The traditional gate dielectric material of SiO₂ can not satisfy the need of the continuous downscaling of CMOS dimensions. High-K gate dielectric materials have attracted extensive research efforts recently and obtained great progress. In this paper, the developments of high gate materials were reviewed. Based on the authors background and research work in the area, the latest achievements of high-K gate dielectric materials on the recrystalization temperature, the low-K interface layer, and the dielectric breakdown and metal gate electrode were introduced in detail.

Highly (100)-oriented Pb(Zr_0.52Ti_0.48)O₃ thin films with different Gd dopants (PGZTx, x=0, 1mol%, 2mol%, 3mol%, 5mol% Gd) were prepared on Pt/Ti/SiO₂/Si substrates by the sol-gel technique and rapid thermal annealing (RTA) process. The dielectric properties of the PZT thin films with 1mol% Gd dopant is improved with increased dielectric permittivity and decreased dielectric dissipation. However, when Gd dopants are more than 2mol%, dielectric properties of the doped PZT thin films are deteriorated obviously including decrease of dielectric permittivity, increase of dielectric dissipation. At the saturation field, the irreversible polarization first increases when Gd content is 1mol% and then decreases when Gd contents are more than 2mol%, the reversible polarization remains almost constant in all PGZT thin films. The so-called Rayleigh law used to describe the hysteresis of ferromagnetic materials in the subcoercive regime can be extended to describe the subcoercive hysteresis in ferroelectric PGZT materials. The mechanism of the Gd dopant effect on the dielectric properties and polarization behavior is also discussed.

The effects of V⁵⁺ substitution on the sintering characters, microstructure and microwave dielectric properties of Mg₄(SbNb_1-xV_xO₉ ceramics were investigated. Results show that a small amount of V⁵⁺ substitution for Nb⁵⁺ can lower the sintering temperature of Mg₄(Nb_2-xSb_x)O₉ drastically. In all composition range investigated, the sintered ceramics show single phase with corundum structure. With increasing of V⁵⁺ content, the dielectric constant (ε) and quality factor (Q·f) increase and thereafter decrease, respectively, the temperature coefficient of resonant frequencies τ f decreases which is due to the strengthened B site-bond valence caused by V⁵⁺ substitution. The ceramics with x=0.15 sintered at 1250℃ has a relative dielectric constant ε_r of 9.98, a quality factor Q·f value of 20248GHz (at 8GHz) and a temperature coefficient of resonant frequencies τ f value of --23.3×10-6K^-1.

The tolerance factor of ABO₃-type ilmenite by analyzing the ABO₃ ilmenite crystal structure is established, and combining with the electronegativity difference, regularities governing the formation and the stability of ilmenite-type compounds are discussed. The tolerance factor equation is proved appropriate for ilmenite structure by analyzing the structure stability of some ilmenite compounds, such as MgTiO₃, NiTiO₃, CoTiO₃, ZnTiO₃ and (Zn_1-x, M_x)TiO₃ (M denote Mg, Ni, Co). According to the results of statistical analyzing the tolerance factor and electronegativity difference of the present ABO₃-type ilmenite, the
experience tolerance factor value and experience electronegativity difference value to form stable ilmenite compound are obtained, that is, t>0.80 and e>1.465.

The ultraviolet light photosensitive Ba_0.8Sr_0.2TiO₃ (BST) sol and gel films were prepared by using chemical modification and modified sol-gel process with polyvinylpyrrolidone (PVP) as crack-suppressing agent, and acetylacetone (AcAcH) as chemical modifier agent which can associate metal-salt to form coordination chelate. The BST patterned gel films were prepared by irect patterning process. Then the BST patterned films with perovskite structure on Pt/TiO₂/SiO₂/Si substrate were obtained after subsequent heat treatment. The thickness of the BST patterned film is about 793nm, the dielectric constant and dielectric loss of the BST patterned film are about 600 and 0.03, respectively.

Nano-particles of Ce-doped BaTiO₃ were prepared by sol-gel method. The structure, micrograph and microwave absorption properties of the materials were characterized by using X-ray diffraction (XRD), Raman spectroscope, Scanning Electron Microscope (SEM) and vector network analyzer. The BaTiO₃ powders doped with different Ce contents have the same crystalline tetragonal structure. With the increase of Ce content, the crystal sizes of the BaTiO₃ powders decrease with lattice constants a enlarges and c decreases. Within the bandwidth of 2--18GHz, the reflection loss of 0.2% Ce-doped BaTiO₃ powders is increased and reflection peak has blue shift compared with pure BaTiO₃ powders. Reflection losses of 0.2% Ce-doped BaTiO₃
powders are increased by 15dB and 30dB at 5.8GHz and 7GHz, respectively, and the bandwidth is widened two times. The above shows that Ce-doping can greatly improve the microwave absorption properties of the BaTiO₃ powders.

