The mechanism of preferential orientation and surfacereconstruction of CIS thin films was systematically investigated. Epitaxial CISthin films with orientations of (220/204), (001) and (112) were deposited onGaAs(110), (001), (111)A and (111)B substrates, respectively, by using ametal-sputtering and Se-evaporation hybrid technique. The main epitaxialrelationship was found to be GaAs(110) // CIS(220), GaAs(001) // CIS(001), and GaAs(111) // CIS(112), respectively. The morphological and structuralproperties of CIS thin films were determined by scanning electron microscope,atomic force microscope and X-ray diffraction. The (220/204) and (001) surfacesof CIS thin films were found to be unstable under the growth conditions. The depositedsurfaces were mainly covered by the lowest specific surface-energy (112) facetregardless of its orientation. Sequence of the specific surface-energy for CISfacets was deduced, based on the geometrical analysis of the defects. Solarcells with preferential oriented CIS thin films as absorber layers werefabricated. The (220/204)-oriented film is characterized to have the best photovoltaicperformance, which is consistent with the charge transportation and separationpreferring along [220] direction. It indicates that higher efficiency of CIS thinfilm solar cells can be expected by enhancing (220/204) orientation through processoptimization.

The sodiumdodecyl benzene sulfate (DBS) surfactant was used in the hydrothermal synthesisof TiO₂ nanomaterials. Without the addition of DBS in the TiO₂ Sol,theobtained sample is 10~20nm anatase TiO₂ nanoparticle. While with the additionof DBS, the obtained sample turns to rutile TiO₂ nanorod. Althoughthe dye adsorption ability and the photovoltaic performance of thephotoelectrode with rutile TiO₂ nanorod is poorer than that of thephotoelectrode with anatase TiO₂ nanoparticle, the rutile TiO₂nanorod has higher light scattering ability. When using the rutile TiO₂nanorod in the fabrication of the reflecting layer in the photoelectrode, thelayer can reflect light and convert energy. This new kind of reflecting layerin the photoelectrode shows higher efficiency in enhancing the energy conversionefficiency of dye-sensitized solar cell (with 26.14% enhancement) than that oftraditional Ti-nanoxide 300 reflecting layer (with 11.04% enhancement). Thereason is that the double functions of rutile TiO₂ nanorod reflectinglayer are superior than that of traditional Ti-nanoxide 300 reflecting layer inenhancing the short-circuit current density of dye-sensitized solar cell.

Li₄Ti₅O₁₂nanorods were prepared by hydrothermal ion exchange method. The weight lossprocess of Li₄Ti₅O₁₂ during the heat treatmentwas studied by thermogravimetric method (TG). The structure and composition ofthe samples obtained at different hydrothermal temperatures (150℃ and180℃) and different heat-treatment temperatures (600℃, 750℃ and900℃) were characterized by X-ray diffraction (XRD) andtransmission electron microscope (TEM). The electrochemical performances wereevaluated by means of various techniques including galvanostaticcharge/discharge tests and cycle voltammetry (CV) in terms of cyclingperformance and rate capability. The results indicate that Li₄Ti₅O₁₂nanorods can be synthesized after hydrothermal reaction at 180℃ by theway of ion exchanges. The first specific discharge capacity of the samples heat-treatedat 750℃ is 164 mAh/g with retention ratio of 98.33% after 50charge-discharge cycling, and the voltage plateau at 1.5V could be seen in thedischarge curves distinctively.

Mesoporousmagnesium manganese silicate as a cathode material for rechargeable magnesiumbatteries was prepared using mesoporous silica MCM-41 as both template and siliconsource. X-ray diffraction (XRD), scanning electron microscope (SEM),transmissionelectron microscope (TEM) and N₂ adsorption-desorption measurementswere performed to characterize the mesoporous structure of the as-preparedmaterial. Furthermore, the electrochemical performance of mesoporous and bulkmaterials were compared by cyclic voltammetry and direct currentcharge-discharge measurements. The larger surface area of the mesoporous material favors the efficientcontact between active material and electrolyte, providing more active sitesfor the electrochemical reaction. As a result, the mesoporous material exhibitsbetter electrochemical performance with lower polarization for magnesium de-intercalationand intercalation, larger discharge capacity and higher discharge flat plateaucompared with corresponding bulk material. In 0.25 mol/L Mg(AlCl₂EtBu)₂/THFelectrolyte, the initialdischarge capacity and discharge voltage plateau of the mesoporous material canreach 241.8 mAh/g and 1.65V, respectively. The mesoporous structure may providea new approach to improve the reaction activity of the cathode materials for rechargeablemagnesium batteries.

