Preparation of CuInSe2 thin films by four-step process

A simple process for the deposition of CulnSe₂ thin films was described. The CulnSe₂ compound was prepared by selenization of Cu-In alloy precursors, which were electrodeposited at a constant current. The selenized precursors were compacted and then annealed. The films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results indicate that single-phase CulnSe₂ is formed at 250℃ and its crystallinity of this phase is improved as the annealing temperature rises. The losses of In occur in selenization process. The dense CulnSe₂ film with comparatively smooth surface can be obtained by compaction under the pressure of 200 MPa.     

Influence of post-annealing on the properties of Ta-doped In<Subscript>2</Subscript>O<Subscript>3</Subscript> transparent conductive films

Ta-doped In₂O₃ transparent conductive oxide films were deposited on glass substrates using radio-frequency (RF) sputtering at 300°C. The influence of post-annealing on the structural, morphologic, electrical and optical properties of the films was investigated using X-ray diffraction, field emission scanning electron microscopy, Hall measurements and optical transmission spectroscopy. The obtained films were polycrystalline with a cubic structure and were preferentially oriented in the (222) crystallographic direction. The lowest resistivity, 5.1×10⁻⁴ Ω cm, was obtained in the film annealed at 500°C, which is half of that of the un-annealed film (9.9×10⁻⁴ Ω cm). The average optical transmittance of the films was over 90%. The optical bandgap was found to decrease with increasing annealing temperature.     

Silicon field emission arrays coated with CN<Subscript>x</Subscript> thin films

Arrays of silicon micro-tips were made by etching the p-type (1 0 0) silicon wafers which had SiO₂ masks with alkaline solution. The density of the micro-tips is 2×10⁴ cm⁻². The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly. The CN_x thin film, with the thickness of 1.27 μm was deposited on the silicon micro-tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X-ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5%, N: 12.6% and O: 17.9%. The silicon arrays coated with CN_x thin films had shown a good field emission characterization. The emission current intensity reached 3.2 mA/cm² at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CN_x thin films are likely to be good field emission cathode. The preparation and the characterization of the samples were discussed in detail. Foundation item: Supported by the National Natural Science Foundation of China (19975035) Biography: Chen Ming an (1978-), male, Ph. D candidate, research direction: novel functional materials film and ion beam modification of materials.     

Electrodeposition and characterization of thermoelectric Bi<Subscript>2</Subscript>Se<Subscript>3</Subscript> thin films

Bi₂Se₃ thin films were electrochemically deposited on Ti and indium tin oxide-coated glass substrates, respectively, at room temperature, using Bi(NO₃)₃·5H₂O and SeO₂ as starting materials in diluted HNO₃ solution. A conventional three-electrode cell was used with a platinum sheet as a counter electrode, and a saturated calomel electrode was used as a reference electrode. The films were annealed in argon atmosphere. The influence of cold isostatic pressing before annealing on the microstructure and thermoelectric properties of the films was investigated. X-ray diffraction analysis indicates that the film grown on the indium tin oxide-coated glass substrate is pure rhombohedral Bi₂Se₃, and the film grown on the Ti substrate consists of both rhombohedral and orthorhombic Bi₂Se₃.     

Research on C<Subscript>3</Subscript>N<Subscript>4</Subscript> superhard compound thin film and its application

By combination of DC reactive magnetron sputtering with multiple arcplating, the alternating C₃N₄/TiN compound film is deposited onto HSS. The core level binding energy and the contents of carbon and nitrogen are characterized by X-ray photoelectron spectrum. X-ray diffraction (XRD) shows that compound thin film contains hard crystalline phases of α-C₃N₄ and β-C₃N₄. The Knoop microhardness in the load range of 50, 5–54, 1 GPa is measured. According to acoustic emission scratch test, the critical load values for the coatings on HSS substrates are in the range of 40–80 N. The metal coated with C₃N₄/TiN compound films has a great improvement in the resistance against corrosion. Many tests show that such a coating has a very high wearability. Compared with the uncoated and TiN coated tools, the C₃N₄/TiN coated tools have a much longer cutting life. Foundation item: Supported by the National Natural Science Foundation of China (19875037) Biography: Wu Da-we( (1941-), male, Professor, research direction; thin film and its application.     

