Being considered as a dominant factor for its failures, the field-induced fatigue of piezoelectric ceramics is a gradual degradation of piezoelectric properties under applied cyclic loading and becomes a hot topic in the world in recent years. The fatigue mechanisms and influential factors of piezoelectric ceramics under applied electric field or multi-fields (stress-electric-temperature) were reviewed in this paper. Furthermore, the development trends in this area were proposed too.

Cu-based transparent conducting materials (TCMs) have many special properties, so they can be used in many application fields such as panel display, transparent transistor, and solar photovoltaic energy systems. In this paper, the recent achievements on the TCMs of some Cu-based oxides and oxysulfides are reviewed, which are focused on the structure chemistry and conducting mechanism, considering the strong correlation between structure and performance. It is pointed out that conducting [Cu₂S₂] layers are quite common and important for p-type conducting, and the layered-structure will promise a wide band gap for the materials.

The time-dependent and three-dimensional turbulent mathematics model is established for the flow and heat transfer of GaAs melt in the Czochralski system. The flow transitions in the melts are predicted. When the combined buoyancy and Marangoni forces induced by temperature gradient are comparable to the combined centrifugal and coriolis forces induced by crystal rotation, the flow in the melt is non-axisymmetric, and when either of them is dominant, the flow is axisymmetric. Baroclinic thermal wave is observed in the non-axisymmetric flow. The mechanism of to non-axisymmetric flow is the baroclinic instability. The flow regime diagrams classifying the flow mode under different onditions are obtained. The calculated results can be taken as a reference for growth of GaAs single-crystal with high quality.

Base on the crystallization behavior of the ZnO-PbF₂ system, a flux Bridgman growth technique with a gas cooling system was developed for the growth of ZnO crystal. By optimizing the growth parameters, transparent ZnO crystal with the size of φ25mm×5mm was obtained from the high temperature solutions. As-grown crystal has wurtzite structure with lattice parameters a=0.3252nm and b=0.5209nm, respectively. The preferred growth direction of the ZnO crystals is [0001] determined by X-ray orientation. The growth results show that the flux Bridgman method is a potential approach to grow large size ZnO crystals at low cost.

The temperature dependence of luminescence and decay time under optical excitation from Li₆Gd(BO₃)₃:Ce single crystals was investigated in the temperature range of 80--500K. The Ce³⁺ emission under the direct Ce³⁺ excitation (346nm) shows the temperature dependence different from that under the Gd³⁺ excitation (274nm). The former is governed mainly by the thermal quenching effect and the later is determined collectively by the energy transfer from Gd³⁺ to Ce³⁺ and the thermal quenching of the Ce³⁺ emission. Below 200K, the luminescence intensity under the 274nm excitation is enhanced with the temperature, which is attributed to the increase of the energy transfer rate from Gd³⁺ ions to Ce³⁺ ions. Beyond 200K, the luminescence intensity under the 274nm excitation is dominated mainly by the thermal quenching effect and decreases with the temperature. Decay times at different temperatures from 80K to 500K were measured and two distinct decay changing trends were observed. The decay time increases slightly with the temperature below 225K, which is ascribed to a photon trapping effect. Beyond 225K, the decay time reduces gradually when the temperature is increased, which is caused by the increase of the non-radiative relaxation rate. The activation energy calculated by using the classical thermal quenching equation, 0.33eV matches well with that deduced by using the Arrhenius law, 0.32eV.

Absorption spectra and up-conversion emission spectra of Er³⁺-doped silicate glasses were investigated. The intensity parameters Ω_λ(λ=2,4,6), the oscillator strength, the spontaneous transition probabilities and the fluorescence branching ratios were calculated by the theory of Judd-Ofelt. The up-conversion emission spectra show there are stronger green light and red light centered about 522nm, 545nm and 658nm, corresponding to the transition of ²H_11/2→⁴I_15/2、⁴S_3/2→⁴I_15/2、⁴F_9/2→⁴I_15/2, and the slope of fitted lines is 1.76, 1.94, 1.67, respectively, which indicates a two-photon process for the green and red light. The up-conversion mechanisms are determined to be excited state absorption and energy transfer.

