Diamond films have been paid much attention in high frequency and high output power field, especially in field effect transistors (FET) with its outstanding electrical properties in the last two decades. For optimum electronics performance, quality of electronic films, good contacts and forming semiconductors are key techniques to make FETs. How to reduce gate length and various parasitic parameters and improve withstand voltage and heat-sinking capability determines whether FETs are of high-performance. The breakouts of key techniques, research progress and related hot spots of diamond films for high frequency and high output power FETs are reviewed. Mechanisms proposed to explain electrical conductivity of H-terminated diamonds are also presented.

Different shapes of nano titanium dioxide including sphere, rod and irregular-shaped polyhedron were prepared by solvothermal process at heating rates of 240℃/10min, 90℃/10min, 40℃/10min and 20℃/10min using tetrabutyl titanate as Ti source, oleic acid as solvent, dodecylamine as auxiliary agent. TEM, HRTEM and XRD were adopted to characterize the phase composition morphology and phase structure of the final products. The   micro-morphology and growth mechanisms of the titanium dioxide nanocrystals prepared at different heating rates were studied based on the TEM, HRTEM and XRD analyses．The results show that spherical, rod-like, and irregular polyhedral points of titanium dioxide nanocrystals could be synthesized by strictly controlling the heating rate. The growth rate of along the (001) direction of nanocrystal shows a first upward and then downward trend with the decline of the heating rate.

TiO₂/SiO₂ composite aerogels with different silicon contents were prepared by Sol-Gel method. The microstructure of TiO₂/SiO₂ composite aerogels was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), X-ray photoelectron spectroscope (XPS) and N₂ adsorption-desorption, the photocatalytic activity was evaluated by means of photocatalytic degradation of methyl orange under UV irradiation. The effects of silicon content on microstructure and photocatalytic activity were investigated. The results show that Ti-O-Ti bonds, Si-O-Si bonds and Ti-O-Si bonds all form in TiO₂/SiO₂ composite aerogels, which make composite aerogels have smaller crystal size, higher specific surface area and better thermal stability. As the silicon content increases, the specific surface area increases, however the anatase grain size, the anatase content and the average pore diameter reduce. At higher silicon content level, the photocatalytic activity of composite aerogels for methyl orange is improved initially, then decreases with the increase of silicon content. Proper silicon content can refine the structure and improve photocatalytic activity of TiO₂/SiO₂ composite aerogels dramatically, and the optimal silicon content is about 9wt%.

Five groups of TiO₂ nanotube array films with different inner diameters and five groups with different tube lengths were fabricated on titanium by anodization. Morphology was analyzed by scanning electron microscope. The photocatalytic activity of the TiO₂ nanotube films crystallized into anatase, was evaluated by the decolorization of methyl orange in aqueous solution under UV light irradiation. The effects of the nanotube diameter and length on the photocatalytic activity were investigated. The reusability of photocatalyst was evaluated through repeated photocatalytic reaction experiment. Results suggest that the TiO₂ nanotube films with the diameter of 100nm exhibit the best photocatalytic activity to the degradation of methyl orange, and the length of nanotube has little effect on the photocatalytic activity. Repeated photocatalytic reaction experiment shows that the TiO₂ nanotube films have excellent resuability as photocatalyst.

