The first-principles calculations were widely used in many different fields of materials science. Most of the calculations were based on the density functional theory. Starting from the density functional theory (DFT), we first summarized the theory of first-principles calculations in detail, then we introduced how to get the piezoelectric constants, dielectric constants etc by using the density functional perturbation theory (DFPT) and the Berry-phase theory. We summarized the recent literatures about the first-principles calculations of piezoelectric properties. In the end we summed up the problem existed nowadays and foresaw the future.

Gd^3+_-doped Mn-Zn ferrite nanoparticles were prepared by a chemical co-precipitation method. The effect of Gd³⁺ contents on structure, magnetic properties and heat effect under AC magnetic field was also investigated. The results show that Gd³⁺ can enhance the magnetic properties and heat effect of Mn-Zn ferrites with the proper doped amount. Among the samples prepared, Mn_0.4Zn_0.6Gd_0.06Fe_1.94O₄particles with the size of 20nm possess the maximal magnetization M_s and coercive force H_c. The temperature rise of the suspension of 50g sample and 1mL water can reach up to 31℃ under a 60kHz magnetic field, showing the sufficient heating ability for hyperthermia therapies. The results support the concept that the Gd³⁺-doped Mn-Zn ferrite nanoparticles may serve as new thermal seeds for magnetic hyperthermia.

Core-shell TiO₂/SiO₂ nanoparticles were synthesized successfully by H₂/Air flame combustions, and the formation mechanism of core-shell nanoparticles was analyzed. The structures and properties of these TiO₂/SiO₂ particles were investigated by using TEM, HRTEM, XRD and FTIR. The transformation from anatase to rutile and the grain growth are hindered due to the addition of silica into matrix. Both the chemical reaction rate and the nucleation rate of TiO₂ particles are much faster than those of SiO₂. The formation of primary TiO₂ particles is faster than that of SiO₂ in the third jet due to the low temperature and nuclear rate. Heterogeneous nucleaton of SiO₂ on the surface of TiO₂ is the main reason of core-shell nanocomposites formation.

Lead selenide nanoclusters and nanocubes were successfully in situ prepared through a room-temperature biosubstrate-induced approach employing the Pb(Ac)2 solution, Na₂SeSO₃ solution as the reactants, and the eggshell membrane (ESM), which contains many unique and periodically distributed functional groups, as the live biomaterial. Results show that under the complexation and electronic roles of these macromolecules with inorganic precursor ions, PbSe nanocrystallites firstly process oriented-formation, controlled-congregation and periodic-distribution on the mantle of ESM fibers, then they are self-assembled into the uniform nanoclusters with well crystalline, which are orderly distributed on the surface of ESM. The results of UV-Vis and PL analysis also indicate PbSe nanoparticles prepared are with fine, uniform size and nice distribution.

Herein, Fe₂O₃ nanostructures were prepared by the ethylene glycol (EG) assisted hydrothermal process. The effects of the molar ratio of Fe ³⁺ and OH^-, the amount of EG, the concentration and subsequent annealing on the morphology and composition were investigated. Moreover, the effects of Fe₂O₃ nanostructures with different morphology and size on the magnetic properties were also investigated. The results indicate that only hexagonal -Fe₂O₃ nanoparticles can be obtained when the molar ratio of Fe ³⁺ and OH^-is less than 1:4 with or without the addition of EG; when the Fe ³⁺ and OH^- is more than 1:4, the orthorhombic airplane-like FeOOH nanostructures can be achieved with the assistance of EG; while the Fe ³⁺ and OH^-is more than 1:4, the orthorhombic FeOOH nanorods can be achieved without the assistance of EG. The airplane-like FeOOH nanostructures and FeOOH nanorods are transformed into the porous airplane-like Fe₂O₃ nanostructures
and Fe₂O₃ nanorods. With the increase of the concentration, only the size of the nanostructure is enlarged and the morphology of the nanostructure is unchanged. The different size and morphology have great influence on the magnetic properties of the Fe₂O_3.