(La_0.2Bi_0.8FeO₃)_0.8-(NiFe₂O₄)_0.2 (LBFO-NFO) thin films were grown on (100) SrTiO₃ substrates by pulse laser deposition . X-ray diffraction and Field Emission Scanning Electronic Microgrape studies confirm that the phases of LBFO and NFO in the films grow along the direction of (100) and the particle sizes of the two phases are about 100--150nm, respectively. The ferroelectric and ferromagnetic hysteresis of the films measured with a standardized ferroelectric test system (RT- 66A, Radiant technologies) and vibrating sample magnetometer (VSM) show that the saturation polarization and magnetization are 7.6μC/cm² and 4.12×10⁴A/m respectively, which indicates that LBFO-NFO films possess multiferroic properties obviously. By controlling the growth condition of the films, the leakage current of LBFO-NFO films can be decreased. Accordingly, the ferroelectric and ferromagnetic properties can be enhanced greatly.

Barium-strontium titanate (Ba_0.65Sr_0.35TiO₃) films doped with Ho³⁺(1mol%, 3mol%, 5mol%, 8mol%) were prepared by the sol-gel technique. The AFM, XRD, UV-Vis spectra and photoluminescence (PL) spectra of BST films were investigated. Results show that the lattice parameters of BST films increase when Ho³⁺ dopant increases from 1mol% to 3mol% then decrease with Ho³⁺ dopant from 3mol% to 8mol%. The lights centered at about 615, 650 and 750nm are corresponding to the transitions of ⁵F₃→⁵F₇, ⁵F₅→⁵F₈ and ⁵S₂, ⁵F₄→⁵F₇, respectively. The lifetime spectra of ⁵S₂, ⁵F₄ and three PL spectra above indicate that the luminescence intensity reach the maximum in 3mol% Ho³⁺ -doped BST films. The optimized Ho³⁺ dopant in BST films is 3mol%. The crossing relaxation mechanisms and site-substituting between H ³⁺ and Ba²⁺/Sr²⁺/Ti⁴⁺ are analyzed.

Design and manufacture of pulse power equipment greatly depend on the investigation of flashover on dielectric surface in vacuum under pulsed voltage. It is expected that sputtering coating with semiconductivity and high thermal conductivity can apparently improve the surface flashover characteristic of dielectric materials. Three kinds of thin films (TiO₂, ZrO₂ and HfO₂) were sputtered on epoxy substrate using magnetron sputtering in ultrahigh vacuum. Experiments were carried out under high voltage pulse (50ns rise time and 600ns full width at half maximum) in vacuum to study the flashover characteristics of three kinds of oxide films. The experimental results show that the TiO₂, ZrO₂ films sputtered on the epoxy substrate are amorphous as they are not annealed and surface grains are not crystalized, but HfO₂ film becomes crystalized. The flashover voltage of TiO₂ film is the highest, the flashover voltage of HfO₂ film is close to the epoxy sample. The effect of puttering time on the flashover voltage is different for different target materials. The vacuum flashover voltage increases with the sputtering time increasing for TiO₂ and HfO₂ films, but decreases for ZrO₂ film. Furthermore, the effects of film properties on flashover performance as well as the distribution of surface charge after flashover are analyzed.

Nanocrystalline Gd-doped CeO₂ (GDC) ion conductor electrolyte thin films were synthesized by reactive magnetron sputtering on amorphous quartz substrates at different temperatures. The thin films were characterized by X-Ray diffraction, atomic force microscope and alternating current impedance analysis. The results show that the growth orientation of GDC films varies with the deposition temperature from strong (111) texture at 300--400℃ to random growth at 500--600℃. Growth morphologies of GDC films also transform from well-oriented big prismatic growth islands to dense small round ones with increase of the deposition temperature. The activation energy (～1.3eV) of GDC films closed to the reported value for the grain boundary conductivity indicates that grain boundary resistance dominates the electrical properties of GDC films. Conductivity varies with grain size of GDC films due to the grain boundary space charge effect, the smaller the grain size, the higher the conductivity and vice versa.

Carbon aerogel (CA)-SiO with excellent lithium insertion-extraction property could be prepared through ball-milling of carbon aerogel (CA) with SiO. Effects of ball-milling process including ball-milling time and ball-milling speed on structure and electrochemical property of CA-SiO composite were investigated. The results show that ball-milling of amorphous SiO with CA can crystallize Si with small particle size, the crystal size of Si increases with the extension of ball-milling time and the increase of ball-milling speed, and then decreases. The crystallization of Si can be improved by the extension of ball-milling time and the increase of ball-milling speed. However, ball-milling for too long time or at too high speed will result in transformation of crystal Si to amorphous. Little influence of ball-milling time and ball-milling speed is found on crystal size of C in the prepared CA-SiO, though ball-milling leads to some increase of C crystal size. CA-SiO has higher capacity and better cycling stability when the silicon within this material shows higher crystallization and smaller crystal size. In contrast, amorphous Si is disadvantageous for lithium insertion-extraction in CA-SiO which will lead to poorer cycling stability. The ball-milling speed of 400r/min and the ball-milling time of 10h are the best preparation parameters for CA-SiO used as anode material of lithium-ion battery.

