compressive strength and the acceptable degradation rate.

Microarc oxidation (MAO) technique was applied for the formation of ceramic coating on titanium surfaces, and the modulating mechanism of sodium polyacrylate to crystal growth was studied by SEM, XRD and FT-IR in the biomineralization. Results show that the crystal size of HCA is reduced when specimen is bio-mineralized with the addition of sodium polyacrylate. Meanwhile, the morphology of crystal is changed and the density of mineralization layer is increased when sodium polyacrylate is applied.

Nano-hydroxyapatite (n-HA) was modified by using silane coupling reagent (KH-560), and the interfacial interactions between n-HA and KH-560 was also studied. Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectra (XPS) analyses show that the silane coupling molecular binds strongly to n-HA surface. Chemical bonding (Si--O--P) is formed by the reaction between Si--OH and HPO ^2-₄ group, and a similar interface effect exists between Si--OH and the hydroxyl group of HA. Surface modification of HA particles can improve the mechanical strength of the n-HA/polycarbonate (n-HA/PC) composites dramatically. SEM observation shows that modified HA particles uniformly distribute in the PC matrix. The results indicate that the interfacial interaction between surface-modified inorganic particles and polymer matrix is crucial for the improvement of the mechanical strength of the composites.

CaB₆ powder was prepared by combustion synthesis with CaO, B₂O₃ and Mg as reactants. The DTA curves of the different reaction systems were investigated. Combustion products and leached products were characterized by XRD, SEM and particle size distribution techniques. The results indicate that apparent activation energy(E) of the exothermic peak near 872℃ for reaction Mg+3B₂O₃+CaO=CaB₆+10MgO is 15.71kJ·mol^-1 and its reaction order(n) is 1.1. The apparent activation energy is lower, so the reaction occurs easily. Combustion products consist of MgO, CaB₆ and a little amount of Mg₃B₂O₆ and Ca₃B₂O₆, and no nitrides form during the combustion process in air. CaB₆ powder purity is 92.5% after combustion products are leached with
acid. CaB₆ particles become finer with the increasing of the preparing sample pressure.

The dissolution process of 40ZnO-10MgO-50P₂O₅ glass in acid medium was studied by weight loss analysis. The result shows that the water dissolution rate of phosphate glasses doped with bivalent ions is low. However, situation changes greatly as the pH value of the solution reduces because of the ion exchange reaction between R ²⁺ in glass and H⁺ in acid. The stability of glass network is thus destroyed and followed by hydrolysis reaction of phosphate structural group. The dissolution rate increases exponentially with the increase of temperature and the reaction activation energy decreases with the increase of pH value. The dissolution rate reaches the maximun in concentrated HCl due to the contribution of both H⁺ and H₂O. The mechanism of the dissolution process is proposed into two steps: first, the weight loss is proportional to the square root of the time, and the next, it is proportional to time, which indicates the formation and development of hydrate layer on the glass surface.

BaO-Al₂O₃-SiO₂ (BAS) glass-ceramics with stoichiometric and off-stoichiometric celsian composition were fabricated, doped with B₂O₃ for melting and sintering. Crystallization and phase transformation characters of two groups of BAS glass-ceramics with and without ZrO₂ were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and dilatometry. Results show that for both BAS glasses, the sintering temperature is lower than 850℃ and crystallization peak temperature is lower than 900℃. The crystallization characteristic of hexacelsian in each sample is bulk nucleation and three-dimensional growth because Avrami exponent is 2.8--3.9. The crystallization characteristic of monocelsian in the sample doped with ZrO₂ is surface nucleation and one-dimensional growth because Avrami exponent is 0.95, while it is bulk nucleation and three-dimensional growth because Avrami exponent is about 3.0 in the sample without nucleation agent. It reveals that crystallization peak temperature and activation energy get lower in stoichiometric BAS glass-ceramics doped with ZrO₂, while the crystallization peak temperature get higher in off-stoichiometric BAS glass-ceramics doped with ZrO₂. Stoichiometric BAS glass-ceramics doped with ZrO₂ crystallized at 850℃ for 12h is completely transformed into monocelsian. Monocelsian will not be detected in off-stoichiometric BAS doped with ZrO₂ crystallized at 850℃ for 100h.

Influences of acid leaching and thermal oxidation on aqueous dispersibility were investigated for four types of commercial silicon nitride powders, in conjunction with their DRIFT spectra and soluble counter-ions. Three of the powders, referred to FD1, FD2 and M11, were produced by the direct nitridation of silicon powder with different pulverization processes, while the UBE powder was made by calcination of the silicon diimide precipitate. Particle surface groups and soluble counter-ions (especially high-valency counter-ions) are proved to be the crucial factors that determine the aqueous dispersibility of Si3N4 powders. The study indicates that the high-valency counter-ions are the crucial factor limiting the dispersibility of powder FD1, which can be eliminated by acid leaching. For powder FD2, the barrier to preparing highly concentrated suspension is the large number of hydrophobic Si-O-C-R groups on particle surfaces, and those groups can be removed by thermal oxidation. For powder M11, the high concentration of soluble NH⁴⁺ restricts the aqueous dispersibility of the as-received sample, which can be removed by thermal oxidation. For the as-received powder UBE, however, hydrophobic Si-O-Si surface groups limit the preparation of highly concentrated slurries. After particle surface modification, the four types of silicon nitride powders show excellent aqueous dispersibilities.