Fe-doped TiO₂ (Fe-TiO₂) and N, Fe co-doped TiO₂ (N-Fe-TiO₂) nanomaterials were synthesized by solid-state reaction, respectively. The textural properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet visible light spectroscope (UV-Vis), X-ray photoelectron spectroscope (XPS). The components of the samples were determined by atomic absorption spectrum (AAS) and automatic elemental analyzer. Moreover, the photodegradation properties of quinoline irradiated under visible light on the materials were investigated. The results show that N atoms as N^3- states are incorporated into the lattice of TiO₂, and Fe³⁺ ions occupy the sites of Ti⁴⁺ by isomorphous replacement in the spheric shape N-Fe-TiO₂ nanomaterials. The UV-Vis absorption onset of the N-Fe-TiO₂ samples extends well into the visible region at 600 nm. Furthermore, an increase of the initial ratio of N₂H₄·H₂O to FeCl₃·6H₂O enhances the phase transformation of N-Fe-TiO₂ catalysts. At 25℃, pH=6.5, the rule of pseudo-first-order reaction and excellent photocatalytic activity on the N-Fe-TiO₂ catalysts are found in the process of photodegradation of quinoline. However, quinoline can not be degradated by pure TiO₂ under visible light irradiation. The reaction rate constant of N-Fe-TiO₂ (n(N₂H₄.H₂O): n(FeCl₃.6H₂O)=1:9) catalyst is higher than that of pure TiO₂ powder.

Visible light response lanthanum-doped TiO₂ film was prepared by Sol–Gel method using Ti(OBu)₄ and La(NO)₃·6H₂O as raw materials. XPS, FTIR, XRD, N2(77K) adsorption, SEM and DRS were used for catalyst characterization. Gaseous toluene removal was used for photocatalytic activity test. The results show that La dopant can induce visible light activity. The sample of 2.8-La/TiO₂-500 exhibites the highest activity, which can remove toluene of initial concentration 6110.18mg/m³ completely within 60min. La³⁺ disperses onto TiO₂ as the form of La₂O₃ and partly as the form of Ti-O-La bond. La dopant can inhibit phase transformation, enhance phase transformation temperature and is also beneficial to gain smaller particle size and large surface area of TiO₂. Compared with pure TiO₂ film, La dopant can also inhibit the generation of air-pores and the surface of La/TiO₂ film is more dense and smooth. Electrons transfer of f level of La and the destortion of TiO₂ lattice is the main reason for the enhancement of visible-light activity.

ZnO/AgNbO₃ hetero-junction photocatalysts were prepared by impregnation method. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), scan electron microscope (SEM) and UV-Vis diffusion reflectance spectra (DRS). The results indicated that Zn dopant did not change the crystal structures of AgNbO₃. With increasing Zn content and calcination temperature, the ZnO phase formed in the ZnO/AgNO₃. XPS analysis indicated that Zn²⁺ existed as ZnO. The DRS spectra showed that Zn dopant enhanced the ability of visible light absorption of the ZnO/AgNbO₃ samples. The photocatalysts doping with ZnO exhibited the enhanced photocatalytic activities for degradation of methylene blue (MB) under visible light and UV light irradiation. The highest efficiency was obtained when the sample calcined at 300℃ with 3 wt% Zn content under UV light irradiation. The mechanism of improving photocatalytic activity was also discussed.

The [Ca₂₄Al₂₈O₆₄]⁴⁺·4O^-(C12A7-O^-) particle was firstly investigated its antibacterial activity against bacteria E. Coli in aqueous solution and phosphate buffered saline (PBS). The C12A7-O^- particles were synthesized by gas-solid reaction method with CaCO₃ and γ-Al₂O₃ in a molar ratio of 12:7. The structure change of the C12A7-O^- particles was measured by X-ray diffraction (XRD) and electron spin resonance (ESR) after antibacterial test. The results show that the structure of the C12A7-O^- particles is completely changed into the structure of (CaO)₃Al₂O₃·6H₂O and Al(OH)₃. In the C12A7-O^- solution (1 mg/mL), the concentration of atomic oxygen anion (O^-) in the solution is 4×10¹⁶ cm^-3. In the antibacterial test with the particle concentration of 3 mg/mL in aqueous solution, the bacteria concentration in decreased by 99.98% in 1 h from the original concentration of 10⁵ cfu/mL. When the particle concentration is 1 mg/mL in PBS, the pH is 7.4 and the pH effect of the solution could be neglected, but the bacteria concentration still deduces to 3.7×10³ cfu/mL from the original concentration in 24 h. In briefly, O^- is the main factor in the antibacterial test in the C12A7-O^- PBS solution with the neutral pH environment.