Polyimide derived activated carbon was prepared by carbonization and KOH activation, which was used for electrode material of electric double-layer capacitors. Its pore structure and surface chemical property were studied by DFT and XPS, respectively, and its electrochemical properties were studied by electrochemical methods, such as, charge-discharge of constant current. The results show that both the nitrogen content and the porosity of sample CPI affect its gravimetric capacitance. After activation, the specific areas of sample API reach 1941m²/g, the micropore formed is all less than 2nm. The effect of nitrogen atom can be ignored. Its gravimetric capacitance reach 300F/g with the discharging current density of 50mA/g, and remain 86.1% of its capacitance when the current density reaches 1000mA/g. The results of impedance also show that sample API has good electric double-layer performance which is novel electrode material for electric double layer capacitor.

Monocrystalline 3C-SiC films were successfully grown on Si(111) substrate at substrate temperature of 1000℃ by molecular beam epitaxy (MBE) using solid-state element C and Si sources. The RHEED results indicate that the film grown on Si(111) substrate is 3C-SiC film with all cubic axes parallel to the substrate. The quality and the strain of the film were investigated by Synchrotron radiation X-ray grazing incident diffraction method (GID) combining X-ray diffraction (XRD). The result shows that the film is in the state of biaxial tensile strain. The biaxial tensile strain is attributed to the large lattice and thermal expansion coefficient mismatch between SiC and Si. According to the result of the rocking curves of the film at different grazing incident angles, the quality of the film is better in the zone far from the interface between SiC and Si due to the decrease of the defects in the zone far from the interface. The results of rocking curves of GID and XRD show that the tilt mosaic is bigger than the twist mosaic in the SiC film, which indicat that the lattice array in plane is in better order than that in perpendicular direction.

In the process of SiC film fabricated by chemical vapor deposition method, kinetic process of chemical reaction in reaction zone and the deposition and diffusion of matrix surface were studied respectively. With kinetic Monte Carlo method, a three-dimensional atomic-scale of {111}-oriented SiC film is established and its growth process is simulated by MATLAB. The results show that the growth of film has three stages including form of little islets, mergence and expanding of islets and dynamic balance between islets. With the increase of substrate temperature, deposition rate, surface roughness and height of film all increase. When the deposition rate increases, surface roughness increases while relative density decreases. Moreover, the simulation results are in well agreement with the relevant theory and experimental result.

Ablation properties of a 3D C/SiC composite nozzle were investigated by using hot-firing test in a small solid propellant
rocket motor. Ablation mechanisms of the C/SiC composites and effects of the combustion gases parameters were discussed. The results show that the linear ablation rate at the throat of the composite nozzle is 0.128±0.088mm/s, and the mass ablation rate is 0.166kg/(m² ·s). Ablation behavior for the 3D C/SiC composite shows a nonuniform process, which is directly affected by the compositions, temperature, pressure and the velocity of combustion gases. The ablation in the divergent section, convergent section and the regions near the throat grows severe by degrees. Ablation mechanisms of C/SiC composite are the cooperation of thermo-physical ablation, thermo-chemical ablation and thermo-mechanical erosion, which involve the decomposition of the SiC, oxidation of the SiC and carbon fiber, as well as chemical and mechanical erosion by Al₂O₃ slags and particles, respectively.

Aniline/o-anisidine copolymer (P(An-co-oAs)) intercalated graphite oxide (GO) composites were synthesized through the delamination/reassembling method using GO as host and conducting P(An-co-oAs) as guest. FTIR spectra indicate that the hydrogen bonds are formed between the amino groups of P(An-co-oAs) and the carbonyl groups on the internal layers of GO. XRD and TEM results show that the P(An-co-oAs)/GO composites maintain good lamellar structure, and the interlayer spacing of GO is enlarged with the increase of the added amount of P(An-co-oAs). The electrical conductivity of the composites is 2 to 3 orders of magnitude higher than that of the GO. The intercalation of P(An-co-oAs) also has a pronounced effect on the electrochemical properties of the GO.

ZrB₂-SiC- xwt% carbon nanotubes(x=0, 1.0, 2.5, 4.0) ceramic composites were fabricated by the hot-pressing sintering. The prepared conditions, mechanical properties and microstructure were also investigated. TEM was used to observe the microstructure and SEM was used to analyze the fracture surface and crack propagation. Then, the strengthening and toughening mechanism of carbon nanotubes were discussed. Results show that carbon nanotubes can deposit in the ZrB₂ crystal grain and form intragranular structure. When the carbon nanotubes content is 2.5wt%, the flexural strength and toughness reach 542MPa and 6.10MPa·m^1/2 respectively, with the relative density of 99.6% and Vickers hardness value of 21.7GPa. The reasons of the mechanical properties improvement are the increased compactness, grain refining and the intragranular structure caused by the introduction of carbon nanotubes.