Boehmite Sols were used as aluminum precursorsfor preparing mesoporous alumina with crystalline framework walls in thepresence of 1-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM][BF₄]). T hestructureof theγ-Al₂O₃ wasexamined by N₂ physicaladsorption, X-ray powder diffraction (XRD), transmission electron microscope (TEM), and solidstate ²⁷Al MAS NMR spectra. The results show that aluminawith the three-dimensional interconnected scaffold-like channels displays very richporosities with large mesopores, and the addition of [BMIM][BF₄]could improve the pore properties of alumina significantly.

Usingreduced iron powder and activated carbon as starting materials, micron-levelhollow carbon rosary structures were synthesized by thermal CVD method. Their morphology,composition and specific surface area and pore-size distribution of the productwere characterized by TEM, HRTEM, EDS and N₂ adsorption apparatus.With dozens microns in length and 1-2 μm in diameter, the rosarystructures were formed by hollow carbons. The hollow carbon actually wasgraphite shells with 3-5 nm in thickness. Thespecific surface area S_BETof the product was up to 306.523 m²/g, and the pore-size was mainlydistributed in the mesoporous range, whose peak mark at 3.761 nm. The mechanismof the product can be described as follows, carbon was precipitated in the formof graphene pieces at lower temperature by iron/C droplet, which epitaxiallygrew on iron/C droplet and formed graphite shells. The graphite shells andiron/C droplet constituted shell/core structures. The contraction trend ofgraphite shells squeezed the iron/C droplet along the axial direction. Theprocesses above repeated and the carbon rosary structures formed. The product may have potential applications in the energy-savingmaterials, supporter materials for drugs/dyes/catalysts, hydrogen/energystorage materials.

Hierarchical macro-mesoporous carbon material (HMMC)was synthesized successfully <>via a facile dual-templating method usingresols as carbon source, in which polystyrene (PS) colloid was selected as macroporoustemplate and Pluronic F127 as mesoporous template. After thermosettingtreatment and carbonization step, HMMC can be obtained. The product was characterizedby XRD, SEM, TEM and N₂ adsorption techniques. The electrochemical performanceof HMMC was evaluated by cyclic voltammetry and galvanostatic charge/dischargemethods using an electrochemical workstation and a battery testing system. Resultsshow that HMMC material has three-dimensional connected macroporous structurewith pore size of 1μm andordered mesoporous windows with average pore size of approximately 5nm. BET surface area of the product is 353.8 m²/gand pore volume is 0.36cm³/g. TheCV curves of HMMC are quasi-rectangular, the specific capacitance of product iscalculated to be about 40F/g at a constant current density of 50mA/g. It isanticipated that these novel materials synthesized by the simple methods havepotential applications in electrode materials.

Therelationship between the pore structure parameter of pitch-based sphericalactivated carbons (PSACs) and adsorption capacity ofCO₂ was investigated as well as the desorption performance. The pore structure characteristics of PSACs were analyzed by nitrogenadsorption at 77K and the equilibrium adsorption amount of CO₂ wasdetermined through the breakthrough curve. The results indicated that there wasa linear relationship between the equilibrium adsorption amount of CO₂and the specific surface area of micropores with pore size smaller than 1 nm.When 5% melamine was coated on the surface of PSAC, the equilibrium adsorptionamount of CO₂ increased 26.3% from 0.91 mmol/g to 1.15 mmol/g. Thedesorption cycle efficiency of CO₂ is 74.6% with Vacuum SwingAdsorption (VSA), while it can reach 100% with combined Electric SwingAdsorption (ESA) and VSA.

Anatase-type titanium dioxide filmson the titanium sponge substrate with grain size of about 0.5 m m were prepared by onestep hydrothermal treatment using hydrogen peroxide as oxidant and potassiumhydroxide as mineralizer, and the photocatalytic property of the as-preparedfilms was determined by the degradation of the methylene blue under irradiationof UV light. The effects of the concentration of potassium hydroxide on the crystalphase, morphology and photocatalytic property of titanium dioxide films were alsostudied. The results showed that potassium hydroxide promoted the crystallizationof thetitaniumdioxide. And with a concentration of 0.12mol/L of potassium hydroxide solution,the film had the best photocatalytic property with a 95% degradation rate after45 min UV-irradiation. The as-prepared TiO₂ films could be easilyrecycled and the photocatalytic property of recycled films was not markedlydecreased.

