Infrared optical material is a foundation for the application of infrared technologies. Long-wavelength infrared optical materials, which can be used suitably in the infrared region from 8μm to 12μm, have important application prospect. Several kinds of long-wave infrared optical materials currently available are introduced in this paper. The fabrication techniques and the research status of these materials are reviewed. The problems related to their fabrication and applications are also discussed. Finally, it is recommended that the progress trends in long-wavelength infrared optical materials will be focused on the design and preparation of composite infrared optical materials, the growth technology of large-size II-VI compounds single crystals, the technology of protecting films used for alkali halides compounds crystals and the development of new chalcogenide glass.

Anodization of Ti using ethylene glycol containing 0.5wt％ NH₄F as electrolyte resulted in ordered arrays of TiO₂ nanotube with a smooth surface. Electrochemical anodization was carried out at room temperature. The microstructures and morphologies of the TiO₂ nanotube were nvestigated by scanning electron microscope (SEM), X-ray diffraction (XRD). A series of studies were carried out to investigate the properties of TiO₂ nanotubes (anatase) for lithium anode materials and for the materials of photocatalyzing degradation of aqueous methyl orange. The results show that high density, well ordered and uniform TiO₂ nanotube arrays are fabricated. TiO₂ nanotube shows a comparatively reversible reaction when it is used for lithium ion battery by CV measurement. Adding H₂O₂ into the solution can improve the photocatalysis of TiO₂ nanotube.

The photocatalyst of TiO₂ loaded with strontium ferrite were synthesized via sol-gel technology and characterized by X-ray powder diffraction (XRD), electron microscope (TEM), UV-Vis diffused
reflectance spectroscope (DRS) and vibrating sample magnetometer(VSM). The photocatalytic activities of the samples were evaluated by decolorization of methylene blue(MB) under UV irradiation. The results indicate that the TiO₂ loaded strontium ferrite photocatalyst is responsive to the visible light region according to DRS analysis. It is also found that the composite has good magnetic property. About 99.1％ MB can be removed at the catalyst dosage of 1.5g/L under UV irradiation for 300 min, when the catalyst is loaded with 20％ strontium ferrite.

TiO₂-mounted diatomite photocatalysts were prepared by a sol-gel method with diatomite support, a kind of natural biological diatomaceous silica earth. SEM observation shows that TiO₂ is well mounted on the surface of diatomite as films and some particles. Ti ₂-mounted diatomite decomposes efficiently methy1ene blue (MB) under UV irradiation. Within 36h irradiation, about 90％ MB is decomposed by TiO₂/diatomite photocatalyst. After 48h irradiation, MB is decomposed almost completely (about 98％). However only 35％ MB is decomposed by pure diatomite after 48h irradiation. With the increasing heat-treatment temperatures, the photocatalytic activity of the TiO₂/diatomite is increased with the formed anatase type of TiO₂ increasing, but decreased with rutile type of TiO₂ formed at 700℃ and 900℃. Adding H₂O₂ in MB solution can improve the efficiency of the TiO₂-mounted diatomite photocatalysts greatly.

The hydrothermal synthesis of polymorphic titania crystals and their structural evolution from potassium titanates, K₂Ti₆O₁₃, K₂ Ti₄O₉ and K₂Ti₈O₁₇ whiskers, were studied systematically. Dispersed, regular twinning rutile TiO₂ was firstly generated by hydrothermally treating K₂ Ti₆O₁₃ whisker in an acid medium. The crystal phase and morphologies varied with different reaction temperatures and time in diverse mediums were investigated using XRD, SEM and TEM. The results indicate that the weak-binding crystallographic planes are the key factors of the crystal transformation in the hydrothermal system. The transformation from K₂ Ti₆O₁₃ to the twinning rutile is achieved via rearranging structural units on the {100} or{ 201} plane.

MgCuZn ferrites were fabricated by the traditional oxide-sintering method to explore the way to improve their sintering characteristics and soft magnetic properties. Effect of Bi and Mo co-doping on magnetic performances of MgCuZn ferrites with lower sintering temperature and high initial permeability was discussed. Results show that the density is larger than 4.75g/cm³ for the MgCoZn ferrite sintered at 1020℃with moderate quantity of Bi and Mo doping(0.6wt％ and 0.1wt％, respectively), initial permeability is as large as 1240 and quality factor is as high as 33.8 at 100kHz, respectively. Thus, MgCuZn ferrite may be used in multilayer chip inductor by appropriate constituents, doping and preparing technology.