Nano-ZnO was synthesized by an improved direct precipitation method, followed characterization by both of XRD and TEM. It demonstrates that the diameter of nano particles is 10nm calculated with Scherrer formulate and observed with the photo of TEM. The nano particles were modified with oleic acid, span-60 and sodium laurate, respectively. Macroscopically, the stability of the nano particles was analyzed by the subsidence experiment and discussed the stability of the modified nano-ZnO by the three surfactants. The effect of modification with oleic acid is excellent and the others can not exist in liquid paraffin stably. Microcosmically, the FT-IR spectra indicate that nano particles combine with oleic acid by both types of covalent bond and hydrogen bond to form a singlemolecule layer, but the modification with span-60 and sodium laurate is not stable.

Hydrous zirconia was prepared at low pH values with ZrOCl₂·8H₂O as raw material, H₂O₂ as hydrolysis promoter and ethanol as solvent. FT-IR, TG and XRD were applied to study the components, structure and heat-stabilization of hydrous zirconia. Light microscope and FESEM were used to analyze the microcosmic structure of hydrous zirconia, its formation mechanism was also discussed. The results show that the molecular formula of hydrous zirconia is Zr(μ-OH)₂(OH)₂·2H₂O. The hydrous zirconia is amorphous, and as the treating temperature rising, it will turn from metastable tetragonal phase to monoclinic phase. The hydrous zirconia is fiber cluster composed of small short fibers via hydrogen bonds.

New organic-inorganic nanocomposite materials of collagen and modified TiO₂ were prepared. The change of content of collagen in the nanocomposites along with the alteration of temperature and pH value was studied, and the influence of such factors as types of TiO₂ crystals, Al₂O₃ films of modification on TiO₂ and cross-link with glutaraldehyde on the infrared emissivity of the composites was investigated. The results indicate that the optimal temperature and pH value for the reaction between collagen and modified nanosized TiO₂are 50℃ and 8.0 respectively, under which the content of collagen increases up to 9.45wt%. The nanocomposites are endowed with much lower infrared emissivity and the thermal stability of the nanocomposite materials is enhanced greatly due to the strong interactions between collagen and modified nanosized TiO₂. After being cross-linked by glutaraldehyde, disorderly distributional nanocomposites are turned to regular and ordered laminar netty ones, which improves the tensility and stability of the materials and lowers the infrared emissivity further to 0.502.

Alumina nanowires, amorphous, with diameters from 5 to 15nm, were prepared by catalytic oxidation with mercury as medium. FE-SEM, TEM, EDX, XRD, IR were used to characterize alumina nanowires. With elevation of temperature, oxygen content and purity of aluminium, the alumina nanowires’ specific surface area increases. The concentration of HgCl2 solution and the immersing time of aluminium have no apparent influence on alumina nanowires’ specific surface area.

Potassium titanate nanofibers ( K_1.34H_0.66Ti₂O₄(OH)₂) were prepared by using ion-exchange reaction between KOH solution and titanic acid nanotube (H₂Ti₂O₄(OH)₂). TEM and XRD results show that the nanotubes change into nanofibers and the crystalline structure alters. K/Ti atomic ratio, chemical state of K and Ti elements for the product were determined by means of atomic absorption spectrophotometry, colorimetric method, and X-ray photoelectron spectroscopy. The results indicate that the empirical formula of the product is K_1.34H_0.66Ti₂O₄(OH)₂. Compared with H₂Ti₂O₄(OH)₂ nanotubes, the thermal-stability of potassium titanate nanofibers is higher. At T>700℃, the crystalline structure of this material changes into monoclinic phase K₂Ti₄O₉. High temperature treatment results in nanofibers’ sizes increasing, but the aspect ratio is still high. The BET surface area of the material is 104m ²·g^-1.

A series of single-crystalline La _1-x Ca _x MnO ₃ nanowires were successfully prepared by a hydrothermal method. X-ray diffraction (XRD) results demonstrate that theLa _1-x Ca _x MnO ₃ nanowires have orthorhombic perovskite structure without any impurity phases. Transmission electron microscope (TEM) images clearly show that the as-synthesized samples are made up of large quantities of single crystal nanowires with lengths ranging from several to several tens of micrometers and uniform diameter (about 90nm). The high-resolution transmission electron microscope(HRTEM)investigations of La _0.5 Ca _0.5 MnO ₃ nanowires indicate that the nanowires have very clean surfaces without any defects and grow along <100> direction. The result of magnetic measurement indicates that the La _0.5 Ca _0.5 MnO₃ nanowires have an enhanced Tc due to the shrinkage of unit cell volume and shape anisotropy.