Advanced silicon nitride ceramics with high wear resistance were fabricated by colloidal process. Orthogonal design was utilized to optimize the process parameters.The change of Zeta potential for Si3N4 particles after adding dispersant was analyzed. Furthermore, the microstructure, mechanical properties and wear resistance of silicon nitride ceramics were investigated. The results indicate that the green body with high density can be formed when the volume fraction of solid phase of silicon nitride slurry is equal to 45%. And silicon nitride ceramics with fracture toughness of 7.21MPa·m^1/2, hardness of 9.30GPa is obtained in the optimum condition. The friction and wear tests show that silicon nitride ceramics happen to crisp rupture and break off in the dry condition; while in the water-lubricated condition, the film of Si(OH)₄ is formed on the friction surface, and the wear mechanism is mainly chemical fretting wear.

Ag₂S nanoparticles were prepared in two different W/O microemulsions, the structure and morphologies of as-prepared Ag₂S nanoparticles were characterized by means of X-ray powder diffraction (XRD), transmission electron microscope (TEM). The tribological properties of liquid paraffin containing Ag₂S nanoparticles were evaluated on a four-ball test machine, the worn steel surface morphology were analyzed by using of scanning electron microscope (SEM). Results show that Ag₂S nanoparticles synthesized in two microemulsions, i.e. isooctane/sodium oleate/n-pentanol/water solution (sampleⅠ) and liquid paraffin/Span 80-Tween 80/n-butanol/water solution (sampleⅡ) both possess monocline crystal structure, and exhibit an even grain distribution. They have average particle size of 18nm and 5nm, respectively. The antiwear tests show that Ag₂S nanoparticles dispersed in liquid paraffin processed from liquid paraffin/Span 80-Tween 80/n-butanol/ water solution microemulsion exhibit good antiwear properties which can improve load carrying capacity of the base oil remarkably.

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Porous carbon was prepared by technique of phenol resin polymerization-dependent phase separation and pyrolysis. The influence of catalyst amount on pore structure of porous carbon was investigated. The results show that porous carbons with average pore size of ca. 40nm are obtained. The apparent porosity increases with increasing amount of catalyst. When the catalyst amount is 15%, apparent porosity of the porous carbon reaches 54.3%. Moreover, the carbon skeletons of the porous carbons become finer with high amount of catalyst. Volume shrinkage and gel time play important roles in changing the pore structure of porous carbons, for the porous carbons with high amount of catalyst have less shrinkage and shorter gel time during the curing.

Mixed ion exchanged Li-Ca-LSX were prepared respectively from the starting materials Li-LSX and Ca-LSX and effects of the difference on ion exchanging degree, ion location and adsorption properties were investigated via the measurements of ICP-AES, ⁷Li MAS NMR, ²³Na MAS NMR and static adsorption method. The results show that the Li-Ca-LSX prepared from Ca-LSX as the starting material reaches the exchange maximum by 31.5% and the best properties, namely the specific adsorption capacity at 36.4mL/g for N₂ and 5.0mL/g for O₂; and the N₂/O₂ adsorption selectivity at 12.4. From the results of NMR, it is found that excepting the well-known site SIII, some Li⁺ locating at the site SI’ can also affect significantly on the adsorption properties of LSX.

The Ti-KIT-1 sieve was obtained by a grafting method using tetrabutyl titanate as Ti source and KIT-1 as support. An amphiphilic Ti-KIT-1 sieve was prepared from Ti-KIT-1 modified with trimethylchlorosilane and characterized by XRD, DRS, FT-IR and nitrogen adsorption-desorption techniques. Experimental results show that the resultant amphiphilic Ti-KIT-1 sieve remains the original mesoporous structure with a smaller specific BET surface area and BJH volume of pores compared to the Ti-KIT-1 sieve. DRS and FT-IR indicate the existence of tetrahedral titanium (Ⅳ), which may act as active sites for epoxidation of olefin. The amphiphilicity of samples are measured through adsorption capacity for the vapour of water or toluene, acetone, n-hexane. The resultant Ti-KIT-1 sieve is amphiphilic due to the partial coverage of the external surface with the hydrophobic alkylsilane groups and the hydrophilicity of the rest of the surface.

Mesostuctured CeO₂ and CeO₂-ZrO₂ composite were synthesized via sol-gel method using cerium acetate and zirconium acetate as inorganic species, block copolymer P123 as surfactant, respectively. The obtained samples were characterized by XRD, N₂ adsorption-desorption, TEM, HRTEM, and SAED. Results show that the mesostrutured CeO₂ possesses crystalline framework with the average pore size of ca. 10nm. In particular, it’s revealed that the inorganic framework consists of highly oriented nanocrystals with the preferential orientation parallel to the channel arrays. In situ TEM observation equipped with the heating holder demonstrates that the mesostructured CeO₂ maintains perfect pore integrity up to 800℃ due to the confined growth tendency of oriented grains. Mesostructured CeO₂-ZrO₂ composite remains the similar framework structure when ZrO₂ molar ratio is less than 30%, however, it appears to transform to random oriented polycrystalline mesostructure when ZrO₂ molar ratio is higher than 30%.