Highly <Emphasis Type="Italic">C</Emphasis>-axis oriented LiNbO<Subscript>3</Subscript> thin film on amorphous SiO<Subscript>2</Subscript> buffer layer and its growth mechanism

LiNbO3 waveguiding films with highly C-axis orieatation and superior crystallographic quality have been deposited on the amorphous SiO2 buffer layer of Si wafer by pulsed laser deposition (PLD) technique. X-ray diffraction,high-resolution electron transmission microscopy and atomic force microscopy were applied to characterizing the quality and orientaion of LiNbO3 thin film, and the optimized depositioa coaditioas have been determined for C-axis oriented growth. LiNbO3 thin films on amorphous SiO2 buffer layer were composed of intimate arrangements of quadrangular single crystal domain (150 nm x 150 nm) with C-axis orientatioa, and displayed sharp interface structures. The measurements of prism coupling technique indicate that the laser can be coupled into the LiNbO3 film and TE and TM waveguiding modes were detected. In addition, the possible mechanism of oriented growth on amorphous buffer layer and “film-substrate effects“ were discussed briefly, which suggests that its growth mechanism is likely analogous to the Voimer model with characteristics of three-dimensional islands nucleation on the smooth crystal surface.     

Comparison between P25 and anatase-based TiO<Subscript>2</Subscript> quasi-solid state dye sensitized solar cells

Pure anatase TiO2 films have been made via hydration of titanium isopropoxide using a sol-gel tech-nique, while mixed TiO2 films which contained both anatase and rutile TiO2 were made from commercial P25 powder. Quasi-solid state dye-sensitized solar cells were fabricated with these two kinds of mesoporous films and a comparison study was carried out. The result showed that the open-circuit photovoltages （Voc） for both kinds of cells were essentially the same, whereas the short-circuit photo-currents （1sc） of the anatase-based cells were about 33% higher than that of the P25-based cells. The highest photocurrent intensity of the anatase-based cell was 6.12 mA/cm^2 and that of the P25-based cell was 4.60 mA/cm^2. Under an illumination with the light intensity of 30 mW/cm^2, the corresponding energy conversion efficiency was measured to be 7.07% and 6.89% for anatase-based cells and P25-based cells, respectively.     

Synthesis of the CuInSe2 thin film for solar cells using the electrodeposition technique and Taguchi method

The Taguchi method was used to obtain the optimum electrodeposition parameters for the synthesis of the CuInSe₂ thin film for solar cells. The parameters consist of annealing temperature, current density, CuCl₂ concentration, FeCl₃ concentration, H₂SeO₃ concentration, TEA amount, pH value, and deposition time. The experiments were carried out according to an L₁₈(2137) table An X-ray diffractometer (XRD) and a scanning electron microscope (SEM) were respectively used to analyze the phases and observe the microstructure and the grain size of the CuInSe₂ film before and after annealing treatment. The results showed that the CuInSe₂ phase was deposited with a preferred plane (112) parallel to the substrate surface. The optimum parameters are as follows: current density, 7 mA/cm 2 ; CuCl₂ concentration, 10 mM; FeCl₃ concentration, 50 mM; H₂SeO₃ concentration, 15 mM; TEA amount, 0 mL; pH value, 1.65; deposition time, 10 min; and annealing temperature, 500℃.     

Structural stability of C<Subscript>60</Subscript> films under the bombardment of 1.95 GeV Kr ions

The structural stability of C₆₀ films under the bombardment of 1.95 GeV Kr ions is investigated. The irradiated C₆₀ films were analyzed by Fourier Transform Infrared (FTIR) spectroscopy and Raman scattering technique. The analytical results indicate that the irradiation induced a decrease of icosahedral symmetry of C₆₀ molecule and damage of C₆₀ films; different vibration modes of C₆₀ molecule have different irradiation sensitivities; the mean efficient damage radius obtained from experimental data is about 1.47 nm, which is in good agreement with thermal spike model prediction.     

Investigation of the deterioration of passive films in H<Subscript>2</Subscript>S-containing solutions

The effect of H₂S on the corrosion behavior of 316L stainless steel was investigated using electrochemical methods by changing the gas condition from CO₂ to H₂S and then back to CO₂. The presence of H₂S showed an acceleration effect on the corrosion of 316L stainless steel in comparison with CO₂. The acceleration effect remained even after the complete removal of H₂S by CO₂, indicating that the passive film was irreversibly damaged. X-ray photoelectron spectroscopy (XPS) analysis indicated that the passive film was composed of Cr₂O₃, Fe₂O₃, and FeS₂ after being immersed in H₂S-containing solutions. The semiconducting property of the passive film was then investigated by using the Mott-Schottky approach. The presence of sulfides resulted in higher acceptor and donor densities and thus was responsible for the deterioration of passive films.     