The hydrothermal synthesis of sodium niobate (NaNbO₃) powders with orthorhombic structure using Nb₂O₅ and NaOH as raw materials, KOH as mineralizer, was investigated. The powders were identified by X-ray powder diffraction (XRD) and the Fourier transform infrared (FTIR). The microstructural evolution and the particle size of the samples were examined by scanning electron microscope (SEM), and the main chemical compositions of the powders were studied by EPMA. It is found that there is super-structure existing in NaNbO₃ powders by TEM and EDS analysis. The experimental results show that the alkaline concentration and reaction time have influences on the crystal structure and morphology of the resultant powders.

Quasi-monodispersed spherical titania particles with variable sizes were prepared by the sol-gel synthesis with the addition of surfactant. The particles were characterized by the scanning electron microscope, transmission electron microscope, X-ray diffraction and nitrogen absorption. The influence of surfactant of ODA, Span-80, F-127 and PEG with various molecular weight on the morphology, the size, and the size distribution of particles was investigated respectively.The research results show that the steric hindrance of surfactant is very important to morphology, size and size distribution of titania particles. Perfect spherical particles can be obtained when the steric hindrance of surfactant is big enough. Nitrogen absorption measurements reveal that titania particles synthesized by addition of F-127 or PEG-20000 possess meso-pore structure, and the pore diameter is about 3.4nm and 2.6nm, respectively.

The spherical UO₂ ceramic particles were prepared by a sol-gel method with U₃O₈ powders as raw material, which combines advantages of external gelation and internal gelation methods. The process includes steps of sol preparation, gel particles forming, aging, ashing, drying, calcining, reducing, sintering, sieving and separating. The crystal form of the ceramic particle is face-centered cubic, and its density reaches 98.18% of the theoretical density value. All of the O/U ratio, diameter, sphericity and odd-shaped particles fraction can reach the design specification. Influences of many factors are also analyzed.

Mechanical-activation-assisted combustion synthesis of SiC was conducted with PVC and/or NH4Cl as promoters. The mechanical activation of the Si-C reactants through high-energy attrition milling results in substantial decrease of the ignition temperature and the incubation time for the Si-C combustion reaction. Ultra-fine β-SiC powders with equiaxed grains can be synthesized at the preheating temperature as low as 1050C. The specific surface area (SSA) of the combustion synthesized SiC powders is 4.36m²/g, and the average particle size is less than 5μm.

potassium nitrate and potassium chloride were chosen as additives. KDP crystals were grown from the aqueous solution by the traditional temperature-lowering method and a “point seed” rapid method. Scatter particles are an important parameter to evaluate the properties of KDP crystals. Light scatter was detected with an ultramicroscopic method. The effects of SO₄^2- , NO₃^- and Cl^- ions on light scatter in the crystals were studied. Results show that SO₄^2- ions have a little effect on the light scatter of KDP crystals and the scatter particles are in a low density. With the increase of the dopant concentration, the density of scatter particles increases a little. For KDP crystals grown by the traditional temperature-lowering method, the existence of NO₃^- and Cl^- ions aggravates the light scatter in KDP crystals severely. The effect on the light scatter of KDP crystals grown by “point seed” rapid method is not evident.

A new piezoelectric crystal Sr₃Ga₂Ge₄O₁₄(SGG) has potential applications in Surface Acoustic Wave (SAW) device. Based on the piezoelectric properties recently reported, the SAW properties of SGG crystal in some cuts were calculated by means of Christofel Equation and boundary conditions for the first time. Compared with the well-known piezocrystal La₃Ga₅O₁₄(LGS), SGG crystal shows higher electromechanical properties.

Oxyhalide tellurite glasses: (80-x)TeO₂-15ZnCl₂-xBaO-5NaF(x=30,20,10,0mol%) were prepared. The mechanical strength performance, thermal properties, Raman spectra, UV absorption spectra and Infrared transmission spectra of the samples were investigated. The effects of composition content change on the structure and infrared transmission properties of glasses were investigated by means of Raman scattering. The results show that the transmission in mid-infrared region significantly increases and the IR cut-off shifts towards longer wavelength with increasing BaO, the mechanism was also discussed. The addition of halide to the glasses and the treatment with pure O₂ during melting are useful for the decrease of OH^-1 absorption bands, meanwhile the infrared transmittance is increased. The presented oxyhalide tellurite glass is a kind of optical material with high infrared transmission. It exhibits a high transmittance (≥80%) in the mid-infrared regions and possesses an infrared cut-off edge up to 6.5μm.