Single-crystalline magnesium borate nanorods were fabricated by solvothermal method at the supercritical conditions. This reaction condition enabled the formation of magnesium borate with one dimensional nanostructure without the involvement of surfactants. The microstructures of as-synthesized products prepared at different reaction stages were characterized by X-ray diffraction. The results show that Mg₂B₂O₅ structure is obtained through an intermediate transition from Mg(OH)₂ to MgBO₂(OH), and then from MgBO₂(OH) to Mg₂B₂O₅. The morphology of the products at corresponding stages were observed by scanning electron microscope(SEM), showing that the formation process of Mg₂B₂O₅ nanorods was from flake-like to short columnar and then to rod. The result suggests that the formation of Mg₂B₂O₅ nanorods follow a process from nucleation → dissolution → anisotropic growing → recrystallization.

CsBr:Eu²⁺ powders were prepared by solid-state reaction. The photostimulated luminescence (PSL) spectra, the differential absorption spectra (DAS) and PSL lifetime spectra were systematically investigated. The results reveal the annealing process can increase the PSL intensity and decrease the PSL lifetime. The relationship between the annealing atmosphere and PSL properties were discussed in detail, and the results reveal that substitutional oxygen ions O_s^- (S: substitute, O^- substitute for Br^-) and interstitial hydrogen atoms H_i⁰ are formed in the annealing process. All of O_s^-, H_i⁰ and H_2i⁰ are electron trap centers, which are closely related to the formation of hole traps centers.

YVO₄ and Eu³⁺-doped YVO₄ nanoparticles were synthesized via hydrothermal method, using Y(NO₃)₃·6H₂O, Eu₂O₃, NH₄VO₃, and Na₃C₆H₅O₇·2H₂O as starting materials. The structure and morphology of the resulting products were characterized by XRD, FESEM, TEM, HRTEM and SAED, while the spectra properties of the products were investigated by FT-IR spectrometer and fluorescence spectrometer. The results indicate that  as-prepared products are crystallized in pure body centered tetragonal YVO₄ phase with uniform caky morphologies and the sizes of the samples are estimated to be around 500 nm. XRD patterns of the as-fabricated Eu³⁺-doped YVO₄ nanoparticles show that Eu³⁺ is doped at Y³⁺ sites in YVO₄ crystal. There is no emission peak of VO₄^3- from fluorescence spectrum of YVO₄: Eu nanoparticles, which indicates that YVO₄ is a very attractive luminescent host. Hydrothermal method is convenient and easy, and the as-prepared YVO₄:Eu nanoparticles show strong and stable fluorescent intensity. It can be expected that the YVO₄:Eu nanoparticles have potential application in electroluminescent devices, integrated optics or biological labels.

The colossal magnetoresistive and electric pulse induced resistive switching properties of La_1-xCa_xMnO₃ (x=0.3, 0.5) polycrystalline at high magnetic field and low temperature were studied. The difference of colossal magnetoresistive and electric pulse induced resistive switching was analyzed. The EPIR effect of La_1-xCa_xMnO₃ (LCMO)(x=0.3, 0.5) polycrystalline also exist at high magnetic field and low temperature. The ratio of high resistance state and low resistance state has no obviously change with varying temperature and magnetic field. The CMR property comes from double exchange and Jahn-Teller effect. Increasing the magnetization by applying an external field would increase the charge mobility of ferromagnetic phase and then decrease the resistance via the double exchange mechanism. Ions motion driven by electric pulses is presented for explaining the resistance switching. The motion of oxygen would change the hole density of local regions. The change of hole density would still exist at low temperature and modulate the low temperature magnetic configuration of LCMO.