Micro-arc oxidization fabrication and ethanol sensing performance of Fe-doped TiO<Subscript>2</Subscript> thin films

In-situ pure TiO₂ and Fe-doped TiO₂ thin films were synthesized on Ti plates via the micro-arc oxidation (MAO) technique. The as-fabricated anatase TiO₂ thin film-based conductometric sensors were employed to measure the gas sensitivity to ethanol. The results showed that Fe ions could be easily introduced into the MAO-TiO₂ thin films by adding precursor K₄(FeCN)₆·3H₂O into the Na₃PO₄ electrolyte. The amount of doped Fe ions increased almost linearly with the concentration of K₄(FeCN)₆·3H₂O increasing, eventually affecting the ethanol sensing performances of TiO₂ thin films. It was found that the enhanced sensor signals obtained had an optimal concentration of Fe dopant (1.28at%), by which the maximal gas sensor signal to 1000 ppm ethanol was estimated to be 7.91 at 275°C. The response time was generally reduced by doped Fe ions, which could be ascribed to the increase of oxygen vacancies caused by Fe³⁺ substituting for Ti⁴⁺.     

Preparation and optical properties of solid solution semiconductor (Zn x Cd1−x S) doped silica glasses

Semiconductor(Zn_xCd_1−x S) doped silica glasses were prepared by Sol-Gel process andin situ growth technique. The structure of the materials was characterized by X-ray diffraction technique, the particle size of semiconductor crystallites from X-ray patterns was estimated less than 10 nm. From absorption spectra, it is obtained that the absorption edges shifted to short wavelength direction when Zn contents increased, and the absorption edge can be adjusted from 2.46 eV to 2.96 eV by controlling Zn contents. The third-order nonlinear optical susceptibility was studied at 532 nm with 8 ns pulse laser by degenerate four wave mixing (DFWM) technique.     

双源法制备CuInSe2多晶薄膜的研究

利用氮气作保护气体，用元素合成法进行开管烧结，合成具有单一相黄铜矿结构的CuInSe     

TiO<Subscript>2</Subscript>@MgO core-shell film: Fabrication and application to dye-sensitized solar cells

In this study,TiO2@MgO core-shell film was obtained by using a simple chemical bath deposition method to coat a thin MgO film around TiO2 nanoparticles. The core-shell configuration was characterized by X-ray diffractometer (XRD),scanning elec-tron microscopy (SEM),energy dispersive X-ray spectroscopy (EDX),and high-resolution transmission electron microscopy (HRTEM). Lattice fringes were observed for the TiO2 particles,and the MgO shell showed an amorphous structure,revealing a clear distinction between the core and shell materials. Applying the core-shell film as photoanode to the dye-sensitized solar cells (DSSCs),it shows a superior performance compared to the pure TiO2 electrode. Under the illumination of simulated sunlight (75 mW-cm-2),the short circuit photocurrent (Jsc),the open circuit photovoltage (Voc),and the fill factor (fF) are 8.80 mA-cm-2,646 mV,and 0.69,respectively,and the conversion efficiency (η) in-creased by 21.8% (from 4.32% to 5.26%) when dipping for opti-mum condition.     

Investigation of the cross-reaction mechanism of C<Subscript>6</Subscript>H<Subscript>5</Subscript>F-HNO<Subscript>2</Subscript> aqueous solution irradiated at 355 nm by transient absorbance spectrum technique

The transient absorption spectrum technique was employed to investigate the cross-reaction mechanism of C6H5F-HNO2 aqueous solution irradiated at 355 nm. The characteristic and the kinetic parameters of transient species were also detected. Hydroxyl radical derived from the photolysis of HNO2 was added to monofluorobenzene with a second-order rate constant of （5.83±0.17）×10^9 L·mol^-1·s^-1 to form an adduct, C6H5F…OH, which was able to react with HNO2 as the main reaction pathway with a rate constant of （8.3±0.1）×10^7 L·mol^-1·s^-1. The C6F6…OH adduct can also be decayed by elimination of H2O to yield monofluorophenyl radical C6H4F-. By GC-MS technique, the final products were identified to be monofluorophenol, nitro-monofluorobenzene, nitro-monofluorophenol and para-fluorobiphenyl.     

Giant magneto-optical faraday effect of nanometer Fe-In<Subscript>2</Subscript>O<Subscript>3</Subscript> granular films

The giant magneto-optical Faraday effect of nanometer ferromagnetic metal-semiconductor matrix Fe-ln2O3 granular films prepared by the radio frequency sputtering are studied. The result shows that the Faraday rotation angle θF value of the granular film samples with Fe volume fraction x = 35% is of the order of 10^5（°）/cm at room temperature. Temperature dependence of the Faraday rotation angle θF of Fe0.35（In2O3）0.65 granular films shows that θF value below 10 K increases rapidly with the decrease of the temperature, and when T= 4.2 K, θF value is 106（°）/cm. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that when the temperature decreases to a critical point Tp = 10 K, the transformation of state from ferro-agnetic to spin-glass-like occurs in Fe0.35（In2O3）0.65 granular films. The remarkable increase of the Faraday rotation angle θF value of Fe0.35（In2O3）0.65 granular films below 10 K seems to arise from the sp-d exchange interaction of the granular film samples in the spin-glass-like state.     