A low-thermal-expansion ceramic composite of ZrO₂-ZrW₂O₈ was synthesized by co-precipitation route using analytically pure zirconium nitrate [ZrO(NO₃)₂·5H₂O] and ammonium tungstate(H₄₀N₁₀O₄₁W₁₂·xH₂O) as starting materials. Effects of heat-treatment on the transformation from the precursor to ZrO₂-ZrW₂O₈ composite were investigated, and the chemical reaction process of the precursor was explored. The crystal structure, phase transition, cross-section morphology and thermal expansion coefficient of the samples were investigated by X-ray diffraction(XRD), thermogravimetric and differential scanning calorimetry(TG-DSC), scanning electron microscope(SEM) and dilatometry respectively. The results show that the homogeneous ZrO₂-ZrW₂O₈ composites are synthesized after sintering at 1150℃ for 2h. With the increase of sintering time, the full width at half maximum (FWHM) of the ZrW₂O₈ diffraction peaks decreases, and the grain grows up gradually. ZrO₂-50wt%ZrW₂O₈ composite has an average thermal expansion coefficient of -3.2295×10^-6K^-1 from 30℃ to 600℃.

A new method for the preparation of fine α-Al₂O₃ powders was reported. C/γ-Al₂O₃ composites were prepared by carbonizing starch/γ-Al₂O₃ precursors. Calcining the composites under oxygen flow in a furnace at 800℃, rapid and total transformation of γ-Al₂O₃ to α-Al₂O₃ occurred when the carbon content was between 6wt%-13wt%. Characterized by N-₂ adsorption technique and SEM observation, the particle size of the as-prepared α-Al₂O₃ powders is about 2μm. By this method, γ-Al₂O₃ can be transformed in very short time of about several minutes to α-Al₂O₃ at 800℃, which is much lower than the temperature for the commercial preparation. The method is very efficient for the rapid preparation of fine α-Al₂O₃ powders. And the simple operation and cheap raw materials for the method show that it is very promising for industrial applications.

Sub-micron alumina ceramics were fabricated by spark plasma sintering technique (SPS), using commercial α-Al₂O₃ powders as starting material and MgO as sintering-aid. The effects of sintering temperature and sintering-aid content on densification and grain growth of sub-micron alumina were systemically studied. The results show that the optimal sub-micron alumina is obtained by sintering at 1250℃ for 5min under 60MPa, doped with 0.05wt%MgO. The relative density and the average grain size are 99.8%TD and 0.68μm, respectively. Moreover, the Vickers hardness can reach 20.75GPa (HV5), and the in-line transmission (1mm thickness) in the 3-5μm mid-infrared range is measured beyond 83%. However, second phase MgAl₂O₄ is found in the samples doped with more than 0.1wt%MgO, resulting in a lower transmittance because of light scattering.

The spinel-type MeFe₂O₄(Me=Zn,Ni_0.5Zn_0.5, Ni_0.4Zn_0.4Cu_0.2) ferrite fibres with diameters of 0.5-20.0μm and high aspect ratio (length/diameter) were successfully prepared by the organic gel-thermal decomposition process using metal salts and citric acid as raw materials. The structure, thermal decomposition process and morphologies of the gel precursors and the fibres derived from thermal decomposition of these precursors were characterized by FT-IR, XRD, TG-DSC and SEM, and the electromagnetic performance of ferrite fibers were measured by VSM. The results show that linear-type structural molecules for the gel precursor is formed by a single dentate liganding type or bidentate-chelating mode among citric acid and metal ions during the complexation reaction, and the gel composed of these linear-type molecules exhibits a good spinning performance. The MeFe₂O₄(Me=Zn, Ni_0.5Zn_0.5, Ni_0.4Zn_0.4Cu_0.2) ferrite fibres all exhibit a soft magnetic performance, and chemical composition, grain size and morphology have considerable influence on the magnetic properties of these ferrite fibres. The saturation magnetization(M _s) of ZnFe₂O₄, Ni_0.5Zn_0.5Fe₂O₄ and Ni_0.4Zn_0.4Cu_0.2Fe₂O₄ fibres are 2.6, 12.7 and 40.0A·m²·kg^-1, and coercivity of these fibres correspondingly are 4.77, 5.82 and 4.04kA·m^-1, respectively.