Zn_1-xCr_xO diluted magnetic semiconductors were synthesized by hydrothermal method at 260℃ for about 28h with different concentrations of Cr (x=0.1, 0.15, 0.2 and 0.25), NaOH with concentration of 3mol/L were used as the mineralizer. X-ray diffraction patterns indicate
that as-prepared Cr-alloyed ZnO has the wurtzite structure with Zn²⁺ partially substituted by Cr₃₊ , and the average crystallite size of Zn_1-xCr_xO are 46.5, 46.1, 50.6 and 48.9nm, respectively. FE-SEM analyses show that the structure of nanopowders changes from short stylolitic structure to long stylolitic structrue when Cr concentration x increases to 0.2. The absorption peaks of Cr-doped nanopowders are demonstrated by UV-Vis analysis, and E_g of ZnO are 3.17, 3.18, 3.19 and 3.23eV, respectively. Room temperature VSM reveals a weakly paramagnetism behavior of the as-prepared Zn_1-xCr_xO nanocrystalline.

A magnetic layered inorganic-inorganic composite involving manganese zinc ferrite (Mn_0.8Zn_0.2Fe₂O₄) and Mg-Al layered double hydroxides (MgAl-LDHs) was assembled by coprecipitation method. The products were characterized by TEM, FTIR, DTA, XRD and VSM. The results indicate that the composite has core-shell structure, the introduction of ferrite particles does not change the typical layered-structure of MgAl-LDHs phase. MgAl-LDHs has infinitely small magnetic shielding effect on ferrite particles, the saturation magnetization values of the composite increase linearly with the ferrite content, however, is the MgAl-LDHs content increasing, the ceorcivity values of the composite decrease first, then increase subsequently, but these changes are small on the whole. In addition, the LDHs layer also has infinitely small effect on the thermomagnetic effect of ferrite particles. It is obvious that the ferrite content in the composite plays a decisive role on magnetic properties and thermomagnetic effect.

Using RF magnetron sputtering method, La_0.75Na_0.25MnO₃ film with thickness of 120nm was epitaxially grown on (100) LaAlO₃ single-crystal substrate. The thin film was characterized by X-ray diffraction, Superconducting quantum interference device and DC four probed method. The results indicate that the thin film shows a well epitaxial direction of (100) and the Curie temperature is 270K. Near the Curie temperature, the magnetic property shows a transition from ferromagnetic to paramagnetic character. La_0.75Na_0.25MnO₃ thin film exhibits a characteristic spin glass state, which is due to strain effect. The thin film exhibits a quite distinctive magnetoresistance effect which is 40.3％ near the Curie temperature when the magnetic field is 1T. Transport properties indicate that the resistivity satisfies the formula of ρ=ρ₀+ρ₁T²+ρ₂T⁵ from 80K to 210K which is due to electron-electron scattering, the resistivity satisfies phase separate percolation model from 220K to TMI, the resistivity satisfies polarons model when the temperature is above TMI which is due to the existence of the small polarons nearest hopping.

Ba_0.6Sr_0.4TiO₃ (BST40) thick film with thickness of 33μm was prepared by electrophoretic deposition method on Pt/Ti/SiO₂/Si substrate using the BST40 nano powders as precursor. A high pressure treatment process was introduced in order to increase the density and decrease the sintering temperature of the film. The composition and surface morphology of the BST40 thick film were characterized. The ε-V curve of the BST40 thick film was measured. The leakage current density was tested and hysteresis loops of the thick film were measured at different temperatures. The results show that a dense and no crack surface are formed after sintering at 950℃. A tunability of 59.2％ is calculated according to the ε-V curve. The leakage current is less than 100μA/cm ² when the applied voltage shifts from --25V to 25V. The remnant polarization is 1.06μC/cm² at the temperature of 0℃ and the frequency of 1kHz.

Using Ca(NO₃)₂·4H₂O, Mg(NO₃)₂·6H₂O and Si(OC₂H ₅)₄ as precursors, (Ca_0.7Mg_0.3)SiO₃ powders were prepared by sol-gel method. The crystalline phase, microstructure, sintering characteristic and microwave dielectric properties of (Ca_0.7 Mg_0.3)SiO₃ powders calcined at different temperatures were studied. The results show that the powders calcined at 800℃ are almost amorphous and a large amount of crystalline phases are occurred when the calcination temperature increases to 900℃. The dielectric ceramics made from amorphous powders or fine powders (calcined at 900℃) can’t achieve compact structure, and the sintering characteristic and microwave dielectric properties can be enhanced by increasing the size of grains. Using (Ca_0.7 Mg_{0. 3})SiO₃ powders with grain sizes of 50--100nm and 90--300nm as raw materials, the ceramics sintered at 1320℃ possess good microwave dielectric properties: ε=6.62, Q× f=36962GHz, τ_f=-48.32×10^-6℃^-1 and ε=6.71, Q× f=41842GHz, τ_f=-49.63×10^-6℃^-1, respectively.