Mesoporous Fe-MCM-41 materials were synthesized by using ionic liquid 1-cethyl-3-methylimidazolium bromide [C₁₆mim]⁺Br^-) as template at room temperature and characterized by X-ray diffraction, N₂ adsorption-desorption, FT-IR, EPR, UV-Vis. Results show that these mesoporous materials possess high surface area. The pore size distributions of Fe-MCM-41 show that there are two types mesoporous. Part of iron atom still retain in the framework after removal of the template by calcination except those transferring to the wall surface. Fe species on wall surface are of high dispersion. This indicates that stable framework-iron containing mesoporous molecular sieves Fe-MCM-41 can be successfully synthesized.

The texture and nanostructure of C/C composites infiltrated by improved ICVI procesc was investigated by polarized light microscopy and high spatial resolution transmission electron microscope, respectively. Results show that there are three layers of pyrocarbon with different texture around the fiber. They are smooth laminar, rough laminar and dark laminar pyrocarbon from fiber to exterior, respectively. The interface bonding between the matrix and the fiber as well as that among different texture are well combined. The microcracks generate and propagate in rough laminar pyrocarbon. They do not straight extend through the interface into the lower texture, but propagate by bridged-link through the interface into the lower texture. The preferential orientation of the crystal lattice for the different texture pyrocarbon is quite different in short ranges and long ranges.

A set of boron doped tetrahedral amorphous carbon (ta-C:B) films were prepared in a filtered cathodic vacuum arc system using boron mixed graphite as targets with weight percentage ranging from 0 to 15%. The chemical bonding states of ta-C:B were studied by X-ray photoelectron spectroscope. The result shows that B is mainly threefold coordinated and the fraction of sp³ hybridized carbon decreases in magnitude with increasing boron content. Raman analysis also shows that the introduction of B in the ta-C:B films facilitates the clustering of sp² carbon sites which reduces the bonding distortion and intrinsic stress of the films.

ZnS electroluminescent phosphors were prepared by high temperature (1100℃) solid state reaction, subsequently milling for some time (t=0-180min) and the final low temperature annealing process (750℃). The as-synthesized phosphors were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, scanning electron microscope and photoluminescence spectra. Electroluminescence performance was investigated on the screen-printing electroluminescent lamp at 100V and 400Hz. Increased milling time leads to intensity reductions and width increases of some diffraction peaks, and results in slight red-shifts of the absorption edges. Photoluminescence brightness declines about 58% after milling for 180 min while electroluminescence brightness increases from 14.39cd/m²(t=0min) to the peak value 90.13cd/m²(t=160min). The changes of photoluminescence and electroluminescence performances originate from the defects in the microstructure induced by milling.

The cation distribution in Zn(Ga,Fe)₂O₄ solid solutions with spinel structure were calculated by using the X-ray powder diffraction density method (R factor Method). The results indicate that the cations show osculant but lean to inverse distribution in Zn(Ga,Fe)₂O₄. With Fe³⁺ introduction into the spinel structure of Zn(Ga,Fe)₂O₄, the Zn²⁺ concentration in A sites and Ga³⁺ concentration in B sites increase. Meanwhile, the IR spectra of samples indicate threshold frequency representing the activation energy for electron conduction is affected sharply by the substitution of Fe³⁺ for Ga^3+.

CdZnTe crystal was grown with different In dopant concentration in excess Te atmosphere. The relation between In dopant concentration and resistivity, carrier concentration, mobility of the CdZnTe crystal was investigated. In addition, In-doped compensation mechanism in CdZnTe crystal was also discussed. Results show that the high resistivity of CdZnTe crystal obtained is 1.89×10¹⁰Ω· cm when the In dopant concentration is at the level of 5×10¹⁷cm^-3.

The X-ray diffraction (XRD) tests showed that the diffraction lines of hk0, h-k=3n in the hexagonal closed packing structured (HCPS) ZnO appeared only crystallite broadening effect. The two-fold broadening effects of crystallite-fault could be observed in the diffraction lines of h-k=3n±1, yet the selective broadening was not obvious. In this study, the least square method for separating twofold broadening effect of crystallite-fault were proposed and used to characterize the average crystallite size and stacking faults probability of HCPS ZnO. The results show that the average crystallite size and stacking faults probability are related with the preparation methods and the stoichiometric ratio of ZnO.

The uniform and high intensity reticulated ceramics were fabricated with α-Al₂O₃ slurry by gel casting injection. The influences of solids volume fractions, dispersant and pH values on the rheological behavior of α-Al₂O₃ reticulated ceramics were studied. Results show that when pH=9, dispersant=0.5wt%, solid volume fraction=57%, the slurry has a good fluidity, and its viscosity is 140mPa·s. By adopting the argon plasma treating process and the stem grafting of acrylic acid, the absorbed slurry values of the foaming plastics will be changed from 0.42g/cm³ to 0.71g/cm³. The reticulated ceramics fabricated have apparent porosity of 86%, volume density of 0.52g/cm³, and compressive strength of 3.60MPa.