The color change resistant properties of silver and zinc-loading zeolite 4A antibacterial agent with varying contents of Ag⁺ and Zn²⁺ were investigated. The contents of Ag⁺ and Zn²⁺ of the specimens were determined by ICPS, the morphology and structure of the specimens were characterized by using X-ray diffraction (XRD), Infrared spectrum (IR) and High-Resolution Transmission Electron Microscope (HRTEM) techniques. The color change resistance properties and antibacterial performance of the specimens were examined. The results show that the color change resistance properties of the specimens are enhanced by increasing the content of Zn²⁺ and reducing that of Ag⁺ in silver and zinc-loading zeolite 4A antibacterial agent, meanwhile the antibacterial properties of the antibacterial agents are influenced little. On considering the cost, the antibacterial performance and the color change resistant properties, it is suitable for the contents of Ag⁺ and Zn²⁺ in the antibacterial agent are 0.41wt% and 3.83wt%, respectively.

Calcium cadmium hydroxyapatites with various Cd doping (Cd/(Cd+Ca))were synthesized and characterized by X-ray diffraction, FT-IR spectroscope and FESEM. TG-DTG-DSC-MS and Toxicity Characteristic Leaching Procedure (TCLP) were used to determine their thermal and chemical stability. The results show that Cd²⁺ enters into the hydroxyapatites crystal lattice. And
with molar ratios of Cd/(Cd+Ca) increasing, there forms the phases of Ca_3.9(Ca_4.7Cd_0.7)(PO₄)₆(OH)_1.8, Ca{_3.8(Ca_4.1Cd_0.73)(PO₄)₆(OH)_1.8, Ca_3.6(Ca_4.5Cd_0.76)(PO₄)₆(OH)_1.6, Cd₅(PO₄)₃OH, respectively. All the calcium cadmium hydroxyapatites are thermal stable up to 500℃, and their thermal stabilities are enhanced with the increase
of Cd doping, but their chemical stabilities become worse.

Titania coatings were deposited on titanium alloy substrates by atmospheric plasma spraying using nano TiO₂ powder as feedstock. Acid and alkali solutions were implied to modify the surface of the as-sprayed titania coatings. The bioactivity of titania coatings before and after modification were investigated by simulated body fluid (SBF) tests in vitro. X-ray diffraction, Scanning electron microscope, Fourier transform infrared spectroscope and Energy diffraction spectroscope
were used to investigate the microstructure and composition of titania coatings. The bonding strength and anticorrosion of titania coatings were also studied. The results indicate that the bonding strength between titania coating and Ti alloy substrate is 40MPa. The corrosion resistance performance of titania coating in SBF is better than that of Ti-6Al-4V alloy.
The SBF tests show that the carbonate-containing hydroxyapatite is formed on the titania coating surfaces which is treated by H₂SO₄ and NaOH. However, no bonelike apatite is formed on the surface of as-sprayed titania coating. It is concluded that the bioactivity of titania coating is improved greatly by chemical treatment.

The ultrafine bioactive glass powder (uSBG) with particle size less than 1μm was prepared by sol-gel and wet grinding methods. The biomineralization properties in SBF of the two powders (uSBG and SBG) were analyzed and compared by using FTIR, XRD, SEM. The results indicate that hydroxyl-carbonate apatite (HCA) forms on the surface of the two samples and biomineralization rate of uSBG is prompted significantly by wet grinding. pH value of SBF solution immersed uSBG for different times is lower than that of SBF for SBG, and ICP tests show that the releasing rules of ions are different between uSBG and SBG.

Tellurite glasses 75TeO₂-20ZnO-(4.6-x)La₂O₃-0.4Er₂O_3-xYb₂O₃ (x=0, 0.4, 0.8, 2.0, 3.2, 4.0) were prepared by conventional melt-quenching method. The effects of temperature (8-300K) and the ytterbium concentration on upconversion characteristics were investigated. When the Yb³⁺ concentration is 2mol%, the upconversion emission intensities around 545nm and 657nm present 6-fold and 4-fold enhancement, respectively, compared with Er³⁺-doped glass at room temperature. The green emission intensities around 530nm present monotonic increase with increasing temperature from 8K to 300K. The green emission intensities around 545nm increase with increasing temperature from 8K to 80K and reach the maximum at around 80K, then decrease with increasing temperature from 80K to 300K. The characteristics of the red emission intensity around 657nm are similar to the green emission intensity around 545nm. The effects of temperature and concentration of ytterbium on upconversion characteristics are analyzed by rate equations in details, which match well with the experiment results.

Neodymium-doped yttrium aluminum garnet (Nd:YAG) precursor powders were fabricated by co-precipitation method, using Al(NO₃)₃·9H₂O, Y(NO₃)₃·6H₂O, (NH₄)₂SO₄ and Nd(NO₃)₃ as raw materials, NH₄HCO₃ as precipitator, TEOS as sintering additive. After calcining the Nd:YAG precursor at 1200℃ for 5h, the well dispersive, spherical pure cubic YAG nano-powders with average particle size of about 100nm were obtained. Subsequently, calcined powders were molded by cold isostatic presses. Transparent ceramics of excellent transmission were obtained by sintering Nd:YAG green body at 1700-1800℃ for 10h in vacuum. The ceramic crystal grains with average size of about 15μm appear uniformity. There is no impurity and core in grain interface and inner-grain. No scattering center can be detected. The transmission of the sample with thickness of 1.5mm is 83.5% at the near infrared wavelength of 1064nm, which is very close to the theoretical value of Nd:YAG single crystal.