By using pulsed laser deposition method, nanostructured BaTiO₃ ferroelectric films (with a thickness of 25 nm) were grown on Si substrates and coated by nanoporous alumina membranes (NAMs) with an average pore size of 25 nm. Metal Pt nanowires were embedded in NAMs as a part of the bottom electrode. The dielectric and ferroelectric properties, and microstructure of the nanostructured BaTiO₃ films were characterized. The results show that the dielectric constant of the BaTiO₃ nanofilms is decreased slowly from 196 to 190 as the increase of measured frequency from 10³ Hz to 10⁶ Hz, and their dielectric loss is increased slowly from 0.005 to 0.007 in the low frequency range from 10³ Hz to 10⁵ Hz, whereas quickly increased up to 0.013 at high frequencies over 10⁵ Hz. The remanent polarization and the coercive field of the BaTiO₃ nanofilms are 5 uC/cm² and 680 kV/cm, respectively. Cross-sectional (scanning) transmission electron microscope (TEM) images demonstrate that the BaTiO₃ nanofilms contact directly with the Pt nanowires, and the interface between them has some degree of waviness. Suitable post-annealing temperature is the critical processing parameter of fabricating nanostructured ferroelectric films as considering a trade-off between the ordered degree of metal nanowires within NAMs and the crystallinity of ferroelectric nanofilms.

To elevate the productivity of high critical current YBCO superconducting films by TFA-MOD processing, traditional trifluoroacetate (TFA) was replaced by acrylic acetate partially. Since the fluorine content in precursor solution was decreased, the ramping rate in decomposition process reached 300℃/h. Meanwhile the atmosphere was also adjusted to avoid the fatal effect of diethanolamine (DEA), and to increase thickness of YBCO film. By increasing the maximum of DEA addition to 0.75g/5mL, the thickness of film reaches 1μm. While some a-axis grains dispersed on the film surface are probably ascribed to the rise of thickness, the YBCO film has good interior microstructures overall. As a result, the highest critical current density is 3.5MA/cm² and the critical temperature is 90K as well.

A new TiCN/Al composite foil for capacitor negative applications was prepared by multi-arc ion plating method. The effects of cooling process and flow ratio of C₂H₂ to N₂ for deposition on specific capacitance were investigated. The polarization curves were measured for TiCN/Al composite foil and traditional etching aluminum foil and their corrosion resistance were compared and discussed. Specific capacitance of TiCN/Al composite foil obtained is as high as 1600μF/cm² which is over two times higher than that of the aluminum foil prepared using the traditional etching process. The TiCN/Al composite foil shows a wide range of stable passivation zone in the capacitor electrolyte solution and its corrosion resistance is significantly higher than that of the aluminum foil fabricated by the traditional etching process.

Sr-doped LaFeO₃ (LSF) based composite anodes of solid oxide electrolysis cell (SOEC) were prepared by screen printing and ion impregnating respectively. XRD, TEM and SEM were used to analyze the phases and microstructures of the powders and the composites. In addition, anodic polarization tests and electrochemical impedance spectra (EIS) analysis were used to study their electrochemical properties at 800℃ which was the working temperature of SOEC. The results show that the grain size of LSF20 (La_0.8Sr_0.2FeO_3-δ) powder prepared by coprecipitation-azeotropic distillation (CP-AD) method is in the range of 20-30nm. The LSF powders spread on the surface of yttria-stabilized zirconia (YSZ) ceramic skeleton. The anodic polarization current densities of LSF20-YSZ composite anodes prepared by ion impregnating method are 0.38-0.49A/cm² under 0.1V overpotential at 800℃, which is almost 2-2.5 times as much as that of screen printing process.