LiFePO₄/C composite cathode materials were synthesized by a novel carbothermal reduction(CTR) method using glucose as carbon resource. The precursors and the products were characterized by TG-DTA, XRD, TEM, and the reaction mechanism was investigated. The electrochemical performance of the samples was measured. The results show that the new method can reduce synthesis temperature, and the sample prepared at 600℃ for 24h can deliver a discharge capacity of 156mAh·g^-1 at 0.05C. The first discharge capacities of LiFePO4 at 0.1C, 0.2C, 1C are 146mAh·g^-1, 135mAh·g^-1, 130mAh·g^-1, 121mAh·g^-1, respectively. It retains discharge capacity of 119mAh·g^-1 at 1C after 30 cycles, with only 1.56% capacity decrease.

TaC was deposited by a chemical vapor infiltration(CVI) method with TaCl₅-Ar-C₃H₆ system in the carbon fiber felt. The influences of temperature on CVI deposition rate, deposition uniformity, phase composition, crystallization size and surface growth morphology of TaC coating in carbon fiber felt were studied. The experimental results show that, the deposition rate increases firstly with the rising of temperature, reaches its maximum value at 950℃ and then decreases; at 900℃, the deposition uniformity is the best; the highly crystalline TaC can be deposited between 800℃ and 1000℃ and the crystalline size increases at elevated temperature; it is island-like growth model of TaC on the carbon fiber between 800℃ and 1000℃; with the rising of deposition temperature, the sizes of the deposition islands increase firstly and then decrease; the diffusion ability of the deposition islands increases, and the deposition islands link and melt each other at elevated temperature.

The ceramic marerial of barium titanate (BT) was synthesized by a sol-gel method. The mircrostructure and morphology of the powders were characterized by IR, XRD and TEM. The dielectric constant and permeability of the mixture of BT powders and paraffin wax were measured. The microwave absorbing performance of BT powder and epoxide (EP) resin composite was studied in the frequency range of 8--18GHz. The results show that the BT powder exists in the form of tetragonal phase with the size in the range of 30--40nm. The BT/EP composite exhibits good microwave absorbing performance in the frequency range of 8--18GHz, when the content of BaTiO₃ is 20vol%, the performance is the best. The microwave absorption mechanism of BaTiO₃ powders is mainly due to the dielectric relaxation. The BT powder will be a good candidate for microwave absorbing materials.

The two dimensional carbon fiber reinforced silicon carbide matrix (C/SiC) composites were prepared by a chemical vapor infiltration method. Based on the coupling stress equivalent simulation system, a characterization method with the change of torque was proposed to evaluate the friction behavior under transmitting motion. The friction and wear behavior and wear mechanism of C/SiC composites under high load and low rotation velocity based on transmitting motion were studied. Results show that a good wear resistance and load-carrying ability is demonstrated by the low friction torque, low wear rate and small material deformation under high loads. Under the same testing condition, the wear rate of C/SiC composites is only 1/10 - 1/20 of that of Ti alloy. The wear behavior on contact surface is mainly grain-abrasion mechanism under low rotation velocity, and no hot cracking is caused by the high loads during tests.

A novel method of temperature-pulsing chemical vapor infiltration (T-pulsing CVI)was introduced. And interfacial coatings of silicon carbide (SiC) layer and pyrolytic carbon (PyC) layer were processed via the route. 3D carbon fiber preforms were densified by forced-flow thermal-gradient chemical vapor infiltration (FCVI) with the precursor of hexamethyldisilazane (HMDS). The microstructure of interphases was investigated by transmission electron microscope (TEM). The configuration of specimens' fracture surface was observed by scanning electron microscope (SEM). Results show that the density of the composites is 1.98g·cm^-3. The thickness of the SiC layer estimated is 20nm, and 50nm for the PyC layer. The average flexural strength of the composites is 458MPa at room temperature, and the average fracture toughness is 19.8MPa·m^1/2.