(1-x)CaTiO_3-x(Li_1/2Sm_1/2)TiO₃ microwave dielectric ceramics were prepared by solid sate reaction technique. The crystal structure, sintering properties and microwave dielectric properties of the ceramics were investigated. The results show that a single orthorhombic perovskite structure forms in the x range from 0.1 to 0.9; the best sintering temperatures of (1-x)CaTiO_3-x(Li_1/2Sm_1/2)TiO₃ are 1250℃ and 1300℃ in the x range from 0.1 to 0.5 and 0.6 to 0.9, respectively; the dielectric constant εr, the product of quality factor and resonance frequency (Qf ) value and the temperature coefficient of resonant frequency τf decrease with the increasing of x. The Ca_0.3(Li_1/2Sm_1/2)_0.7TiO₃ ceramic sintered at 1300℃ for 5h exhibits excellent microwave dielectric properties: ε_r=116.5, Qf=3254GHz, τ_f=42.43×10^-6/℃.

Pt/SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂/p-Si heterostructures were fabricated by sol-gel method. The effects of annealing temperature on microstructure, crystal growth behavior, leakage current density, and C-V characteristics of Pt/SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂/p-Si heterostructure were investigated. The SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂ multilayer thin films annealed at low temperature are polycrystalline, and grow in the preferred c-axis orientation with the increase of annealing temperature. The C-V curves of Pt/SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂/p-Si heterostructure annealed at various temperatures all show a clockwise ferroelectric hysteresis loop. The widths of C-V hysteresis loops of Pt/SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂/p-Si heterostructure increase with the increase of annealing temperature and reach a maximum of 0.78V when the heterostructure is annealed at 700℃. The leakage current density of Pt/SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂/p-Si heterostructure decrease slowly with the increase of annealing temperature from 550℃ to 650℃. However, when the annealing temperature is above 650℃, the leakage current density of Pt/SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂/p-Si heterostructure increase evidently. The lowest leakage current density is 2.54×10^-7A/cm² when Pt/SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂/p-Si heterostructure is annealed at 650℃.

Porous Si₃N₄ ceramics were prepared by in situ reaction-bonding technology, using Si₃N₄ and Al₂O₃ as starting materials. The effects of sintering temperature and holding time on their porosities, flexural strength, and dielectric properties were studied. The strength and dielectric constants of samples are improved with increasing of sintering temperature and holding time; but the result is reverse in the condition of sintering temperature >1350℃ and holding time >4h. The phase analyses results indicate that the porous Si₃N₄ ceramics are mainly composed of α-Si₃N₄, oxidated SiO₂ (cristobalite) and Al₂O₃. Porous Si₃N₄ ceramics with porosities from 25.34% to 43.92% and flexural strength from 42.54 to 127.85MPa are obtained. Their dielectric constants are in the range from 3.3 to 4.6 and dielectric loss is about 0.005.

Co-filled skutterudites Ca_mSm_nFe_xCo_4-xSb ₁₂ were prepared by melting method and spark plasma sintering (SPS) technique, and the effects of filling amount and fraction of Ca and Sm on the thermoelectric properties of these compounds were investigated. For p-type Ca_mSm_nFe_xCo_4-xSb ₁₂ , with the Ca and Sm co-filling amount increasing, the Seebeck coefficient increases, but the electrical conductivity and the thermal conductivity decrease. When the Ca and Sm co-filling amount is fixed, the electrical conductivity of skutterudites increases with increasing Ca filling fraction, the thermal conductivity decreases and the Seebeck coefficient increases with the increase of Sm filling fraction. At 775K, the highest figure of merit value of 0.85 is obtained for Ca_0.15Sm_0.24Fe_1.51Co_2.48Sb₁₂.

Nanocomposite structure is one of the promising directions towards advanced bulk thermoelectric materials. An n-type CoSb₃ nanocomposite consisting nano- and micro-sized grains was prepared by in~situ solvothermal synthesis and hot pressing. Using CoCl₂ and SbCl₃ as precursors, NaBH₄ as reductant, and ethanol as solvent, the start materials together with micro-grained n-type CoSb₃ powders prepared by melting/annealing method were put into an autoclave and reacted at 250℃ for 72h. The bulk nanocomposite was prepared by hot pressing the as-synthesized products. The introduction of nanocomposite structure can reduce the thermal conductivity efficiently by interface scattering and increase the Seebeck coefficient by quantum confinement due to the nanoscale constituents, thereby improve the thermoelectric performance. It is shown that the composite has a doped semicondoctor behavior with good electrical properties. The phonon scattering is efficiently enhanced by the composite micro-/nano-structure, which reduces the thermal conductivity to 2.0-2.3W·m^-1·K^-1 in the nanocomposite. The highest dimensionless figure of merit obtained in the present work reaches 0.5 at 600K.