The glass-forming, the crystallization process and microwave dielectric properties of MgO-Al₂O₃-SiO₂-TiO₂ system glasses adding CeO₂ were investigated by means of DTA, XRD, SEM. Results show that spontaneous
crystallization of the MgO-Al₂O₃-SiO₂-TiO₂ system glasses is obviously prevented with the increass of CeO₂ content. After heat treatment (nucleation at 770℃ for 4h and cryatal growth at 1200℃ for 1.5h) the crystallized volume fraction of rutile and cordierite decrease and that of perrierite increases. The glass-ceramics obtained by crystallization of the glasses have dielectric constant of 7.5--10.5, and microwave loss less than 5.5×10^-4.

Manifold mixed precursors were prepared with Ni(CH₃COO)₂·4H₂O, Co(CH₃COO)₂·4H₂O, H₂C₂O₄·2H₂O and different surfactants by solid state reaction at room temperature; then they were put into a bain-marie to keep 2d at 60℃. After these precursors analyzed by TG-DTA, and decomposed at 610℃, the phase and topography of the thermolysis products were characterized by XRD, SEM. The nanometer composite oxide NiCo₂O₄ with different topography was obtained. The experimental results show that these surfactants act as soft-templates, they have evident effect on topography of products.

By using Nb₂O₅ and Ta₂O₅ as precursors, nanocrystalline potassium tantalite niobate KTa_0.6Nb_0.4O₃ (KTN) powders were prepared by hydrothermal and solvothermal (isopropyl alcohol) synthesis processing. The relations of crystal structure and the synthesis conditions of KTN powders were investigated. All results of measurement on samples obtained demonstrate that the microstructure and morphology of nanocrystal powders depend on the reaction temperature, pressure and pH values of solvents. The reaction solvents are very important factors. The KTN with pyrochlore structure fabricated by the hydrothermal method shows although the amounts of pyrochlore phase in samples decrease gradually as the pH values of solvents increasing, pure perovskite phase will be gained first and last. KTN ceramic powders with perovskite structure were successfully synthesized via solvothermal processing with 1--2mol/L of KOH at 523K for 8h. The SEM images of powders show that the shape of particles is mainly cubic and the size of particles is 30--50nm.

Multi-armed CdS nanocrystallites were prepared via the hydrothermal method, in which CdCl·2.5H₂O and (NH₄)₂S acted as the starting materials. The as-prepared products were characterized by TEM, ED, SEM, RAMAN, PL, respectively. Different ligants were chosen as the assistance agent to investigate their effects on the multi-armed CdS nanocrystallites. It was found that the yields of multi-armed CdS nanocrystallites were 2%, 35%, and 85% when ethylenediamine, methylamine and ethamine were employed as the assistance agent. Only nano-particles of CdS were observed when ammonia was used. In addition, the mechanism for the formation of multi-armed CdS nanocrystallites was primarily discussed.

A dialysis membrane was used to make H⁺ and Cl^- dialyze out slowly during the hydrolysis of TiCl₄, and then TiO₂ gel was obtained. The gel was dried by different methods and then calcined. The samples were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), BET surface area and BJH pore size distribution. For comparison, the hydrolysis of TiCl₄ by the methods of heating and adding ammonia, and the hydrolysis of tetrabutyl titanate by the sol-gel method were researched. The product prepared by the dialysis method has an enormous specific surface area and the crystallites are small and uniform. It has a high phase transform temperature, keeping anatase after calcination at 700℃ and transforming into rutile phase at 900℃.

During the process of peptization and hydrothermal crystallization, the aggregation behavior and the resulting morphology of nanocrystalline titania (TiO₂) were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and dynamic light scattering (DLS) techniques. The results show that during peptization process the mixture of rutile-type and anatase-type primary particles with 10--15nm in diameter formed by peptizing the precipitated amorphous titania are transformed into rod-like secondary crystalline grains with sizes of (30--50)nm×(80--100)nm through an oriented aggregation mechanism, which obey a crystal face-matching rule. In the process of hydrothermal crystallization under 180℃, however, the rod-like secondary crystalline grains are first broken into nanoparticles with diameter in the range of 10--15nm (namely the same sizes as those of the primary particles), and the formed nanoparticles then grow in hydrothermal solution. The finally resulting particles with the sizes of 10--30nm (spherical anatase) and 20--60nm (rod-like rutile) are found to have a higher crystallization degree than the primary particles formed in the process of peptization.