To understand the strain rate sensitivity of compressive strength of carbon clothe/carbon (C/C) composites, quasi-static and dynamic compressive experiments were conducted in its x-y plane by means of electric universal test machine and Split Hopkinson Pressure Bar with pulse shapers. The experimental results show that the dynamic compressive fail strength of C/C composites has strong stain rate sensitivity and it increases with strain rate. Compared with the quasi-static compression, the dynamic compressive strength is higher by 70% or so. Meanwhile, the samples are failed by shearing under quasi-static loading, and by crushing under dynamic loading. The different mechanical behaviors from the experimental results indicate that it may be related to the strain rate sensitivity of interfaces characteristic of C/C composites and the change of the failure modes.

Li_1.0Nb_0.6Ti_0.5O₃ (LNT) ceramics were prepared at 900℃ by adding B₂O₃-ZnO-La₂O₃ (BLZ) glass as sintering agent, and the densification process and the microwave dielectric properties of the material were investigated. The results show that the BLZ glass can effectively decrease the sintering temperature of the material. Beside the main crystal phase Li_1.0Nb_0.6Ti_0.5O₃, LaNbTiO₆ is found in the material, which is believed to be the product of the reaction between LNT and BZL glass during sintering. Adding BZL glass to LNT ceramics leads to the decrease of dielectric constant k and the quality factor Q×f of the material, but at the same time, helps to improve the temperature coefficient of resonant frequency τf. The low firing Li1.0Nb0.6Ti0.5O3 ceramic is possessed with k≈8, Q×f≈4800GHz and τ_f≈11×10-6/℃.

The composites with the nominal composition of (1-x)La_2/3Ca _1/3 MnO ₃/xSb₂O ₅ were fabricated. The study of temperature dependence of resistivity at zero field shows that the metal-insulator transition temperature (T _p) and the resistivity of the composites are dependent on Sb₂O₅ addition level x. When x<3%, T _p shifts towards low temperature and resistivity increases with the increase of x. But T _p shifts towards high temperature and resistivity decreases with further increasing of x. The measurement for temperature dependence of magnetoresistance (MR) indicates that MR effect can be largely enhanced in the composites with small Sb₂O₅ addition.

Lead-free (1-x)(1-x)(K_0.5Na_0.5)NbO₃- xLiNbO₃ piezoelectric ceramics were prepared by a traditional ceramic processing. The sintering characteristic, the microstructure and electrical properties of (1-x)(K_0.5Na_0.5)NbO₃- LiNbO₃
ceramics were investigated. Results show that all specimens exhibit a pure perovskite structure and the phase structure at room temperature transforms from orthorhombic to tetragonal with the increase of LiNbO3.The microstructure of (1-x)(K_0.5Na_0.5)NbO₃- LiNbO₃ ceramics exhibits apparent difference due to different amounts of LiNbO₃. The sinterability of (1-x)(K_0.5Na_0.5)NbO₃- LiNbO₃ is improved and the sintering temperature is lower than that of pure KNN ceramics. The (1-x)(K_0.5Na_0.5)NbO₃- xLiNbO₃(x=0.06) ceramics exhibits an excellent piezoelectric properties with the piezoelectric constant d₃₃, the electromechanical coupling coefficients k_p and k_t of 205pC/N, 40.3% and 49.8%, respectively.

The damage threshold and ablation area for MgAl₂O₄ transparent ceramic (MATC) by a femtosecond laser pulse at a wavelength of 800nm were studied. The ablated spots were examined by means of a charge coupled device (CCD) camera and a scanning electron microscope (SEM). The IR transmission properties of MATC machined by femtosecond laser pulses were measured by a micro-IR spectrum device. The result shows that the damaged area exhibits a linear dependence with the increase of pulse energies under the condition of a single pulse, and the area is Boltzmann distribution with the increase of the pulse number under the condition of multipule pulses. The ablated spot under optimized energy pulses (near the damage threshold energy) can improve the IR transmission from 82% to 86% in the band of 2500-7000cm^-1 for MATC. When the pulse energy exceeds the threshold energy, the transmission of MATC decreases rapidly by 20%.