Composite perovskite oxides La_1-xSr_xCo_1-yFe_yO_3-δ (LSCF) is an optional cathode material for the intermediate temperature solid oxide fuel cells. La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ powders were synthesized by a citrate method. The effects of the precursor solution pH value and the calcining temperature on the phase structure of the LSCF powders were investigated by Xray diffraction. Besides, the impacts of the precursor solution pH value and sintering temperature on the morphology and impedance characteristics of the LSCF sintered bodies were studied by SEM, AC impedance analysis, respectively. The alternatecurrent impedances of the LSCF sintered bodies were analysized based on the Voigttype equivalent circuit model.
The results show that the LSCF sintered body has the lowest impedance in the condition that the precursor solution pH is 4, the calcination temperature is 900℃, and the sintering temperature is 1400℃ for 2h, respectively.

A novel C/SiC/Si-Mo-Cr multilayer oxidation protective coating for carbon/carbon composites was prepared by pack cementation and slurry method. The microstructures of the as-prepared multilayer coating were characterized by XRD and SEM analyses. The effects of the coating processing and thermal shock on the mechanical properties of carbon/carbon composites were investigated by three point bending tests. The results show that the asobtained multiphase coating is dense, and the flexural strength of carbon/carbon composites after coating increases and the fracture behavior changes from the pseudoplastic fracture to brittle fracture mode. After enduring the thermal cycling between 1500℃ and room temperature for 20 cycles, the flexural strength of the coated specimens decreases accordingly, and the plastic increases.

Tension-tension fatigue experiments were conducted at room temperature and in water vapor containing environment at 1300℃, using a stress ratio of 0.1 at sinusoidal frequency of 3Hz. The results show that the fatigue limit (based on 10⁵ cycles) in the above two environments are 244.8MPa and 90.8MPa, respectively. Oxidation is the dominant damage mechanism. Based on the microstructure observation of the fracture surfaces, it is concluded that in water-vapor containing environment at 1300℃, sufficiently high stress remarkably weakens the sealing effect of SiO₂, which enables the oxidizing species to diffuse through the coating cracks caused by the applied stress. The higher the applied stress, the higher the gaseous diffusivity, the shorter the composite fatigue life.

ZrB₂-SiC and C_sf/ZrB₂-SiC, two kinds of ultra-high temperature ceramic composites were fabricated by hot-pressing. The ablation behavior of them was studied by oxyacetylene torch test at a heat flux of 4186.8kW/m2 for 180s. For ZrB2-SiC, the surface temperature increases to 2406℃ during torch test and the average mass loss is -0.14%, linear ablation rate is
-1×10^-3mm/s. For C_sf/ZrB₂-SiC, the maximum surface temperature is 1883℃, and the average mass loss is -0.19%, linear ablation rate is -4×10^-4mm/s. From the surface and cross section analysis it is found that loosen ZrO₂ oxidation layer, SiC rich layer and unaltered layer form from outer layer to inner layer in ablated ZrB₂-SiC microstructure, where SiC rich layer has oxidation resistance. For C_sf/ZrB₂-SiC, ZrO₂-SiO₂ oxidation layer, SiC depletion layer and unaltered layer distribute from outer layer to inner layer, where the SiO₂ filled ZrO₂ oxidation layer formed in the surface can prevent
oxygen effectively.

Silica sols and silica membranes modified by methyltriethoxysilane(MTES) were prepared by acid catalysed co-hydrolysis and condensation reaction of tetraethylorthosilicate(TEOS) and MTES. The influences of hydrophobic group content on the stability of the silica sols and the surface wettability and vapour stability of the silica membranes were investigated. The results show that the stability of silica sols decreases with MTES/TEOS molar ratio increasing. As MTES/TEOS molar ratio increasing, the surface free energy and surface wettability of the silica membranes decrease greatly. It is mainly because the polar force in surface tension decreases which results from the increase of CH₃ nonpolar group on the surface of silica particles shown from FTIR analysis. When the silica membranes age in moist condition, the changes of contact angles and water shoulcl be decrease with MTES/TEOS molar ratio increasing. For hydrophobic silica membranes, MTES/TEOS molar ratio should be controlled between 0.8 and 1.0. AFM image shows that the silica membrane on the ceramic support is continuous and the surface is relatively even and smooth.

CaBi₄Ti₄O₁₅ coatings were fabricated on Al₂O₃ substrates with a simple spin coating method. These coatings were annealed at different temperatures and then kept in air at 120℃ for several days. The microstructures of CaBi₄Ti₄O₁₅ coatings were
studied by using SEM. CaBi₄Ti₄O₁₅ coatings display distinct wettability from superhydrophobicity to hydrophilicity, the
corresponding surface contact angles change from 152.5° to 43.6°. The SEM observation indicates the size change of crystal grains and cavities of rough surfaces is the main reason why the wettability of CaBi₄Ti₄O₁₅ coatings changes from superhydrophobicity to hydrophilicity, and the intrinsically hydrophilic material performs non-wetting due to rough hierarchical structure with nano-particles.