Al₂O₃-LaPO₄ composite powders were synthesized by low-temperature combustion synthesis using Al(NO₃)₃, LaPO₄ and citric acid as raw materials. The relative density of hot-pressed ALC50(prepared by combustion-synthesized powders) was 98.5% and improved 2.5% in comparision with ALM50 (prepared by ball-milling of powders mixtures). It is shown that the average grain size of ALC50(0.56μm) is μch smaller than that of ALM50 (1.74μm). The bending strength and fracture toughness of ALC50 are respectively increased by 11.1% and 11.2% while the hardness of ALC50 is almost the same. The drilling rate of ALC50 increases by approximately 50% as compared with that of ALM50 due to the increasement of weak interface.

The negative thermal expansion material cubic phase ZrW_1.7Mo_0.3O₈ powder was synthesized by using zirconium oxynitric, ammonium tungstate and ammonium molydbate as raw materials. X-ray powder diffraction (XRD), thermogravimetric analysis (TG-DSC), Fourier transform infrared spectroscopy (FT-IR), scanning electron
micrograph (SEM) were used to study the crytallization process of the precursor, crystallinity and crystal morphology of the resulted product.
The results show that pure cubic ZrW_1.7Mo_0.3O₈ are prepared, and the particle size distribution is relatively uniform. In the temperature range from ambient temperature to 700℃, the intrinsic and macro thermal expansion coefficients of cubic ZrW_1.7Mo_0.3O₈ are -6.61×10^-6K^-1 and -5.76×10^-6K^-1, respectively.

Potassium tartrate (K₂tart), potassium citrate (K_3cit) and dipotassium ethylene diamine tetraacetate (K₂edta) can be used to prevent and cure calcium oxalate (CaOxa) stones. It was investigated that the modulation of the mixed potassium carboxylates of these three compounds on the crystallization of CaOxa in gel system by a double diffusion technique. The results show that the mixed carboxylates can either induce more calcium oxalate dihydrate (COD) and trihydrate (COT) crystals, or decrease the size and special surface area of calcium oxalate monohydrate (COM). For the mixture of K₂edta and K₃cit, the twisted COD crystals are grown. These twisted COD crystals look like the morphology of the COD grown in healthy human urine and have a less (100) crystal face, which can decrease the retention and adhesion of COD crystals on the surface of renal tubular cells. All these effect can inhibit the formation of CaOxa stones. It demonstrates that the mixed potassium carboxylates have better inhibitive effect than any of the single.

The olive-type LiFePO₄ was synthesized via sintering the amorphous LiFePO₄ obtained by chemical reduction and lithiation of FePO4, using VC as reducer and lithium acetate as lithium source in alcohol solution. The influences of sintering
conditions on the physical and electrochemical properties of resulting LiFePO₄ were investigated. XRD and SEM tests show that increasing the sintering temperature and time leads to higher crystallinity, but to a larger particle size. The electrochemical property of LiFePO₄ sintered at 600℃ for 2h is the best, its initial discharge capacity at 0.1C rate can reach 159mAh﹒ g^-1, its capacity after 50 charge-discharge cycles is nearly no decay.

Rock salt-type LiTiO₂ was prepared by treating TiO₂(anatase) powder with concentrated aqueous solution of LiOH at 110℃ under atmospheric pressure and characterized by means of TEM, XRD, XPS and TG/DTG. The results show that rock salttype LiTiO₂ prepared by this method is a nanosized nonstoichiometric compound. Its crystal form is stable at annealing temperature ≤500℃. In air ambience, the rock salt-type LiTiO₂ possesses stronger water absorption.

The pressure-temperature phase diagram of BaTiO₃ was investigated by using a modification of the standard Landau potential to take account of quantum saturation of the order parameter. At low temperatures, each phase boundary bends sharply down, and this non-linear behavior is associated with quantum mechanical effects. Saturation temperature θ_s characterizes the extent of quantum mechanical, and is related to the extent to which changes in the hard phonon modes influence the transition mechanism.

The electrical resistivity, magnetization, and ultrasonic velocity were investigated systematically in polycrystalline (Nd_0.75Na_0.25)_1-x(Nd_0.5Ca_0.5)_xMnO₃ (x=0, 0.25, 0.5, 0.75, 1). A charge ordering transition was observed in
all samples through resistivity and magnetization measurements. With increasing Na content, the charge ordering transition temperature (T_co)
shifts to lower temperature, the magnetization of the system is strengthened
and charge ordering becomes more unstable and short-ranged. It is found that
the longitudinal sound velocity shows a dramatic softening and stiffening around T_co. The ultrasonic anomaly near T_co indicates the existence of strong electron-phonon interaction, which originates from Jahn-Teller effect of Mn^3+. By fitting the experimental longitudinal modulus above T_co with the cooperative
Jahn-Teller theory, one can establish that the Jahn-Teller coupling energy E_JT decreases with increasing Na content. The analysis of experimental results suggests that the charge mismatch should be the main reason for the suppression of the charge ordering and the weakening of cooperative Jahn-Teller effect.