PDLLA and HA ultra-fine powders were synthesized by the ring opening polymerization and the liquid phase deposition, respectively. HA/PDLLA composites were prepared by using the liquid phase absorption method. The degradation processes of HA/PDLLA and PDLLA were investigated in vitro and in-vivo. The results show that HA/PDLLA composites have higher mechanical strength and slower degradation rate than pure PDLLA, and avoid losing mechanical strength at the initial implantation stage. The HA granules break off from the surface; fibroblast starts growing and fresh callus come into being. This indicates that HA/PDLIA composites have good biodegradability, certain bioactivity and osteoconductibility. A favorable biocompatibility can be seen on the material/bone interface. At 24 ^th week, the materials are separated and enwrapped by tissue, and the fracture healed up successfully. Consequently, HA/PDLLA composites have sufficient mechanical strength for the fixation of fractures and osteotomies in cancellous bone.

Finite Element Analysis (FEA) method was adopted to establish the thermal/structure model for planar SOFC and simulate the distribution of thermal stress and displacement caused by a uniform temperature field as a consequence of coefficient of thermal expansion (CTE) mismatch among the SOFC component materials. The calculated results were analyzed and discussed, which can be used as the guide for the single cell materials selection and structure design. The calculations indicate that the maximum stress appears on the electrode/electrolyte interface; the value and distribution of the interface stress are the functions of electrode material CTEs and applied temperature field. FEA software ANSYS was employed, and according to the structural characteristics of the planar SOFC, the procedures of establishing model, defining nodals, applying load and calculating were performed.

The transparent sapphire crystal of 240mm in diameter, 210mm in length and 27.5kg in weight was grown successfully along a axis by the SAPMAC method. The relationship between temperature field distribution, growing speed, cooling rate and the density of defects, crack of crystal was discussed theoretically. The optimized temperature field distribution and process control to grow large scale crystals by the SAPMAC method were designed. Large scale sapphire rod and plank window were manufactured with special equipments. The infrared transmittance property of a standard specimen was measured as well.

TiO₂ nanotube arrays photoelectrodes were fabricated by anodic oxidation on a pure titanium sheet. The morphology and structure of the nanotube arrays were characterized by SEM and XRD. Oxidation parameters for preparation were investigated. The photoelectrochemical properties of the TiO₂ nanotube arrays electrodes were evaluated by steady-state photocurrent response. The results show that the vertical oriented TiO₂ nanotube arrays can be obtained at 20V for 30min in 1wt% HF solution. And the aperture size of nanotubes is about 90nm and the thickness of tube wall is about 10nm. The structure of nanotube arrays is a mixture of anatase and rutile through annealed at 600℃. The results of photoelectric testing show that photoelectrochemical properties of TiO2 nanotube arrays electrode annealed at 600℃ are optimum. Compared with TiO₂ nanoporous films, the properties of the TiO₂ nanotube arrays are enhanced remarkably.

Transparent and compact ZnO thin films with high c-axis preferred orientation were galvanostatically deposited in Zn(NO ₃)₂ solutions on the ITO substrate after an electrochemical pretreatment process. The crystallinity, microstructure of surface and cross section, and optical properties of obtained films were characterized by X-ray diffraction, scanning electron microscope and optical transmittance spectra. Results show that the deposition time has significant influences on the quality of ZnO films. At the later stage of film deposition (120min), ZnO film exhibits obvious decrease in the crystalline degree, surface smoothness, and transmittance, with the increase of crystallite sizes, which indicates that the deposition time must be optimized to obtain the electrodeposited ZnO film with high quality. In addition, the film thickness linearly changes with deposition time, illustrating the possibility to control the film thickness by deposition time.

[101] oriented Li:ZnO thin films were prepared on limeglass substrates by using a r.f. magnetron sputtering method. The effect of annealing temperature on the optical properties of Li:ZnO thin films was investigated. Comparing with [002] oriented Li:ZnO film, the as-deposited [101] oriented film has wide band gap (E_g), though it red-shifts from 3.37 to 3.29 eV after annealing at 560-580℃, companying with the shrinkage of unit cell. When the [101] oriented Li:ZnO film is annealed at high temperature (610℃), its band gap shifts back to 3.35eV. The photoluminescence (PL) studies confirm that there exhibit 399nm, 421nm and 468nm PL peaks for all the films. However, when the films are annealed at 560--580℃, the near-band-edge (NBE) emission peak at 380nm of the samples disappears and the band-to-band UV emission near 360nm slightly shifts to large wavelength due to the decrease of E_g. It is considered that the PL peak of 399nm is induced by Li dopant and the other peaks are arisen from the intrinsic defects in ZnO lattice structure. The effects of Li dopant on the structural and optical characteristics were also iscussed.