CsI(Tl) films were prepared by thermal evaporation and annealed at various temperatures. Structure and scintillation properties of the films were examined using X-ray diffraction, scanning electron microscope, X-ray fluorescence spectrometry, positron annihilation lifetime spectroscope and scintillation pulse height spectrometry. Results show that the CsI films are in micro-columnar structure with a preferential (200) orientation. When the sample is annealed at 150℃, Tl⁺ ions diffuse to the sample surface. Consequently, the amount and size of the vacancy type of defects increase. However, the light yield increases a little after annealed. The samples annealed at 250℃ have a good crystalline state and scintillation properties. As the annealing temperature increases to 400℃, the light output of the samples decreases seriously due to the dramatic change of their microstructure and the decrease of Ti⁺.

ZnO thin film was prepared on the 6H-SiC single crystal substrate by pulsed laser deposition (PLD) method. X-ray diffraction(XRD), reflection high energy electron diffraction(RHEED) and Phi scan of grazing incidence X-ray diffraction with synchrotron radiation (SRGID) were employed to investigate the structure properties of ZnO thin film. The results show that single crystal ZnO thin film is prepared on 6H-SiC single crystal substrate. The results of SRGID with different grazing incidence angles indicate that the crystal relaxation along the c-axis in ZnO thin film is not uniform. The crystal parameters of a-axis are 0.3264, 0.3272 and 0.3223nm respectively, which correspond to the detected
depth of the interface layers, the middle section and the surface layers of the ZnO film. The calculated results show that the Poisson ratio of ZnO thin film is 0.504 and the lattice mismatch of a-axis between the ZnO thin film and 6H-SiC substrate is 5.84%.

Influence of modulating ratio on friction and wear behavior of TiN/Ti multilayer coatings was studied. Filtered cathode vacuum arc(FCVA) deposition method was applied in preparation of TiN/Ti multilayer coatings with different modulating ratios. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used in the film structure observation and individual layer analysis. Furthermore, nanohardness and elastic module were tested by nano-indenter and the friction and wear experiment was carried out on SRV tester. The experimental results show clear laminate structures in TiN/Ti multilayer coatings and good bonding between film and substrate. Nanohardness and the wear behavior are influenced remarkably by modulating ratio. Influence of modulating ratio on friction of multilayer coatings is relatively weak. Finally, the relationship between the ratio of hardness and elastic module (H/E) and the wear behavior of TiN/Ti multilayer coatings is discussed.

Porous silicon nitride ceramics with a biomorphic microstructure were manufactured by
carbothermal reduction and nitridation of Y2O3/SiO2/charcoal composites in high concentration nitrogen atmospheres(0.6MPa) at 1600℃. These
composites were prepared from pine-derived charcoal impregnated with yttrium-incorporated silica mixed sol by vacuum/pressure infiltration
process. The influences of sintering temperature, reaction time, additive and sintering atmosphere on microstructure and phase composition were studied by XRD, SEM. The formation mechanism of Si3N4 was analyzed. XRD analysis shows that mainly \β-Si3N4 and minor glass component of
Y8Si4N4O{14 are detected. SEM observation reveals that the resulting porous Si3N4 retains the microcellular morphology of original pinewood tissue, and the remarkable rod-like \β-Si3N4 grains grow from the internal walls of macroscopic pores. The sintering process of porous \β-Si3N4 consists of three stages, namely, formation of α-Si3N4, transformation of α-\β and grain growth, respectively. Nitridation is based on gas-solid and gas-gas reaction among SiO(g), N2(g), C(s) or CO(g) for the samples treated at 1450℃. Porous ceramics with elongated fibrous \β-Si3N4 grain is developed by solution-reprecipitation mechanism at 1600℃.

Damp-proof and enhanced coating was fabricated on the porous Si₃N₄ substrate by sol-gel method, with CaO-SiO ₂-B₂O₃ as adhesive and sintering aids. The phase structure of the coating was characterized by X-ray diffraction (XRD). The morphology of the coating was characterized by scanning electron microscope (SEM). The density, water absorption and porosity of the porous Si₃N₄ were tested by Archimedes method. The bending strength of the coating was measured with SANS materials testing machine. The dielectric constant and dielectric loss were measured with the LCR tester model YY2813B. The results show that the water absorption of the porous Si₃N₄ is decreased by 90.99% to 96.97%, the bending strength of the porous Si₃N₄ is increased by 9% to 22%, the density, dielectric constant and dielectric loss of the porous Si₃N₄ are influenced little by sealing process.

Modification of SiC coating was carried out with B and BC_x prepared by chemical vapor deposition(CVD), SiC/B/SiC and SiC/BC _x/SiC multi-layer self-healing coatings were prepared on a two-dimensional C/SiC composite. The surface and cross section morphologies of the multi-layer coatings were analyzed by SEM. Oxidation were carried out in static air at 700℃. The results show that the B₂O₃ glass produced by oxidation of B or BC_x can seal the cracks existed in the coating well, the kinetics of oxidation is controlled by
diffusion of oxygen through the micro-cracks and B₂O₃ glass layer; SiC/BC _x/SiC-C/SiC composites have lower weight loss during the oxidation
and higher strength retention after oxidized for 10h.