A series of SrFe(Cu,Ti)O_3-δ membrane materials were synthesized by a citric acid complex method. The crystal structures and phase stabilities of the materials were studied by TG-DSC and XRD. It is found that Cu and Ti doping content has great effects on the phase component and the oxygen permeability of the materials. The addition of Cu can increase the oxygen vacancy concentration and the addition of Ti can enhance the structure stability.
SrFe_0.6Cu_0.3Ti_0.1O_3-δ has pure perovskite structure and exhibits high stability and high oxygen permeation flux which is 0.7mL﹒min^-1﹒cm^-2 (STP) under air/He gradient at 900℃.

Carbon nanotube-fused silica composite powders were synthesized by a sol-gel method, and then the composite powders were hot-pressed to obtain relatively dense composites. Complex permittivity spectra of these composites were obtained at 8--12GHz. The experimental results show that the complex permittivity increases as the volume content of carbon nanotube increases in the measured frequency region. High imaginary permittivity reveals that these composites exhibit considerable dielectric loss. Refection loss of these composites calculated with transmission-line theory shows that these composites have obvious electromagnetic wave absorption ability and the reflection loss is sensitively relative to the thickness of composites and the volume content of carbon nanotube. The absorption properties of the composites are also improved by designing two-layer carbon nanotube-fused silica composites.

The thermal shock resistance of Al₂O₃/TiC(AT) and cobalt-coated Al₂O₃/TiC(ATC) composites was measured by the indentation-quench technique. The experimental results show that cobalt-coated Al₂O₃/TiC composites exhibit better crack extension resistance and cyclic thermal shock resistance than Al₂O₃/TiC, and the critical temperature difference for ATC composites improved 25℃ compared with that of the AT composites. Calculated results of thermal shock resistance parameters R , R', R^IV and R_st show that both the resistance to thermal shock fracture and thermal shock damage of ATC composites are better than those of AT. The thermal physic parameters are changed very little but the flexure strength and fracture toughness of ATC composites are improved greatly by introducing 3.96vol％ cobalt into AT composites using an electroless method, which contribute to the higher thermal shock parameters. In a word, the better thermal shock resistance should be attributed to the higher flexure strength and fracture toughness of ATC.

The mechanical behavior and damage process of a three-dimensional woven carbon/silicon carbide (C/SiC) composite under in-plane shear loading were investigated with IOSIPESCU specimens in relation with the failure mechanisms and the fiber architecture. The C/SiC composite exhibited several interesting features including an essentially non-linear stress-strain behavior and permanent deformations. The results show that the major damage mechanisms are matrix microcracks cracking, interface debonding and fiber breaking. The delamination cracks affect mainly the stress-strain behavior and the mechanical properties. A damage model is proposed based upon continuum damage mechanics to describe the damage evolution.

Ag/ α-Al₂O₃ interfaces of O-, Al-, and Al2-termination were calculated by an ab initio method. The dependence of the stability of the interfaces on O₂ partial pressure at 1300K was built through the so-called ab initio thermodynamics. Two approaches were performed to bridge the gap between ab initio calculation and real experimental condition, corresponding to analyzing data based on either Al chemical potential or O chemical potential respectively. The approaches caused a 4 order of magnitude difference of the O₂ partial pressure at which interfacial structure transits from Al-termination to O-termination. Further analysis shows that the real transitional point should fall in between the results from the two approaches, and the result based directly on Al chemical potential is closer to the real point. Our results show the same trend of interfacial stability in comparision with the reported wetting experiments, and the predicted transitional points for different terminations are also close to
experimental one.