Nd:YSAG powders was prepared by using combustion method. After molding, calcining the Nd:YSAG green compact at 1750-1850℃ in H₂ atmosphere for 4-10h, the transparent Nd:YSAG ceramics were obtained. The optical properties of Nd:YSAG transparent ceramics were measured. The emission band of transparent Nd:YSAG ceramics is broadened and the fluorescence lifetime is prolonged as compared to Nd:YAG ceramics. Using LD as pumping source, and transparent Nd:YSAG ceramics as laser gain media, laser output is achieved. The maximum laser power is 0.36W and the slope efficient is 23.6%, the spectrum band of output laser is relatively broad.

Ce-doped Y₃Al₅O₁₂(YAG:Ce) nanophosphor was synthesized by the co-precipitation method. X-ray powder diffraction (XRD), Scanning electron microscope (SEM) were used to characterize the powders. The temperature dependences of luminescence and decay time of YAG:Ce nanophosphor were investigated in the temperature range of 80-400K. The luminescence intensity decreases with the increase of temperature, which is caused by the increase of the non-radiative relaxation rate. The decay of YAG:Ce contains two exponential terms, the long component presents decay of Ce³⁺ in the body, the short component reflects decay of Ce³⁺ on the surface. The long component decreases with the increase of temperature, while the short component shows intricate behavior, which results from effect of surface.

Samples with different In dopant concentrations were grown by Low Pressure Vertical Bridgman Method. Low temperature photoluminescence (PL) spectra, Deep Level Transient Spectroscope (DLTS) and high resistivity Hall test were used to study major defects in high resistivity In-doped CdZnTe crystal and its possible compensating mechanism. The PL spectra showed that in the In-doped CdZnTe samples of high resistivity, In dopants occupied Cd vacancies, which would exist in undoped CdZnTe crystal, forming shallow donor defect [In_Cd⁺], located at E_c-18meV, and the [In_Cd⁺] interacted with [V_Cd^2-] to form a complex defect [(In_Cd⁺-V_Cd^2-)^-] at E_v+163meV. The DLTS results showed that a deep level donor defect was found at 0.74eV below the conduction band, representing probably the energy level of antisite defect [Te_Cd]. The results indicated that the electrical properties of In-doped CdZnTe crystals were dominated by a comprehensive compensating consequence among In donor defects, deep level donor defect Te antisites, intrinsic acceptor defect Cd vacancies and other impurities acceptor defects.

Doughnuts like Cd(OH)₂ microstructures were synthesized by aqueous-phase method using carboxyl functionalized polyacrylamide (PAM-COOH) as crystal growth modifiers, which were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and the selected area electron diffraction (SAED). The influence of experimental conditions such as concentration of surfactant and reactants, temperature and reaction time on the structure and morphology of as-products were carried out in detail. Furthermore, possible formation mechanism of Cd(OH)₂ doughnuts in the presence of PAM-COOH was discussed. Results show that the obtained Cd(OH)₂ doughnuts with size of 1μm is composed of many single-crystal thin flakes with size of about 35nm. The temperature and concentration of reactants have effect on the morphology and size of the obtained product, but PAM-COOH plays a key role in the formation of Cd(OH)₂ doughnuts. Cubic phase CdO with doughnuts structure can be obtained by calcination of Cd(OH)₂ doughnuts at 350℃ for 3h.

Ammonia absorption/desorption properties of CaCl₂ and effects of the operation temperature, starting pressure and ball milling treatment were investigated. The post-2h milled sample can be fully ammoniated to form CaCl₂(NH₃)₈ within 15min under 20℃ and 0.55MPa, and the ammonia storage capacity is 55.1wt%, equivalent to be 9.72 wt% of hydrogen. NH₃ can be desorbed from CaCl₂(NH₃)₈ in the temperature range from 20℃ to 300℃ with three stages controlled by temperature and pressure. Six NH₃ molecules can be desorbed at ambient temperature and pressure. Combined with NH₃ decomposition catalyst, CaCl₂ may be one of promising ammonia-based hydrogen storage materials with high capacity. Further investigations indicate that higher operation temperature and starting pressure can improve the ammonia absorption kinetics of CaCl₂, and prolonging ball-milling time can decrease the operation temperature for ammonia desorption of CaCl₂(NH₃)₈ and improve its ammonia desorption kinetics.