To prevent carbon/carbon composites from oxidation, a MoSi₂-Mo₅Si₃/SiC multi-coating was prepared by the
chemical vapor reaction (CVR) technique and slurry method. The formation mechanism and structure of the multi-coating were studied by using XRD, SEM and EDS analysis, and then the anti-oxidation property of the multi-coating was investigated. The results show that the thickness of obtained coating is about 400μm, and the main phase are composed of β-SiC, MoSi₂ and Mo₅Si₃. After oxidation in air at 1350℃ for 10h, the weight loss of the multi-coating is only 1.21%, which is obviously lower than that of single-layer SiC coating. The phases of MoSi₂ and Mo₅Si₃ formed in the MoSi₂-Mo₅Si₃/SiC multi-coating fill the cracks and holes in the monolayer SiC coating, which can improve the anti-oxidation ability of the multi-coating. So the multi-coating made by the complex technology possesses more compact structure and better anti-oxidation property.

Various Plasma Electrolytic Oxidation (PEO) ceramic coatings were prepared on LY12 aluminum alloy by adjusting the concentration of sodium silicate solution. Optical microscope (OM), XRD and EIS were used to study their morphology, composition and anti corrosion behavior in NaCl solution. Increasing concentration of sodium silicate leads to the increase of the total coating thickness while too high and too low concentration lead to the decrease of inner dense layer. The main composition of PEO coatings prepared in 20, 40 and above 60g/L concentration solution are correspondingly alumina, alumina with mullite, and amorphous phase. The
corrosion resistance is determined by the inner dense layer. Increasing the thickness of inner dense layer can improve the anti-corrosion performance. PEO coating’s corrosion resistance in acidic, alkaline and neutral NaCl solution is proved and the corrosion mechanism involved is also discussed.

In order to investigate the thermal stability of the tetrahedral amorphous carbon(ta-C) films fabricated by filtered cathodic arc deposition technique, ta-C films were annealed in ambient air for 3h. The annealing temperature was 200℃, 400℃ and
500℃, respectively. XPS and Raman spectroscope were employed to characterize the changes of the microstructure of the films. The results show that the XPS C1s peaks and the Raman peaks of the samples annealed at 400℃ or below change little. When the annealing temperature
is 500℃, the shape of the XPS C1_s peak doesn’t change too; the Raman I_D/I_G increases, the G-peak position doesn’t change and
the shape of Raman peak becomes more symmetry. This reveals that the sizes of the graphite clusters in the films increase and no obvious graphitization occurs during annealing process. All these indicate that the ta-C film fabricated by filtered cathodic vacuum arc technique has excellent thermal stability due to its hydrogen free and dense structure. Besides, parts of the films along the edge of the samples is evaporated by oxidation when the annealing temperature is up to 500℃.

Using exfoliatable graphite, Fe(NO₃)₃, Co(NO₃)₂ and citric acid as raw materials, magnetic exfoliated graphite (MEG) was prepared by citrate sol-gel process. The microcosmic performance and magnetic property of MEG were characterized by SEM, EDS, XRD and hysteresis loop. In addition, the effects of raw material ratio, pH value of exfoliatable graphite and expanded time on magnetic property and adsorption oil capacity of MEG were studied. Based on the factors of magnetic intensive, adsorption oil capacity and costs of preparation and so on, the optimum preparation conditions of MEG are found as follows, the ratio of exfoliatable graphite to ferrite is 2:1, the pH value of exfoliatable graphite is 5 and the expanded time is 120s at 900℃. The experimental results show that ferrite can be effectively deposited which is homogeneous distribution on/between exfoliatable graphite in the optimum preparation condition, and the prepared MEG has high magnetic intensive and adsorption oil capacity. The saturation magnetization and adsorption oil capacity of
MEG are 17.95A·m²·kg^-1 and 32.6g·g^-1, respectively.

The carbon electrode materials for electrochemical capacitors were prepared from petroleum coke precursor carbonized at different temperatures followed by KOH activation. The precursors and activated products were characterized by XRD, TEM and N₂ adsorption techniques. The capacitive behavior of activated petroleum coke was also examined. Results show that crystallite structure and pore structure of activated petroleum cokes can be controlled by adjusting the precarbonization temperature, and so non-crystalline high surface area activated carbons and crystalline low surface area novel activated carbons which consist of large amount of graphite-like crystallite are obtained. The energy storage for the low surface area activated carbon depends on the intercalation of electrolyte ions into graphite-like crystallite layers during the charge process. The surface specific capacitance of the low surface area activated carbon is over ten times of that for high surface activated carbon, and the low surface area activated carbon has a higher volumetric specific capacitance.