The bio-mineralization properties of the melt-derived bioglass 45S5 and the sol-gel derived bioglass 58S and 77S in vitro were investigated. The effect of ionic products from bioactive glass dissolution on osteoblast proliferation and ALP activity was also discussed. The results show that osteoblasts cultured with 77S conditioned DMEM show better cellular viability and ALP activity when compared to 45S5 and 58S, though the bio-mineralization of 77S shows a little worse---only HA can form from 77S when HCA can form from 45S5 and 58S. By comparing the Si concentrations in bioglass conditioned DMEM and control DMEM, it can be concluded that solutions containing high Si concentrations in certain range are mitogenic for bone cells.

The adsorption of H₂ and H₂NCH₂CH₂NH₂ on the nickel-phosphate-basis
molecular sieves VSB-1 and CoVSB-1 was studied. The adsorption of H₂ is a supercritical physisorption. The adsorption quantity of H₂NCH₂CH₂NH₂ on VSB-1 and CoVSB-1 is larger than that of H₂O, C₂H₅ OH and other vapor of organicamines. VSB-1 and CoVSB-1 can adsorb 19.7wt％ and 24.3wt％ of H₂NCH₂CH₂NH₂ respectively. The chemisorption mechanism of H₂NCH₂CH₂NH₂ on VSB-1 and CoVSB-1 was verified by using XRD, FT-IR and UV-Vis characterization. The large adsorption quantity of H₂NCH₂CH₂NH₂ is caused by the chelation between H₂NCH₂CH₂NH₂ and the active sites of Ni and Co
in the frameworks of VSB-1 and CoVSB-1.

Nano-size Al powders were dispersed by ultrasonic vibrations to avoid reuniting and doped to the MgB₂ bulk material uniformly. The effects and mechanism of doping were studied. The phase analysis and microstructure analysis show that Al atoms can dope into the lattice of MgB₂ and substitute the site of Mg atoms. With the increase of addition, the crystal parameters a and c of MgB₂ decrease gradually and the value of c depresses more, and the critical temperature T_c of MgB₂ depresses too. The value of T_c is 35.5K for the superconductor with 8mol％ addition, while 38.5K for the pure MgB₂ bulk superconductor. The results of our research demonstrate that the superconductivity of MgB₂ with nano-Al doping is improved at the conditions of low temperature, high magnetic field and low level addition, the high level addition can restrain the superconductivity of MgB₂ ; the effects are the best when the value of nano-Al dopant is 2mol%.

Crackfree and small grain size perovskite-type ceramic BaPbO₃ conductive thin films were deposited onto Al₂O₃ substrates by a modified sol-gel method using ethylene diamine tetra-acetic acid (EDTA), citric acid, and tartaric acid as the complex chelate agent. XRD, SEM, and EDS tests, together with resistivity date,
show a good correlation among the Pb to Ba ratio, grain size, and sheet
resistance. Experimental results demonstrate that BaPbO₃ thin films with
homogeneous composition can be prepared by the method mentioned above.
Sheet resistance of BaPbO₃ thin films decreases with Pb to Ba ratio or grain size increases. The influence of heat treatment on sheet resistance is related with the thickness of BaPbO₃ thin films. The best electrical properties were obtained upon a rapid thermal anneal (RTA) at 700℃ for 10 min. Perovskite BaPbO₃ films with sheet resistance of 5.86Ω﹒□^-1 were derived from 20 spin-coating layers and annealed at 700℃ for 10min.

FeS₂ thin films with different grain sizes were synthesized by the sulfuration reaction of Fe films with different thickness at 673K for 20h. The microstructure, microstress and optical absorption of the films were investigated. The average grain size of the FeS₂ films changes from 40nm to 80nm when the film thickness changes from 120nm to 550nm. The internal microstrain, lattice distortion, absorption coefficient and energy gap decrease with the grain size increasing. The mechanism responsible for the result can be attributed to the variation of
the degree of microstress, the distribution of energy level of crystal defect
states and the height of grain boundary barrier due to the change of the
crystal planar defects density with the grain size changing.

A series of polyimide/TiO₂ composite membranes supported on TiO₂ /kieselguhr-mullite (K-M) were prepared via a sol-gel process. Their morphologies, chemical structures, thermal performances, pore distribution and gas permeability were characterized by transmission electron microscope (TEM), Fourier transform infrared (FTIR), solid-state ¹³C CP/MAS NMR, thermogravimetric analysis (TG/DTA), N₂ adsorption and gas permeability measurement. The results show the TiO₂ phase is well dispersed in the polyimide matrix. The TiO₂ phase is connected with the polyimide through the pendant carboxyl along the polyimide chain. The polyimide/TiO₂ composite membrane possesses finely thermal stability. The composite membranes show higher separation properties for H₂, CO₂, N₂ and H₂O when compared to pure polyimide. The separation factors of the polyimide/TiO₂ composite membranes with 5wt% TiO₂ contents for H₂/N₂, CO₂/N₂ and H₂O/N₂ are
64.2, 42.5 and 80.8, respectively.

