Due to its outstanding physical and electrical properties, graphene has become one of the hot research topics and frontiers in the fields of physics and semiconductor electronics. The physical and electrical properties of graphene were briefly introduced. A comprehensive review was presented to the current research activities concentrated on the epitaxial growth of graphene which could be the most promising strategy among the reported methods to meet the challenge for mass production of graphene with high quality. A systematical discussion was then presented to the epitaxial growth of graphene by using various substrates of SiC and metals. By the end of this article, an overview was made on the recent applications of graphene in opto/electronic devices, such as field-effect transistors, light emitting diodes, supercapacitors and lithium-ion batteries. It is accepted that not only growth of graphene with sizes from nanometer to centimeter could be achieved, but also the thicknesses with monolayer to a few layers could be successfully tailored via epitaxial growth of graphene on SiC/metal substrates. It is promised that the strategy of epitaxial growth could accomplish the mass production of graphene with high quality, low cost and compatibility to the conventional electronic process, which lays the significant foundations for the applications of graphenes in devices.

Carbon nanotubes (CNTs) were dispersed uniformly into mesophase pitch (MP) by the co-dispersion of ultrasonic and magnetic force stirring. Effects of CNTs on the supercritical foaming behaviors and mechanical performance of carbon foams were investigated. The results indicate that cell nuclei will form firstly at the CNT/MP interface in the supercritical foaming process, and then diffuse, aggregate, expanse and foam. CNTs can improve the homogenicity of pore structure due to the uniform dispersed CNT/MP interface. When MP is mixed with 3.5wt% CNTs, the compressive strength of graphitized foam increases from 3.2MPa to 4.7 MPa. In the graphitization process, the heat-stress different of carbon will decrease due to the high thermal conductivity of CNTs, leading to the decrease of the amount of microcracks. Meanwhile, the one-dimensional structure of CNTs reinforces the mechanical strength of pore walls and ligaments.

Using a naphthalene derived mesophase pitch as starting material, high oriented ribbon-shaped carbon fibers with smooth and flat surface were prepared by melt-spinning, oxidation stabilization as well as further carbonization and graphitization processes. The composition, morphologies and microstructure of the ribbon-shaped carbon fibers treated at various conditions were characterized by elemental analyses, IR spectroscopy, XRD, Raman spectroscope, scanning electron microscope and polarized-light microscope. The results show that the carboxyl, carbonyl and ether functional groups formed during the oxidizing stabilization process are removed by subsequent carbonization treatment. The width and thickness of the ribbon-shaped fibers at the transverse section decrease from 1.6mm and 18?m of pitch fiber to 1.2mm and 9?m of graphitized carbon fibers, respectively. The relative intensity of the diffraction peak at about 2? = 26? corresponding to (002) crystal plane of hexagonal graphite increases with the heat-treatment temperature increasing. This indicates that the crystal size of graphite in this carbon fibers also increases in this process. In comparison with the carbonized fibers, the carbon fibers after graphitization treatment display more perfect crystal orientation along the main surface of ribbon-shaped carbon fibers.

Porous and conductive diatomite composite materials were prepared via the calcination of the Sb-SnO₂-coated diatomite precursor derived from the co-precipitation route with diatomite as the substrate. Conductivity of the samples was influenced by the Sb-SnO₂ coating ratio. Calcination temperature had an impact on the crystal lattice parameters and grain sizes, hence altering the conductivity and resistivity of the composite materials. The samples were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectrometry (EDS), N₂ adsorption-desorption measurement (BET), and Fourier transform infrared spectrometry (FT-IR). The conductive performance of the samples was determined using a Four-Point Probe Meter apparatus. It is shown that the mesoporous (pore diameter = 6 nm) sample with n(Sn)/n(Sb)=8/1 and a Sb-SnO₂ coating ratio of 25.8wt% derived from calcination at 700℃ exhibited the lowest resistivity of 22 Ω·cm.

A series of composite of the negative temperature coefficient (NTC) powders of Mn_2.25-xNi_0.75Co_xO₄ (0.8≤x≤1.2) materials were prepared via solid-state method. The particle size of calcined powders, ceramics phase structure, morphology and electrical properties were characterized by laser particle size analyzer, XRD, SEM and electrical measurements, respectively. The results show that when the Mn_2.25-xNi_0.75Co_xO₄ ceramics sintered at 1130-1230℃, their characteristic parameters B25/50 value are found to be in the range of 3487K to 4455K and their electrical resistivities ρ25℃ are 1998 Ω·cm to 203617 Ω·cm. The B25/50 value and ρ25℃ first increases and then decreases as the Co content increases. This means that electrical resistivity and B value of Mn_2.25-xNi_0.75Co_xO₄ ceramics could be adjusted to the desired values and this ternary system can be considered as the advanced semi-conducting materials for NTC thermistor applications.