Catalyst particles coated uniformly on cordierite surface through dipping-method in nickel nitrate solution, were used to synthesize carbon nanotubes via methane diffusion flame method. Well-graphitized carbon nanotubes were synthesized with outer diameters of 30--50nm and length of tens of micron meter. The results show that diameters of carbon nanotubes are not affected by the size of particles on substrate surface, which increase with the concentration of dipping solution. When catalyst particles become denser with dipping time extending, the density of carbon nanotubes increases obviously with bound morphology. The catalytic mechanism is discussed in detail to propose the growth of carbon nanotubes and suggests the possible changes of particles during this process.

High-density SiC ceramics doped with 2wt% Al₂O₃ additives were fabricated by ultra-high
pressure and high temperature technique (4.5GPa,1250℃,20min). The structures, grain size, lattice parameters, chemical component, morphology and mechanical property of the sintered SiC ceramics were characterized by X-ray diffraction
(XRD), X-ray photoelectron energy spectroscope (XPS), scanning electron microscope (SEM), energy dispersive X-ray
spectroscope (EDX) and nano impress indenter. The results show that nano-SiC ceramic is fully densified by ultra-high
pressure technique at relative low temperature (1250±50℃). No phase transfer or holes is found in the sintered nano-SiC
ceramic. The hardness and elastic modulus of the sintered SiC ceramic with grain size of 22nm and lattice parameters of 0.4355nm are 33.7GPa and 407GPa, respectively.

Based on the basic principle of carbothermal reduction reactions in the ZrO₂-B₂O₃-C system, ultra-fine ZrB₂-ZrC composite powders were synthesized by sol-gel method using zirconium oxychloride, boric acid and phenolic resin as sources of zirconia, boron oxide and carbon, respectively. Thermodynamic change process, phase compositions, crystallite size and morphology of the synthesized powders were characterized by thermogravimetry-differential thermal analysis, X-ray diffraction and scanning electron microscope. The results show that ZrB₂ and ZrC phases form at 1300℃. The carbothermal reduction reactions are completely finished when calcined at 1500℃ for 1h. The average crystallite size and specific surface area are about 200nm and 87m²/g, respectively. The agglomeration phenomenon is improved by adding 1.0wt% polyethylene glycol.

Silicon nitride ceramics was prepared by super-high pressure using the γ-Si₃N₄ powders synthesized by the shock-wave technique as raw materials and with Y₂O₃-Al₂O₃-La₂O₃ mixtures as additives at 5.7GPa from 1370K to 1670K. The stability, relative density, mechanical properties and microstructure of the compacts synthesized at different temperatures were investigated. The results show that γ-Si₃N₄ is completely transformed to β-Si₃N₄ at temperature from 1420K to 1670K,
and partly transformed to β-Si₃N₄ at 1370K. Micro-analysis indicates that the typical microstructure of sintered Si₃N₄ is mainly composed of β-Si₃N₄ rod crystals with disordered orientation and uniform microstructures. The relative density
and Vickers hardness in the as-sintered (5.7GPa, 1370K) samples are 98.83% and 21.09GPa, respectively.

Eu³⁺-doped Lu₂O₃ phosphor nanopowders were synthesized by co-precipitation process with NH₃·H₂O, NH₄HCO₃ and the mixed solution of NH₃·H₂O and NH₄HCO₃ as the precipitants, respectively. Effects of precipitants on microstructures and properties of obtained Lu₂O₃ phosphor were investigated on study of decomposition behavior of precipitate precursor by means of DTA-TG-MS and FTIR spectra. The morphologies and particle size distributions of obtained Lu₂O₃ phosphors were characterized. It is found that powders from the mixed precipitant method exhibits best microstructural morphology with weak agglomeration state and particle size distribution. After being calcined at 1000℃ for 2h, the average crystalline size of Lu₂O₃ reaches 35nm with medium particle size (D₅₀) of 0.48μm.

The Ce ³⁺ ions and B₂O₃ component were introduced into the Er³⁺-doped Bi₂O₃-GeO₂-Ga₂O₃-Na₂O glasses, respectively. And the suppression of excited state absorption of Er³⁺ :⁴I_11/2level was investigated under the excitation of 975nm LD. With the introduction of Ce³⁺ ion or B₂O₃ component, the energy transfer between Er³⁺ :⁴I_11/2 and Ce³⁺:²F_5/2 levels or the multi-phonon relaxation rate of Er³⁺:⁴I_11/2→⁴I_13/2 increase, respectively, and the excited state absorption is suppressed efficiently owing to the evident decrease of ⁴I_11/2 level fluorescence lifetime. Meanwhile, the results
show that the total quantum efficiency of Er³⁺:⁴I_13/2→⁴I_15/2 is enhanced in the case of Ce³⁺ ion doping, and the fluorescence intensity of 1.55μm radiative transition is improved accordingly while its effective spectral width is almost
unchanged. In the case of B₂O₃ component introduction, although the 1.55μm fluorescence intensity is somewhat weakened, its effective spectral width is further broadened and the peak wavelength of gain cross-section shifts to longer wavelength region.