The coatings of SiC were prepared from the methyltrichlorosilane (MTS) by low pressure chemical vapor deposition from 950℃ to 1300℃. SEM was used to characterize the surface and cross-sectional morphologies of the as deposited coatings. The effects of temperature on the microstructures of SiC coatings were investigated. At 950℃, the as-deposited SiC coating is loose and the grains of the coating are fine. In the temperature range of 1000-1100℃, CVD SiC coatings show a dense and smooth surface morphology. However, in the temperature range of 1150-1300℃, the surface morphology of SiC coatings changes to rounded hillocks and the as-deposited coatings are very rough. Factors influencing the surface morphologies and structures of SiC coatings were studied through thermodynamics and nucleation-growth theory. The relationship between deposition temperature and SiC coatings’ cross-sectional morphologies can by listed as follows, the as deposited coatings are very dense and there are no holes when the deposition temperature is lower than 1200℃, however, the as deposited coatings become very loose at 1300℃. The inside structures of SiC coatings were interpreted by the island growth
model.

Experiments using a planar metal disc flyer driven by explosives and a cylindrical chamber was designed to synthesize cubic silicon nitride with the mixtures of α-Si₃N₄ and copper powders as starting materials. Shockcompressed samples were successfully recovered. The recovered samples were nitrated to resolve copper, and the separated silicon nitride powders were analyzed by XRD. The results indicate that most of α- Si₃N₄ are transformed into cubic silicon nitride when a shock pressure larger than 50GPa and a matched shock temperature simultaneously load on α-Si₃N₄. The experiments provide a shock compression technique that can synthesize cubic silicon nitride in the order of gram mass in one test run, which lay the foundation for conducting further investigation on the properties and performance of cubic silicon nitride.

The CaZrO₃ powder precursors were prepared from raw material of Ca(OH)₂ and ZrOCl₂, KOH as the mineralizer, under the hydrothermal reaction conditions of 15-250℃ and 6-12h. The CaZrO₃ powder was obtained by calcing the precursors at 900-1000℃. The article discussed the effects of the ratio of Ca to Zr in raw material, crystal temperature, crystal time and pH of solution on the structure and state of the product from hydrothermal synthesis, as well as the effect of calcing temperature on the crystal microstructure of CaZrO₃. The results of XRD and SEM show that the crystal of CaZrO₃ can be obtained under the conditions of n(Ca):n(Zr)=2:1, at 200℃, for 6h and calcing temperature of 900℃. With the rising of synthesis temperature, the lasting of crystal time and the rising of calcing temperature, the crystal grain size increases, and has less aggregation. When the particle size is in the range of 0.5-3.0μm,the CaZrO₃
powder has a good sintering activity and may be used as a refractory.

Nanometer manganese dioxide microspheres were prepared from sodium pyrosulfite acid and potassium permanganate via using W/O emulsions as template. SEM, TEM, XRD and FT-IR were used to characterize the MnO₂ micropheres. The SEM and TEM images showed that the average diameter of the MnO₂ micropheres was about 150nm. The XRD analysis indicated that the MnO₂ micropheres was of non-crystalline and active. According to the experimental facts and characteristic of the products, the formation mechanism of the microsphere was discussed.

Nd³⁺:Gd₃Ga₅O₁₂ (Nd:GGG) single crystals were grown by the Czochraski method. Specific heat and thermal diffusivity of Nd:GGG single crystals were measured with differential scanning calorimetry and laser flash methods, respectively. The thermal conductivity of Nd:GGG was calculated, and consistent with the thermal conductivity measured with PPMS. The experimental results indicate that Nd:GGG single crystal has good thermal properties such as high specific heat and thermal conductivity. Thermal diffusivity and thermal conductivity of Nd:GGG single crystal vary with temperature. The higher temperature is, the lower thermal diffusivity and the thermal conductivity are. The Debye temperature of Nd:GGG is 711K.