The oxygen-ionic conductor of La_9.33Si₆O₂₆-10wt% Zr_0.86Y_0.14O_1.92 composite material was prepared by using a modified co-precipitation method. X-ray diffraction, scanning electron microscope and complex impedance were adopted to investigate the phase component, microstructures and conductivities of the composite material, respectively. The results show that the average grain size of the as-calcined powder is 35 nm and the average particle size of the as-sintered composite ceramic is about 500 nm. The conductivities of the composite ceramic are higher than those of the single phase La_9.33Si₆O₂₆ and Zr_0.86Y_0.14O_1.92 ceramic at the temperatures from 300℃ to 700℃. The conductivity of the composite ceramic is one order in magnitude higher than that of polycrystalline La_9.33Si₆O₂₆ at 700℃. The conduction mechanism of the composite material is discussed by the analysis of impedance spectra and electric modulus spectra.

La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) based composite anode with SDC interlayer for solid oxide electrolysis cell was prepared by screen printing technique. Electrochemical performance of the electrode at 800℃ was examined by linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) methods. The result of EIS analysis suggestes that the oxidation kinetics of O^2- to O₂ is controlled by three electrode procedures, including charge transfer at the electrode/interlayer interface, charge transfer at the interlayer/electrolyte interface and oxygen desorption/diffusion. Scanning electron microscope analysis shows that composite anode layer, SDC interlayer and the electrolyte are integrated and well-combined. In terms of anode polarization, LSCF based material exhibites a better application perspective rather than traditional LSM-YSZ composite material for SOEC anode.

0.7BiFeO₃-0.3PbTiO₃ (BFPT7030) thin films were prepared on LaNiO3/SiO2/Si substrates by Sol-Gel process. The films were annealed by rapid thermal annealing technique (RTA) and conventional thermal annealing (CTA) technique, respectively. XRD patterns of the films indicate that BFPT7030 films annealed by RTA show a single perovskite phase and better crystallinity as suggested by stronger and sharper XRD peaks. SEM observations demonstrate that BFPT7030 films annealed by RTA are fully crystallized, but films annealed by CTA have a dense morphology and exhibits small grain size especially for film heated at rate of 2℃/min. Enhanced ferroelectric properties are observed in the films annealed by RTA. The film heated at rate of 20℃/s exhibits a remnant polarization of 22 μC/cm² with a low coercive field of 70 kV/cm. And lower leakage current density is observed in BFPT7030 films annealed by RTA as compared to BFPT7030 films annealed by CTA. XPS analyses demonstrate that the oxidation state of Fe ions is the coexistence of both Fe³⁺ and Fe²⁺ in the BFPT7030 films annealed by RTA and CTA, but less fluctuation of Fe³⁺ to Fe²⁺ exists in the BFPT7030 films annealed by CTA.

CaCu₃Ti₄O₁₂ (CCTO) is one typical giant dielectric material with large ε' value in the order of 104, however, origin of giant dielectric permittivity in it is still controversial so far. In order to explore its possible origin, the dielectric properties and complex impedance of CCTO ceramics prepared via solid-state reaction method were investigated. Within the frequency range of 40 Hz-100 MHz, only one Debye-type relaxation around 1 MHz is observed at room temperature, while high-temperature dielectric dispersion shows two Debye-type relaxations below 1 kHz and around 1 MHz, respectively. The same sample surface-polished with Ag-paint electrodes and sputtered Au electrodes is measured at high temperature, respectively. It is revealed that the dielectric relaxation in the low frequency range changes significantly with the type of electrodes, while the dielectric relaxation in the high frequency range is independent of the type of electrodes, but exists closely relationship with the microstructure of samples. The two dielectric relaxations are thus suggested to originate from an electrode polarization effect and an internal barrier layer capacitance effect associated with insulating grain boundaries and semiconducting grains, respectively.