CeO₂nanotubes were synthesized by hydrothermal method using PEO-PPO-PEO (P123) as surfactant.The effects of reaction time, reaction temperature and concentration ofsurfactant on the formation of CeO₂ nanotubes were investigated. Themicrostructures of the samples were characterized by transmission electron microscope,X-ray diffraction and N₂ adsorption-desorption methods. The catalyticproperties of CeO₂ samples on methylene blue were also examined. Theresults indicate that single crystal CeO₂ nanotubes are obtainedwhen reaction time is 72 h, reaction temperature is 160℃ and molar ratio of P123 to CeCl₃·7H₂O is 1:5. Theexternal diameter of CeO₂ nanotubes is 40-60 nm, theirinternal diameter is about 20 nm and their length is 500-1000 nm. Theformation mechanism of CeO₂ nanotubes is subjected to dissolution-recrystallization,anisotropic growth and self crimping of Ce(OH)₃ crystal seed.Compared with CeO₂ nanoparticles and nanorods, CeO₂nanotubes demonstrate better catalytic activity on methylene blue, which isattributed to the remarkable adsorption of pore, exposure of higher activesurface (110) and considerable defects on the surface of CeO₂nanotubes.

The carbon membranesderived from the PPESK precursor in CHCl₃solvent for gas separation wereprepared with freezing and refrigeration drying methods. The influences ofdrying methods on the structure and gas separation performance of PPESK carbonmembranes were investigated. FTIR, TG, XRD and gas permeation tests were used to characterize thechange of chemical and carbon structure and gas separation properties of carbonmembranes prepared with different drying methods. The result indicated that theeffects of drying methods on the structure and performance of PPESK carbonmembranes are to promote the precursor to form a polymeric membrane with thedifferent chemical structure during the drying and make the chemical structureof derived polymeric membranes change in different ways during the laterpreoxidation and carbonization. Compared with refrigeration drying, thefreezing drying weakened decomposition reaction and promoted condensationreaction during preoxidation and carbonization. As a result, the frozenmembrane exhibited a better gas separation performance with a good flexilitydue to its dense microstructure. The freezing drying was the optimum way toprepare PPESK carbon membranes using CHCl₃ as solvent.

The dissolved organic carbon in natural water was mainly from soluble humicacid(HA) which had much harms in industrial and drinkablewater. As a new adsorbent, the multi-walled carbon nanotubes (MCNTs) were used toremove HA at different pH value, different MCNTs dosages and different HA initialconcentration, a series of experiments including batch adsorption, adsorptionisotherm were carried. The adsorption kinetics data was fittedwith pseudo-second-order rate model, their linear correlations was above 0.99,and equilibrium adsorptioncapacity obtained from fitting curve was 27mg/g, consistent with theexperimental results (25.5mg/g). The adsorption isotherm test was carried at 25℃-50℃, the equilibrium adsorptioncapacity was 29.7mg/g by Langmuir model, which was similar to theexperiment results. The free energy (Δ<>G), enthalpy(Δ<>H) and entropy(Δ<>S) were obtanined with Clapeyron-Clausius and Gibbs-Helmholtz equationin the adsorption isotherm, which all were negative, indicated that HA adsorbedby MCNT was an exothermic process of entropy reduction. MCNT’s outer surfaces,layer interspace,inner cavity and aggregated pores became efficient adsorption space for HA. Theπ-π interactionsbetween HA and MCNT played an important role in the adsorption process.

The BaTiO₃/Cu composite ceramics doped with Cuin the content range of 0-30 wt% were prepared by the solid-state reaction. Themicrostructure, percolation threshold and dielectric properties of ceramicswere investigated. The results show that the resistivity of BaTiO₃/Cucomposite ceramic increases with Cu content decreasing and the relationshipbetween them has a non-linear downward trend at the percolation threshold ( x=25wt%), then the composite isgradually changing from insulator into conductor. The value of ε_r of BaTiO₃/Cucomposites is raised with the increase of Cu content, and the maximal value is about9000 at 1 kHz at room temperature as Cu content of 30wt%. The dielectric lossof BaTiO₃/Cu composites increases with the increasing Cu doping, butthen decreased with the increasing frequency, which is due to the reducing ofthe amount of space charge. The temperature coefficient is less than 5% in the temperaturerange from 25℃to 115 ℃, and the dielectric constant is provided with hightemperature stability.