ZnO has recently become a very popular material due to its great potential for
optoelectronics applications. To realize practical application of short-wavelength optoelectronic devices (such as LEDs and LDs) based on ZnO materials, electroluminescence (EL) from ZnO p-n homojunction is pivotal. In this article, ZnO homojunction was grown on single-crystal GaAs (100) substrate by ultrasonic spray pyrolysis with Zn(CH₃COO)_2^﹒2H₂O as precursor solution. CH₃COONH₄ and In(NO₃)₃ aqueous solutions were chosen as the doping sources of nitrogen and indium respectively. The ZnO homojunction was comprised of N-In codoped p-type ZnO and unintentionally doped n-type ZnO film. Ohmic contact layers on n-type ZnO layer and GaAs substrate were formed by Zn/Au and Au/Ge/Ni electrode respectively. Moreover, light emission was observed under forward current injection at room temperature, the emission could be clearly seen by the naked eye in a darkened room. With the demonstrated success of electroluminescence from ZnO p-n homojunction at room temperature, the application of short-wavelength optoelectronic devices based on ZnO materials should be possible in the near future.

A novel technique was developed to prepare Li₄Ti₅O₁₂ anode material for lithium secondary batteries. Solution of Ti⁴⁺ was prepared by TiCl₄ as the raw material and then the spherical precursor was prepared via an “outer gel” method. Spherical Li₄Ti₅O₁₂ powders were synthesized by sintering the mixture of spherical precursor and Li₂CO₃. The influence of temperature on performance of product was studied. The investigation of XRD, SEM and the determination
of the electrochemical properties show that the Li₄Ti₅O₁₂ powders prepared by this method are spherical, narrowly distributed, well crystallized. The Li₄Ti₅O₁₂ powders also have excellent fluidity and excellent electrochemical performance.
The tap-density of the product tested is as high as 1.80g﹒cm^-3. Between 1.0 and 3.0V versus Li, the initial discharge specific capacity is as high as 160.7mAh﹒g^-1, and the discharge specific capacity of the 20 th cycle is 150.2mAh﹒g^-1. Study shows that this method is appropriate for preparing Li₄Ti₅O₁₂ with high tap-density and high electrochemical performance.

Carbon nanotubes and Ga-doped carbon nanotubes were synthesized by
pyrolysis and then purified. Thin films of the purified samples were fabricated
by a screen-printing method. Field emission properties of these films were
studied. It was shown that the turn-on field of carbon nanotubes and Ga-doped carbon nanotubes was 2.22V/μm and 1.0V/μm, and the current densities were 400μA/cm² and 4000μA/cm² for carbon nanotubes and Ga-doped carbon nanotubes at applied fields 2.4V/μm. The electron field emission properties of the gallium-doped nanotubes were much better than those of carbon nanotubes. Mechanisms of field emission of gallium-doped nanotubes were explained.

In order to improve hearing ability, piezoelectric materials were directly used to cochlea implants based on piezoelectric characteristics which could transform acoustic vibration into electric signal. A series of experiments were done to substantiate the feasibility of the different piezoelectric cochlea implants in vitro and in vivo. The unpoled ceramic had no piezoelectric characteristic and no ability to decrease the threshold, while the poled ceramic had obvious piezoelectric effect to recover the hearing. Based on these results, it can be affirmed that the piezoelectric cochlea implant can activate the nerve and decrease the threshold. In comparison with ceramics, the piezoelectric polymer is also adaptive for implant material to activate the nerve and improve hearing.

Cr₂ AlC ceramics were prepared by hot-pressing using Cr, Al and graphite powders as starting materials. The effects of composition and sintering temperature on the phase assembly and bulk density of the samples were studied. The results indicated that the phase assembly of the samples consisted of Cr₂AlC, as a major crystalline phase, together with very small amount of Cr₇C₃ for the composition with less than 20at％ excessive Al content, whereas it became a single Cr 2AlC phase in the sample for the composition with more than 20at％ excess Al. The bulk density of the samples decreased with the increase in excess Al in the composition. The hardness, flexural strength and Young’s modulus of the sample hot-pressed at 1400 ℃
for 1h for the composition Cr:Al:C=2:1.1:1 at room-temperature were 3.5GPa,
375MPa and 278GPa respectively. The electrical conductivity decreased linearly with the increase in temperature from 75K to 269K, which hinted that the electrical behavior of Cr 2AlC likes that of metal. Its thermal properties were also determined.