CaCO<Subscript>3</Subscript> film synthesis from ladle furnace slag: morphological change,new material properties,and Ca extraction efficiency

A rapidly air-cooled ladle furnace slag (RA-LFS), which is a type of steelmaking slag discharged from a steel mill, was used to synthesize CaCO₃ film. The CaCO₃ film with 35 cm2 of surface area was synthesized under atmospheric conditions, and the surface morphology of the CaCO₃ films was changed by using additives (CaCl₂ and ethylene glycol). Especially, the addition of CaCl₂ changed the surface morphology of CaCO₃ film with pore and induced new material properties, such as water adsorption. The (012) face of CaCO₃ film (calcite) was rapidly decreased by the addition of CaCl₂. The major components of RA-LFS were calcium (type of CaO, 53.9wt%) and aluminum (type of Al₂O₃, 37.9wt%), and the major crystal phases of RA-LFS were C₃S, C₁₂A₇, and C₃A. The calcium extraction efficiency of RA-LFS was significantly increased after the CaCO₃ film synthesis. The material properties (hardness and elastic modulus) and the thermal characteristics of the CaCO₃ films were analyzed by nano-indentation and thermogravimetry-differential thermal analysis. The synthesized CaCO₃ films from RA-LFS and Ca(OH)₂ (reagent) showed similarities in terms of their material properties and the decomposition temperature.     

Effects of silty sand on CO<Subscript>2</Subscript> corrosion behavior of low-Cr tubing steel

An experimental study was carried out to assess the effects of silty sand on the CO 2 corrosion behavior of 1 wt% Cr (1Cr) and 3 wt% Cr (3Cr) tubing steel under 0.5 MPa CO 2 at 100°C and 1.5 m/s flow velocity.The 1Cr and 3Cr specimens both suffered general corrosion,but the surface was coarser in the pure CO 2 corrosion environment.Under silty sand conditions,severe pitting corrosion occurred on the 1Cr specimens and some acicular pitting appeared on the 3Cr specimens.The average corrosion rates of 1Cr and 3Cr steels increased by factors of 3 and 1.6,respectively.The corrosion products were analyzed by scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS),X-ray diffraction (XRD),and electrical impedance spectroscopy (EIS).The results show that silty sand acts as an inclusion in corrosion product films and reduces the homogeneity and density of the products,rather than abrading the corrosion film.Ion-diffusion channels may build up around the irregular silty sand;this would degrade the protective capabilities of the product films and aggravate corrosion.     

Preparation and radar-absorbing properties of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiO<Subscript>2</Subscript>/Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/Yb<Subscript>2</Subscript>O<Subscript>3</Subscript> composite powder

Al₂O₃/TiO₂/Fe₂O₃/Yb₂O₃ composite powder was synthesized via the sol-gel method. The structure, morphology, and radar-absorption properties of the composite powder were characterized by transmission electron microscopy, X-ray diffraction analysis and RF impedance analysis. The results show that two types of particles exist in the composite powder. One is irregular flakes (100-200 nm) and the other is spherical Al₂O₃ particles (smaller than 80 nm). Electromagnetic wave attenuation is mostly achieved by dielectric loss. The maximum value of the dissipation factor reaches 0.76 (at 15.68 GHz) in the frequency range of 2-18 GHz. The electromagnetic absorption of waves covers 2-18 GHz with the matching thicknesses of 1.5-4.5 mm. The absorption peak shifts to the lower-frequency area with increasing matching thickness. The effective absorption band covers the frequency range of 2.16-9.76 GHz, and the maximum absorption peak reaches -20.18 dB with a matching thickness of 3.5 mm at a frequency of 3.52 GHz.     

Development and characterization of interspecific hybrids between <Emphasis Type="Italic">Oryza sativa</Emphasis> and <Subscript>O. latifolia</Subscript> by <Subscript>in situ</Subscript> hybridization

Oryza sativa and O. latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, interspecific hybrids of these species were obtained using the embryo rescue technique. Hybrid panicle traits, such as long awns, small grain, exoteric large purple stigma, grain shattering and dispersed panicles, resemble that of the paternal parent, O. latifolia, whereas there is obvious heterosis in such respects as plant height, tillering ability and vegetative vigor. Chromosome pairing and the genomic components of the hybrid were subsequently investigated using genomic in situ hybridization （GISH） and fluorescent in situ hybridization （FISH） analysis. Based on the mitotic metaphase chromosome numbers of the root tips investigated, the hybrid is a triploid with 36 chromosomes. The genomic constitution of the hybrid is ACD. In the meiotic metaphase Ⅰ of the hybrid pollen mother cell, poor chromosome pairing was identified and most of the chromosomes were univalent, which resulted in complete male sterility in the hybrid.