Anatase TiO₂ and TiO₂/Al₂O₃ films were successfully prepared on foam nickel substrates by sol-gel technique. The characteristics and photocatalytic activities of the TiO₂ and TiO₂/Al₂O₃ films were investigated by XRD, FE-SEM, etc and by photocatalytic degradation reactions of gaseous acetaldehyde under ultraviolet light irradiation, respectively. The TiO₂ and TiO₂/Al₂O₃ films coated on foam nickel substrates display a high photocatalytic activity for the degradation of acetaldehyde. Compared with the onefold TiO₂ films coated on foam nickel, the TiO₂/Al₂O₃ films show much higher photocatalytic activities. It is confirmed that photocatalytic activities and stabilities are enhanced by coating Al₂O₃ as transition layer on foam nickel, which increase the specific surface areas of substrate surface and absorption property, resulting in increase in the photocatalytic activity.

A novel SiW11/SiO2/PVA hybrid film was fabricated by using a sol-gel method. Mono-vacant Keggin-type polyoxometalates [Xn+ W11O39] (12-n)- (SiW11) were introduced into SiO2 network. The IR spectrum indicates that the covalent bond of W--O--Si is formed between SiW11 and SiO2 network, and SiW11 anions still maintain Keggin structure basically in the hybrid film. However, the strong reaction between SiW11 and matrix brings big shape changes on SiW11 anions. The transparent film changes from colorless to dark blue under UV irradiation and shows a good photochromic havior.

Low temperature spectra of SrB₄O₇:Pr³⁺, LaB₃O₆:Pr³⁺ and LaMgB₅O₁₀:Pr³⁺
were investigated by synchrotron radiation VUV light. Under VUV excitation,
photon cascade emission was found in SrB₄O₇:Pr³⁺, LaB₃O₆:Pr³⁺ and LaMgB₅O₁₀:Pr³⁺. All peaks in emission spectra were assigned. Because high phonon energy in borates results in non-radiative relaxation between ³P₀ and ¹D₂ states of Pr³⁺, the second step emission ³P₀→3H_J is very low in SrB₄O₇:Pr³⁺ and even is absent in LaB₃O₆:Pr³⁺ and LaMgB₅O₁₀:Pr³⁺. In the excitation spectra of LaB₃O₆:Pr³⁺ and LaMgB₅O₁₀:Pr³⁺, along with the 4f5d absorption bands, a weak line due to ³H₄→ ¹S₀ transition also was detected. From the position of ³H₄→ ¹S₀ transition, the energy difference of ¹S₀ state and the lowest 4 f5d state was determined.

The YBCO films were directly deposited on the {110} <011> textured Ag substrates by an ultrasonic spray pyrolysis method using the modified device. The YBCO film made by one step deposition at 900℃ on textured Ag substrate has a weak in lane texture and low Jc value. The observed white points in this film consist of high content of Ag on the surface of this film, which are due to the vaporization and diffusion of Ag atoms at high deposition temperatures. While the performance of YBCO films can be significantly enhanced by using twostep deposition route, firstly predepositing the precursor film at 700℃ then carrying out the second step depositing at 900℃.The results show that the two-step deposition can effectively prevent Ag atoms from vaporizing and diffusing into YBCO films and improve the surface roughness, texture and superconducting properties of YBCO films. The YBCO film being 15cm long, coated on {110}<011> textured Ag tape by this two-step deposition method exhibits a transport Jc value of more than 10⁴A/cm² at 77K.

In a system of electron assisted hot filament chemical vapor deposition, nanocrystalline diamond films were deposited at 1kPa reaction gas pressure with different bias current. The films were characterized by X-ray diffraction, field emission scanning electron microscope and semiconductor characterization system. With appliance of bias current, the films exhibit a pronounced preferential orientation of (110) planes and change of the surface morphology. When bias current is 8A, the deposited film displays finest grain and smoothest surface. Formation of preferential orientation of (110) planes and its influence on electrical properties of the films are discussed under the condition of electrons bombardment and lower reaction gas pressure.