Si₃N₄ is apopular material with many excellent physicochemical properties. This presentwork make a comparative study on its low and high temperature phases (α- and β-Si₃N₄)by first-principles calculation based on density functional theory (DFT). Asfor α phase, the calculated lattice parameters are <>a=0.7678nm, <>c=0.5566nm;elastic- stiffness coefficients are c₁₁=4.232×10¹¹N/m², c₃₃=4.615×10¹¹N/m²; piezoelectric strain coefficients are <>d₃₃=0.402pC/N. While for β phase, they area=0.7536nm, c = 0.2874nm, c₁₁=4.241×10¹¹N/m², c₃₃=5.599×10¹¹N/m² and the piezoelectric strain coefficients are nearlyzero. The analysis shows that both α and β phases are high strength and highhardness, relating to their network structures of tetrahedron. Thepiezoelectricity is poor, especially for β-Si₃N₄. Thiscan be attributed to the structural symmetry, higher symmetry and lowerpiezoelectricity.

(1- x)Bi(Sc_{1- y}Y _y)O₃- xPbTiO₃(BSYPT- x/y) ceramics were prepared by theconventional mixed oxide method, and their crystal structure, microstructure, andferroelectric properties were investigated. XRD analyses show that the crystalstructure of BSYPT- x/y ceramicschanges from rhombohedral to tetragonal symmetry with increasing of PbTiO₃amount. The introduction of BiYO₃ into BiScO₃-PbTiO₃solid solution would cause a shift of morphotropic phase boundary (MPB) of BSYPT- x/y system from x=0.62, y=0.05 to x=0.56, y=0.20. The BYSPT- x/ y ceramics with x=0.58 and y=0.15 showthe pinched hysteresis loops, which can be attributed to the pinned domainwalls of the dipolar defects following the substitution of Sc³⁺ and Ti⁴⁺ions for Y³⁺ ions in B site of BYSPT system.

Two dimension needle-punched carbonfiber felts with an initial bulk density of 0.43 g/cm³ weredensified by isothermal-isobaric chemical vapor infiltration (ICVI) at 1050,1100, 1150℃and total pressure of 6kPa, using n-propanoldiluted by nitrogen as the precursor of pyrolytic carbon. The bulk density ofC/C composite after densified for 96h were 1.64 g/cm³, 1.68g/cm³and 1.69/cm³, respectively. Bulk densities of the infiltrated sampleswere determined as a function of infiltration time. The flexural strength wasinvestigated by three-point bending test. Texture and fracture surface morphologyof the samples were studied by polarized light microscope (PLM) and scanningelectron microscope (SEM). A layer of midium-textured carbon followed by alayer of high-textured carbon matrix were formed at 1050 and 1150 ℃. WhileC/C composites with pure high-textured pyrolytic carbon matrix was obtained at1100℃, with the flexural strength of 199.24MPa. No oxidationtrace was found on the surface of carbon fiber from PLM and SEM observation. Consequently,n-propanol is a promising precursor in CVI process for the densification of high-performanceC/C composites.

Carbon-carbon composites werefabricated in short period by LPIC (low pressure impregnation carbonization) processwith 225℃ air oxidation using mesophase pitch as precursor. The microstructureswere observed by PLM (polarizingmicroscope ). The bending property and fracture surface were tested byuniversaltesting machineand S EM (scanningelectron microscope), respectively. The results show that the carbon yield isimproved remarkably with 225℃ air oxidation compared withthe samples without air-oxidation. After four cycles of LPIC, the density of C/Ccomposites reaches 1.73 g/cm³. Its bending property is 152.39MPa, which is increased62.87% compared with the samples without air oxidation process. It is concludedthat the C/C composites with air oxidation exhibit pseudo-plastic failure behavior and the sampleswithout air-oxidation rupture from interlays with low bending strength.The microstructures of C/C composites without air oxidation are mainlysmall domains with few mosaic and domain textures. Nevertheless, the composites with 225 ℃ air oxidationpresent domain textures mainly with small domain and flow domain.