The nickel-alumina composite coatings were fabricated by the axial plasma spraying method. The effects of the different content of Ni on the microscopic structure, mechanical and dielectric properties of the composite coatings were investigated. The results indicate that with the increase of nickel content, the distribution of Ni particles changes from separated to large but finite interconnected clusters. The relative density and the bending strength decrease gradually, which is attributed to thermal expansion mismatch and non-wettability between alumina and nickel. The increase in the fracture toughness is caused by the Ni particles’ extension and deflection of the crack. The complex dielectric constant measurements indicate that the real part shows an increase and then decline trend with the Ni content in the frequency of 8.2-12.4GHz, while the imaginary part continues increasing. This is ascribed to the bridge structure of Ni particles.

The composite scaffolds (MBG/DB) were prepared successfully through immersing the mesoporous bioactive glass powders into the demineralized bones. The bovine cancellous bone, demineralized bone, composite scaffold were investigated and characterized by FTIR, SEM, XRD and universal electromechanical testing machine. The results show that the compressive strength of the demineralized bones is about (1.10±0.31)MPa, the porosity is about 71% and the pore size is in the range from 200 to 600μm. However, the porosity and the compressive strength of the composite scaffolds are decreased to 40% and increase markedly to (8.49±2.14)MPa, respectively. Meanwhile, the composite scaffolds show good bioactivity in vitro.

To explore and develop scaffold for bone regeneration or tissue engineering with the capacity of controlled drug delivery, the feasibility of hydroxyapatite/polyurethane (HA/PU) scaffold containing drug-loaded microspheres for controlled drug delivery system was demonstrated. Ciprofloxacin hydrochlorid as a model drug was encapsulated in ethyl cellulose (EC) microspheres, which were subsequently incorporated into HA/PU composite scaffold to generate an antibiotic drug delivery system. The results show that EC microspheres are uniformly distributed in the HA/PU scaffold matrix and display no significant effect on the pore structure of the scaffold. Compared with incorporating ciprofloxacin hydrochlorid into scaffolds directly, embedding microspheres into scaffolds significantly reduces the initial burst drug release and extends the release time of drug delivery. In vitro drug delivery tests and antibacterial activity tests prove that drug-loaded microsphere/scaffold system has good drug delivery properties and effective antibacterial properties. These results suggest that the novel drug-loaded microsphere/ scaffold composites developed in this study is a good candidate scaffold with the function of bone repair and infection treatment for bone tissue engineering.

Morphology-controlled niobium oxide nanorods array were successfully prepared in a mixed NH₄F and H₂O₂ solution by using niobium powder as the starting materials via hydrothermal method. The morphology and composition of niobium oxide film were characterized by X-ray diffraction patterns(XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), respectively. The reaction time and hydrothermal temperature and concentration of NH₄F, which affect the final composition and morphology of niobium oxide films, were also investigated in details. The results show that niobium oxide crystal have a strong anisotropy growth in the presence of NH₄F and H₂O₂, which guides the oriented growth of hexagonal nanorods array on the niobium powder surface. The concentration of NH4F play great roles in the formation of the final products, the morphological of niobium oxide film is transformed from polyhedron granule to circular nanorods array and aggregated nanoparticles with the increase of NH₄F concentration. Niobium oxide nanorods arrays can be obtained at Nb substrate after hythermal reaction at 150℃ for 10h with adding 0.5g NH₄F. A formation mechanism is also proposed.

Silica modified by γ-glycidyloxypropyltrimethoxysilane was used as precursor to prepare amphiphilic silica nanocomposites by quaterisation. The structure of the as-prepared products was characterized by means of fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscope (XPS). Transmission electron microscopie (TEM) was used to characterize the morphology of the nanocomposites. The results showed that the content of the organic components at the silica surface calculated from TGA data was 11wt%. TEM provided direct evidence for the well amphiphilicity, and the same conclusion was confirmed by the photographs of the pristine SiO₂ and surface-modified SiO₂ nanocomposites in water/toluene mixed layers.

Micrometer SiO₂ microspheres were prepared by two-step catalytic Sol-Gel method with tetraethoxysilane (TEOS) as starting material and N,N-Dimethylformamide (DMF) as template. The effects of some factors on the diameter and particle size distribution of the SiO₂ microspheres were discussed, such as H₂O quantity and ethanol quantity during the first catalytic process, the electrolyte concentration and stirring speed during the secondary catalytic process. SiO₂ microspheres were characterized by SEM, Zetasizer, BET measurements and microscope-particle image analysis system. Results show that SiO2 microspheres are mostly regular-ball with no particle agglomeration. The mean particle size (D50) is 8.9μm, and the particle size distribution follows typical Gaussian distribution. The specific surface area is 546.67m²/g, and pore volume is 0.7142m³/g, with a narrow pore size varied from 2nm to 8nm. Also the particle size increases with water quantity, ethanol quantity and NaCl concentration increaing, but decreases with stirring speed acceleration.