Boron doped amorphous diamond (a-D:B) films, which possess a wide optical gap and good p-type semi-conductive electroconductibility, were prepared using filtered cathodic vacuum arc system, whose target source was highly pure graphite incorporated with boron element. The intrinsic layer and the n-type layer of amorphous silicon solar cells in a configuration of p-i-n were deposited using PECVD technology. The optical gap of the boron doped amorphous diamond films was characterized with a Lambda 950 UV-Vis photometer. The parameters of solar cells, such as open-circuit voltage, short-circuit current, fill factor and efficiency, were also measured. It shows that using the a-D:B films as the window layer of p-i-n structural amorphous silicon solar cell can increase the cell conversion efficiency by a roughly 10% relative improvement compared to the conventional amorphous silicon solar cell because of the enhancement of short wavelength response.

Hexagonal B-C-N compounds were successfully synthesized by using hydrogen-free 1,3,5-trichlorotriazine and boron tribromide as reactants and metal sodium as reluctant through a chemical reduction synthesis method at 450℃. The synthesized sample was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), selected area electron diffraction (SAED), electron energy loss spectroscope (EELS) and Fourier transformation infrared spectroscope (FTIR), respectively. The results indicate that the synthesized B-C-N compound is polycrystalline with hexagonal structure and its composition is B_0.5C_0.07N_0.43.

Titanium dioxide nanocrystal films were deposited on silicon substrates using pulsed laser deposition method. The influences of substrate temperature, oxygen partial pressure and the kinds of gas on the crystal structure of TiO₂ thin films were discussed. The optical properties of films were studied by means of transmission spectra in UV-visible range, Fourier transform infrared spectra and Raman spectra. The results show that the films are high c-axis-oriented anatase and (110) oriented rutile prepared at the substrate temperature of 750℃ under the oxygen and argon pressure of 5Pa, respectively. The field emission scanning electron microscopy images indicate that the TiO₂ films has a good smooth and hole-free surface which are composed of nanocrystal grains with about 35nm in diameter. And the optical properties tested show that the films are transparent in the visible range. From the transmission spectra in UV-visible range, the refractive index of the anatase and rutile TiO₂ films are determined to be about 2.3 and 2.5 at 550nm, respectively. And the optical band gaps are determined to be 3.2eV and 3.0eV for the anatase film and rutile film, respectively.

The TiO₂ nanofibres with the diameter of φ20-30nm and the length of micron-dimension were successfully synthesized by hydrothermal method. Their crystalline structure, morphology and chemical composition were characterized by the transmission electron microscope (TEM), X-ray diffraction patterns (XRD), infrared spectrum (IR), etc. The forming mechanism of the TiO₂
nanofibres and the effects of pH value in the process of washing on the nanofibres structure were investigated and analyzed, respectively. The results indicate that the forming mechanism of the TiO₂ nanofibres can be described as following: K₂Ti₆O₁₃ nanoparticles are initially formed in alkaline solution using anatase nanoparticles as raw materials, and then gradually
grown to nanofibres along a certain crystalline axis obeyed the dissolution-growth mechanism. The pH value of washing solution has a significant influence on the structure and composition of the products. The nanofibres of K₂Ti₆O₁₃, H₂Ti₃O₇ and TiO₂ can be obtained by the controlling of the pH value of washing solutions and heat-treatment temperature. The products, washed in solution with pH=7 and dried at 80℃, form the nanofibres of H₂Ti₃O₇, which is subsequently calcined to form TiO₂ nanofibres at 400℃.

A series of SiO₂/TiO₂ photocatalysts were successfully synthesized via a solvothermal method using titanium n-butoxide, tetraethoxysilane, acetic acid and water as raw materials. As-synthesized SiO₂/TiO₂ catalyst was characterized by XRD, Raman, BET, TEM, FT-IR and XPS and its phtocatalytic activity was evaluated by the degradation of methylene blue under UV light irradiation. The results show that there is strong interaction between TiO₂ and SiO₂, and Ti-O-Si bonds are formed in the SiO₂/TiO₂ catalysts. The obtained catalysts have large surface area and high crystalline anatase. Compared with pure TiO₂, the SiO₂/TiO₂ photocatalysts show better photocatalytic activity which can completely photodegrade MB after 65min UV light irridation.

A new nano-TiO₂ multiplex photocatalyst codoped with Eu²⁺ and Gd³⁺ was prepared by a modified acidic sol-gel process. TEM and XRD results demonstrate that as-produced samples are anatase structure, and the crystallite size has relationship
only with total doped Eu^2+/Gd³⁺ content and the minimum size appeares at 1% doped content. UV-Vis absorption spectra show
that Eu^3+/Gd³⁺ codoping can enhance the visible light response of the TiO₂. The photocatalyst activity of Eu^2+/Gd³⁺ codoped TiO₂ is evaluated by photodegradation of methyl orange in an aqueous solution under natural light irradiation, A synergetic effect is observed due to Eu^2+/Gd³⁺ codoping, and the optimal doping concentration for Gd³⁺ and Eu²⁺ are in the range from 0.1% to 1.0% and 0.5% to 1.5% respectively. The relationship and function between Eu²⁺, Gd³⁺ and TiO₂ are also discussed.