With the size of 1-2μm MoSi₂powder as raw material, MoSi₂ powderideal for air plasma spraying was prepared by spray drying and vacuumsintering. By using MoSi₂ powders (9.68μm ) and agglomeration powders (38-72μm) as the spray feedstock, MoSi₂ coatings weresuccessfully prepared using air plasma spraying. The phase composition and microstructure of the coatingwere studied.The results show that the mobility and loosedensity of theagglomeration powders sintered at 1300℃ for 1h are 17.1s/50g and 2.1g/cm³, respectively. Compared with the unsintered powders, the mobility and loose density of the sintered agglomeration powders increaseby 57.0% and 46%, respectively. XRD patterns shows the main phasesare Mo and Mo₅Si₃ phases in the coating prepared by thepowders with the size of 9.68 μm.In case of spraying withagglomeration powders, the main phase of the dense coating is MoSi₂. The “mesh”microstructure of molybdenum-rich phase is produced in the coatingprepared by the agglomeration powders.

Hydrogenatedamorphous carbon (a-C:H) films were annealed in air, to investigate the effect of ambient temperatureon thestructure and properties of a-C:H films. After annealed at differenttemperatures, structure, composition and properties of a-C:H films wereinvestigated <>via Fourier transform infrared spectroscopy (FTIR), Raman spectroscope, X-ray photoelectronspectroscope (XPS), 3D surface profiler and ball-on-disk tribotester. Compared with the as-deposited film, thea-C:H film annealed at low temperature of 300℃ exhibits similar structure,with internal decreasing stress and notably improved tribological property. Comparatively,at elevated temperatures of 400℃ and 500℃, the annealed films present severe graphitization and oxidation, contributingto the deterioration of the tribological properties or even complete failure.Thus, the annealing temperature plays a significant role on the structure,composition and properties of a-C:H films.

Magnesiumhydroxide chloride hydrate (MHCH) nanowires are important polymer fillers andprecursors for one-dimensional nanostructures. Here a novel method waspresented to prepareMHCH nanowires using calcined dolomite as raw materials viaa hydrothermal approach. XRD, SEM, and FT-IR analyses indicate that theas-prepared MHCH is well crystallized Mg₁₀(OH)₁₈Cl₂?5H₂Onanowires with diameters of 50-120nm and length of several tens micrometers. The TG-DTA patterns of MHCH consistedof two steps and MHCH is at endothermic status during the whole heatingprocess. The molar ratio of (MgO+CaO) in calcined dolomite to MgCl₂( R) plays a key role to the structureand morphology of MHCH. The aspect ratio of MHCH nanowires decreases with theincreasing of R and Mg(OH)₂will be formed when R was greaterthan 0.5. The optimum R to prepareMHCH is between 0.025 and 0.075. This study will extend the potential applicationsof dolomite due to the extensive applications of MHCH.

The microstructures and the microwave dielectricproperties of the (1? x)(Mg_0.7Zn_0.3)TiO₃- xCa_0.61La_0.26TiO₃(MZT-CLT) ceramic system were investigated. The objective of the presentwork is to compensate for the negative temperature coefficient of resonantfrequency of (Mg_0.7Zn_0.3)TiO₃ by the additionof (Ca_0.61La_0.26)TiO₃. MZT-CLTceramics exhibited mixed phases of (Mg_0.7Zn_0.3)TiO₃as the main phase associated with minor phases of Ca_0.61La_0.26TiO₃ and (Mg_0.7Zn_0.3)Ti₂O₅.The microwave dielectric properties are strongly correlated with the sinteringtemperature and the composition. Very dense MZT-CLT ceramics were synthesizedby sintering at1275 ℃. When the samples were sintered at temperaturesabove1300 ℃, the evaporation of Zn resulted the decrease indensity and degradation in dielectric properties. With the increasing of x, the relative dielectric constant ( ε_r) of the ceramicsincreases and the product of quality factor and resonant frequency ( Q · f) decreases. The ε_r, Q· fand temperature coefficient of resonant frequency ( τ_f) of 0.87(Mg_0.7Zn_0.3)TiO₃-0.13Ca_0.61La_0.26TiO₃ceramic sintered at1275℃ are 26, 86000 GHz and -6×10 ^{- 6} /℃, respectively.