Li₄Ti₅O₁₂ is the most potential candidate anode material of lithium-ion power battery for hybrid electric vehicles. In order to improve its rate performance, through doping and heat treatment on Li₄Ti₅O₁₂ with urea as nitrogen source, TiN high electrical conducting layer was prepared by in-situ selfgrowing on the surface of Li₄Ti₅O₁₂ particles. The crystalline structure, morphology, composition and electrochemical properties were studied by XRD, SEM, TEM, EDS, Raman spectra and half cell charge/discharge performance testing. The results show that nitridated Li₄Ti₅O₁₂ powers have the same diffraction peak positions of the spinel structure of Li₄Ti₅O₁₂ with pristine Li₄Ti₅O₁₂, and it is observed the presence of nitrogen and Raman feature vibration bands of TiN in in-situ selfgrowing a homogeneously layer on the surface of Li₄Ti₅O₁₂ particles. The first discharge specific capacity of nitridated Li₄Ti₅O₁₂ samples slightly decreases than pristine Li₄Ti₅O₁₂ samples at 0.1C rate. However, the discharge specific capacity of the nitridated Li₄Ti₅O₁₂ samples is 1.6 times higher than that of the pristine Li₄Ti₅O₁₂ samples at 3C rate charge and discharge, and the capacity loss of them is only 3% at 0.1C rate after 100 cycle numbers. The results illuminate the nitridated Li₄Ti₅O₁₂ samples have good electrochemical rate performances and cycling behavior.

High thermal conductive mesophase pitch-based graphite fiber was prepared through melt spinning, stabilization, carbonization and graphitization. It was proved that the spinning process was crucial for the degree of preferred orientation of mesophase molecular along the fiber axis. Effect of spinneret structure with rectangular section and spinning temperature on the preferred orientation degree and conductivity properties of MPGF were investigated. The experimental results demonstrate that larger aspect ratio of spinneret section facilitate higher preferred orientation degree of molecular and conductivity. At 9:1 of the aspect ratio and 305℃ of spinning temperature, the orientation degree of graphite crystal with respect to fiber axis and thermal conductivity of MPGF reached 97.8% and 894 W/(m·K), respectively. Furthermore, the mesophase pitch still?exhibite good spinnability. With increasing the aspect ratio of rectangular section of spinneret, larger shear action leads to higher internal stress of fiber, and resultes in poor spinning stability.

Axial thermodynamic performance of braid carbon/carbon (C/C) composites and needle C/C composites is compared. Braid C/C composites comprises the radial rod preform composite, the axial rod preform composite and the fine woven punctured preform composite. Needle C/C composites consist of the whole felt preform composites and the carbon clothes/felt layer needling preform composites. The bulk density of the whole felt preform approximates 0.2g/cm³, and the carbon clothes/felt layer needling preform is about 0.45g/cm³. The density of needle preform is less than that of braid perform, which is up to 0.70g/cm³. Axial fiber content of braid preform is more than or equal to 19%, while that of needle preform is only 5%. The axial tensile strength and thermal expansion coefficient are related to the structure of preform and axial fiber content. The average axial tensile strength of braid C/C composites is ≥40MPa, and while the needle C/C composites is around 10MPa. The axial thermal expansion coefficient of the axial rod preform, the fine woven punctured preform, the whole felt preform and the carbon clothes/felt layer needle preform C/C composites is comparative in the range of RT -800℃.

A hip joint simulator was employed to predict the clinical wear behavior with testing conditions of a cross-path motion, a constant load and a lubricant of serum. The worn surface and the wear particles generated were analyzed by scanning electron microscope, energy dispersive spectroscope and laser particle size analyzer. The results show that the biomedical C/C composites for artificial hip joints have different wear features according to the carbon fibre orientation. Their wear particles have four kinds of morphologies with a size ranging from submicron to tens of micrometers. The wear mechanisms are mainly micro-cutting and abrasive wear.

The aim of the present work was to prepare Ti₃SiC₂-SiC composite by using liquid silicon infiltration (LSI) from TiC/C preform. XRD, SEM and EDS were used to identify the formed phases and analyze the microstructures of the obtained composites. The results show that the composites are made of Ti₃SiC₂ and small SiC. The surface morphologies of Ti₃SiC₂ exhibit plate-like structure with the grain size of 3-10um. The hardness of S1550-1, S1550-3 and S1550-4 is 6.8GPa, 7.1GPa and 7.8GPa for a load of 10kg, respectively. Their density is in the range of 3.55-3.96g/cm³. All the experimental results prove that the novel in situ synthesis route of Ti₃SiC₂-SiC composite by LSI is feasible.