Key Engineering Materials Vols. 512-515

Abstract: Nano-sized manganese-doped zinc aluminate spinel (Zn1−xMnxAl2O4; x = 0–6.0 mol%) powder phosphors were prepared by the sol–gel process. Zinc chloride, aluminum isopropoxide, and manganese chloride were employed as precursors. The influences of manganese concentration and heat treatment conditions on the crystallization and photoluminescence of the phosphors were investigated. The dried powders were amorphous to X-ray powder diffraction (XRD) and the single-phase ZnAl2O4 spinel crystallite started to form at temperatures as low as 600oC. The crystallization of powder did not significantly affected by various manganese concentrations. On heating at 1000oC, the resulting powder phosphors had the average crystallite and primary particle sizes of around 20–25 and 20–30 nm, respectively, depending on the dopant content and heating time. Photoluminescence spectra exhibited strong green emission bands centered at 512 nm under an excitation wavelength of 458 nm. The luminescence efficiency has been investigated as a function of dopant content, heating temperature, heating time, and specific surface area of the powders.

Abstract: As a Kind of Most Common Used Photocatalyst, TiO₂ Nanomaterials Existing Disadvantages on Low Light Energy Utilization in Visible Light Range and Difficulty on Recycle. in Our Study, Different Proportions of Fe³⁺ and Fe²⁺ Ion Were Doped with Nano-Ti0₂ Particles in Structure of Rutile Type through Method of Chemical Precipitation. the Result Showed that Nano-Composites Formed by TiO₂ Coexist with Fe₃O₄, with the Average Size of the Composite Particles Nearly 20 Nm. the Photo-Catalyst Performances of the Composite Have Improved Largely, and so the Relatively Optimized Preparation Conditions Were Presented.

Abstract: Using titaniferous blast-furnace slag (44-70 wt %), quartz, boric acid, and borax as the main raw materials, composition selecting in the phase-separation region of the Na2O-CaO-Al2O3-B2O3 -SiO2-TiO2 system, the basic glasses were prepared through mixed batches and melted at 1200 oC, then TiO2 whiskers could be achieved by heat-treatment the glass samples. The phase and morphology of samples were analyzed by XRD and SEM. The results indicated: when the composition of samples were selected in the phase-separation region and the ratio of SiO2/ B2O3 was between 1.64-1.87, at 850 °C heat-treatment, the diameter of whiskers was about 0.5μ~1μ and the length-diameter ratio was more than 50.

Abstract: Lithium dizirconium phosphate (LiZr2(PO4)3) possesses good ionic conductivity owing to its unique framework structure and can be used as favorable anode material in Li-ion battery. LiZr2(PO4)3 is commonly prepared by solid phase reaction in which higher temperature is needed and pure LiZr2(PO4)3 without other phases is difficult to obtain in the final products. In this paper, low cost hydrothermal synthesis of pure (LiZr2(PO4)3) was studied. Effects of the hydrothermal conditions (molar ratios of Li+ to ZrOCl2, addition of HF, pH values of reaction system and hydrothermal temperatures) on the phase composition of the products were investigated. The results showed that pure LiZr2(PO4)3 was successfully prepared at lower temperature of 80°C for 24h with the addition of HF when the pH value was adjusted to 5.0 and the molar ratio of Li+ to ZrOCl2 was 0.5 with the concentration of ZrOCl2 as 0.6mol/L. The phases and purity of the final products were characterized by XRD analysis.

Abstract: Olivine LiFePO₄ and LiFePO₄-C composite cathode materials were prepared by microwave hydrothermal process using FeC₂O₄·2H₂O, NH₄H₂PO₄, LiOH·H₂O and acticarbon as source materials. The effect of acticarbon on the structure and charge-discharge property of LiFePO₄ crystallites was investigated. The as-prepared battery powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer(EDS). The charge-discharge behavior was investigated for the characterization of the electrochemical performances of the powder. Results show that the introduction of acticarbon will not change the LiFePO₄ crystal structure, but achieve more uniform and fine crystallites and result in better electrochemical performance. Initial discharge capacity of the as-prepared LiFePO₄ is 103.4 mAh·g^-1 at 0.1 C rate. The discharge capacity of LiFePO₄-C is 136.1 mAh·g^-1 at the first cycle and 133.9 mAh·g^-1 after 30 cycles at 0.1 C rate.