Porous anorthite/mullite composite ceramics with different mullite contents were fabricated by foam-gelcasting method, using CaCO₃, SiO₂, α-Al₂O₃ as raw materials. Effects of mullite content on bulk density, porosity, compressive strength, thermal conductivity and microstructure of the porous composite ceramics were researched. Mullite content has great effect on the apparent porosity of the porous anorthite/mullite composite ceramics. As a result of the appearance of liquid phase in the sintering, the sample shrunk, which is the main reason for the porosity decrease. Compressive strength and thermal conductivity increase with the mullite content under the condition of the similar porosity. Dense pore wall and rod-like mullite grain are benefit for compressive strength of porous   anorthite/mullite composite ceramics. The apparent porosity of the prepared porous anorthite/mullite composite ceramics is in the range of 60.8%-75.2%, the compressive strength is between 12.94 MPa and 36.95 MPa, and the thermal conductivity is in the range of 0.30-1.33 W/(m·K).

Boron carbide (B4C) powder was synthesized by solid state reaction of hexagonal boron nitride with carbon black (or graphite). The phase assemblages of synthesized powders were influenced by carbon source, atmosphere and temperature. Boron carbide powder with an average particle size of about 100 nm was obtained using carbon black as the carbon source at 1900℃ for 5 h in vacuum. The relative density of the sintered sample (2000℃/30 MPa/1 h) derived from the synthesized powder reached 97.9%, while that prepared from the commercial powder was 93.1%. The better sinterability of the synthesized powder than the commercial one can be attributed to the finer particle size, lower oxygen content and the twin structure of the powder.

In order to reduce the toxicity of gelcasting with traditional AM/MBAM Gel system and Prepare high properties green bodies and ceramics. Gelation process of low-toxic DMAA /MBAM system as well as the effect of pH and NH4PMAA on rheological behaviors of slurries were studied. The perfect green bodies and ceramics were prepared using high solid loading slurries with low viscosity and low-toxicity. The solid loading of slurries can be up to 56vol%. The green bodies are surface-smooth without cracking or exfoliation and their bending strength can reach 30MPa. The pore size distribution of the green bodies is single peaked. The mean bending strength of sintered ceramics is 960MPa and the fracture toughness can reach 17.3MPa^.m^1/2. The zirconia ceramics have good homogeneity and well dense structure, consisting of more tetragonal ZrO₂ phase.

With self-assembled monolayer (SAM) as template, cubic cuprous-oxide (Cu₂O) crystals with preferred orientation are obtained via simple and effective electrochemical redox process. Micro-region X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the as-grown Cu₂O crystals. Besides uniform morphology and crystal size, the micro-crystals take preferred orientation that is strongly influences by the pre-modified SAM on substrate. The experiments indicate that the SAM not only acts as the growing template for the crystals, but also strongly affects the electrochemical redox process. To explore its sensing properties, the Cu₂O crystals were grown onto a micro-cantilever to detect DMMP (dimethyl methylphosphonate) vapor. The sensing mechanism is complexation of phosphonyl group with Cu(I) that generates surface-stress at the cantilever surface. Tens of ppb DMMP vapor is reproducibly detected.

The polycrystalline rare-earth hexaborides (Ba_xGd_1-x)B₆ (x = 0, 0.2, 0.4, 0.8) were prepared by the reactive spark plasma sintering (SPS) method using mixed powder of BaH₂, GdH₂ and B. The effects of Ba doping content on the crystal structure, the grain orientation and the thermionic emission properties of the GdB₆ were investigated by X-ray diffraction, electron backscattered diffraction and emission current measurements. It is found that all the sintered samples exhibit high densification (> 97%) and high value of Vickers hardness (2070 kg/mm²). The maximum thermionic emission current density of GdB₆ is 11 A/cm² at a cathode temperature of 1873 K, which is much higher than that of traditional method. With the increase of Ba content, the thermionic emission current density decreases from 11 A/cm² to 2.25 A/cm² at 1873 K.