When an external magnetic field was applied on the suspension composed of ferromagnetic Ni and nonmagnetic ZrO₂ particles, the viscosity of the suspension increased drastically. The relation of viscosity and inner structure of suspension was investigated by using magnetic coils, rotational viscometer and optical microscope. The results show that the viscosity increases with the magnetic field strength and Ni content increasing because of the formation of chain-like clusters in the suspension. As the magnetic field increases, Ni clusters become larger, which hinders the free move of particles, so the viscosity increases. Similarly, Ni clusters in the suspension increase with Ni content increasing, and hence the viscosity increases.

The Al₂O₃-based seals were prepared by tape casting process using Al₂O₃ and Al fine powders as primary starting materials. The materials’ hermetic properties were tested in simulative environment of the sealing of planar ITSOFC, and the materials after hermetic property test were characterized by X-ray diffraction and scanning electron microscope. The results show the flexible Al₂O₃-based seals are successfully prepared by appropriate tape casting process. The Al₂O₃-based seals have favorable sealing characteristics even though the compressive stresses are quite low. The leak paths are reduced and the tortuosity of leak paths are aggrandized when Al fine powders are added into Al₂O₃-based seals, which enhance the materials’ hermetic property and mid-term stabilities. It is feasible that Al₂O₃-based seals with 10wt%--20wt% Al fine powders prepared by tape casting are used as sealing materials for the planar ITSOFCs.

Pd-Fe/C catalysts were prepared by the impregnation-reduction method. The ratios of Pd to Fe were 1:1, 2:1, 1:2, respectively. The catalysts were characterized by transmission electron microscope (TEM) and powder X-ray diffraction (XRD). The results indicate that the catalyst particles are homogeneously distributed in the carrier. The average particle sizes are less than 5nm. The influence of adding Fe on Pd/C catalyst crystal structure was also studied. Finally, the activation of Pd-Fe/C catalysts with different Pd/C ratios to the electrocatalytic oxidation of formic acid was investigated. The results show that the catalytic performances of Pd/C catalyst are improved by adding suitable Fe; the catalytic performance of the Pd-Fe/C catalysts reaches the best when the atom ration of Pd:Fe equal to 1:1.

The preparation technics of periodically poled LiNbO₃ crystal (PPLN) was studied and the effects of external field characteristics including magnitude, duration of voltage pulse on periodic poling process were investigated. Improving magnitude of pulse could accelerate the poling process. After a detailed study of all technological steps, a resolution to overvcoming fringe breakdown is proposed, i.e. appropriate electrode figure and optimum waveform must be selected. By using the technics proposed, ratio of finished product reaches 90%. To eliminate the negative effects of reverse domain side expansion, a thin insulator layer is coated on the samples and the electrode width is optimized. By this method, high-quality periodically poled LiNbO₃, which meets the expected occupation ratio perfectly, is prepared successfully.

The thermodynamic properties of transporting reactions in ZnSe-I₂, -H₂, -HCl and -NH₄Cl chemical vapor transport systems were analyzed by solving sets of equations with numerical methods. The results show that ZnSe-NH₄Cl system has the properties of high total pressure and moderate reaction enthalpy change. The hydrogen (H₂) produced through decomposition of NH₃ is capable to adjust the transporting component partial pressure of H₂Se. Referring to the component partial pressure in ZnSe-I₂ system, the process parameters in ZnSe-NH₄Cl system are primarily selected for ZnSe single crystal growth. The concentration of NH₄Cl ranges from 0.5 to 1.0mg/mL at the growth temperature of about 1000℃. An as-grown ZnSe single crystal is obtained
with dimension of 8mm×6mm×4mm. The full width at half maximum of X-ray double crystals rocking curve on (111) as-grown surface is 60.48’’ and the etching pits density (EPD) is about (4.5--5.0)×10⁴/cm².

A new method of protein adsorption was investigated for the preparation of nanosized flake Na_xCo₂O₄ compounds. The effects of BSA on the formation of the Na_xCo₂O₄ compounds were investigated. The results show that the average particle size of colloidal precursor can be clearly decreased with the increasing of BSA concentration to 1.5--2.5mg/mL. The formation of γ-Na_0.71Co_0.96O₂ crystalline phase is inhibited with the increasing of BSA concentration. The crystalline phase composition and morphology of calcined precursor are influenced by BSA obviously. After calcined at 800℃, ultra-thin flake γ-Na_0.71Co_0.96O₂ crystals are obtained with about 200 nm in thickness and about 1--5μm in width along the plane direction. Compared with solid state reaction, the thickness of flake Na_xCo₂O₄ crystals obtained by this new method is dramatically decreased.