Abstract: Cadmium sulphide (CdS) crystallites were successfully prepared by a microwave hydrothermal (M–H) process using cadmium chloride (CdCl₂·H₂O) and sodium thiosulfate (Na₂S₂O₃·5H₂O) as source material with different Cd²⁺ concentration. The phase, composition, morphology and optical property of the obtained crystallites were characterized by X–ray diffraction (XRD), field–emission scanning electron microscopy (FE–SEM), transmission electron microscopy (TEM) and ultraviolet–visible spectrophotometer (UV–Vis). Results show that the crystalline structure of the prepared CdS crystallites changes regularly with the increase of Cd²⁺ concentration and the corresponding morphology of CdS crystallites transforms from tetrahedron to quasi-sphere. The quasi-spherical CdS is derived from the nanoparticles-assembly behavior. And with the increase of Cd²⁺ concentration, the decrease in CdS crystallite size is observed. Obvious blue–shift is detected in the UV–Vis absorption when Cd²⁺ concentration reaches 0.60 mol/L.

Abstract: V₂O₅ powders were successfully synthesized by the EDTA assistanced ultrasound sol-gel process using NH₄VO₃ and EDTA, NH₃•H₂O as raw materials. The synthesized activation energy and the influence of pH values and the calcination temperatures on the phases and microstructures of powders were particularly investigated. The precursor powders and the V₂O₅ powders were characterized by X-ray diffraction (XRD), fourier transform inelectron microscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry-thermal gravimetric (DSC-TG). Results show that the obtained products exhibit good crystallization under the conditions of pH=4, calcination temperature 400~500 °C and calcination time 0.5 h during the synthesizing process. The as-prepared V₂O₅ powders show preferred growth orientation along (001) plane at the pH=4. By DSC analysis, the ultrasonic cavitation result in the decrease in synthesized activation energy obviously than that was prepared without ultrasonic irradiation.

Abstract: The In₂Se₃/CuSe composite powders with the size in the range of 2-8µm for solar cell were successfully synthesized via using relatively simple solvothermal method at atmospheric pressure by the reaction between InCI₃.4H₂O, CuCI₂.2H₂O and Selenious acid and hydrazine hydrate in ethylene glycol.The influences of reaction temperature, reaction time, concentration of solution on the phase and morphology of In2Se3/CuSe composite powders were investigated. The phase and morphology of the products h_{Subscript text}ave been well studied by X-ray diffraction (XRD)and scanning electron microscope (S_{Subscript text}EM) techniques.The study revealed that under the conditions of solvothermal method at atmospheric pressure, relative pure In₂Se₃ and CuSe powder were synthesized at temperatures of 160°C and 100°C respectively. The In₂Se₃/CuSe of irregular flake composite powders with the average size of 2-8µm had been obtained.The morphology of the products can be controlled by adding different kinds of surfactants such as PVP (Polyvinylpyrrolidone), CTAB (Hexadecyl trimethyl ammonium Bromide) and so on.

Abstract: The intercalation of ethylenediamine (en) into SnS₂ was synthesised by hydrothermal reaction at the temperature of 180 °C.And then dispersed the intercalation compounds in N, N-dimethylformamide (DMF) by stirring 48h,getting a light yellow sol ,with the nature of uniform ,transparent and stable.Analysised the structural of the product by means of X-ray powder diffraction (XRD) .The morphology of sol was characterized by using of transmission electron microscopy (TEM).The UV-Vis spectrophotometer was utilized for the absorbance of the colloidal.The results show that en has been successfully inserted into the layer of tin disulphide,and the target products is of high purity and good crystal.The sol is of high stability and homogeneity, and have the strongest absorption at the Wavelength of 270nm.

Abstract: SnS powders were obtained by the microwave hydrothermal (M-H) systhesis technique using SnCl2•2H2O and CH3CSNH2 as precursors. By changing the M-H processing temperature, SnS crystallites with differernt sizes and morphologies could be achieved. The phase compositions, microstructures and optical properties of the-prepared SnS crystallites were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis spectroscopy and photoluminescence spectroscopy (PL). Results show that the SnS powders present a herzenbergite-type orthorhombic structure and free of secondary phases. FE-SEM images indicate that the composite crystals are stacked with smaller flake-like crystals. By UV-Vis spectra analysis, the optical band gap of SnS powders is about 1.48 eV, which shows a blue shift of 0.18 eV compared to the bulk SnS. A near-infrared photoluminescence (PL) emission (830 nm) at room temperature is verified for the SnS powders when exited by 551 nm wavelength.