ZnFe2O4 and ZnO-Zn1−xMxFe2O4+δ (M = Sm3+, Eu3+ and Ho3+): Synthesis,physical properties and high performance visible light induced photocatalytic degradation of malachite green

The present work reports the synthesis of ZnFe₂O₄ and ZnO-Zn_1-xM_xFe₂O_4+δ (Ln?=?Sm, Eu and Ho) nanomaterials by conventional solid state reactions between Ln₂O₃, Zn(NO₃)₂, Fe(NO₃)₃·9H₂O and/or FeCl₃·6H₂O raw materials at 800?°C for 10?h and 15?h. Stoichiometric and nonstoichiometric reactions were explored for the synthesis of ZnFe₂O₄. The two Fe sources (Fe(NO₃)₃ and FeCl₃) were used to study the proper raw material type for the synthesis of the ZnFe₂O₄. The synthesized nanomaterials were characterized by powder X-ray diffraction (PXRD) technique. Rietveld analysis showed that the obtained materials were crystallized well in cubic crystal system with the space group Fd3m and lattice parameters a?=?b?=?c?=?8.4?Å. The rietveld data showed that the purity of ZnFe₂O₄ was increased from 14% to 88% when the Fe source was changed from FeCl₃ to Fe(NO₃)₃ meanwhile the reaction time was changed from 10 to 15?h. However, the purity was increased to 96% when the stoichiometry of Zn:Fe was changed from 1:2 to 0.8:2 at 800?°C for 15?h. The PXRD data revealed that dopant ion type had a considerable influence on the crystal phase purity of the obtained materials. It was found that Yb₂O₃ decreased more the purity of the obtained target compared to the other dopant ions. Ultraviolet-visible spectra showed that the synthesized nanomaterials had strong light absorption in the visible light region. Photocatalytic performance of the as-synthesized ZnFe₂O₄ was investigated for the degradation of pollutant Malachite Green (MG) in aqueous solution under direct visible light irradiation. The degradation yield at the optimized condition (0.09?mL H₂O₂, 30?mg catalyst and 60?min) was 98%.     

α－Al_2O_3衬底上生长的GaN膜的光学性质

采用金属有机化学气相淀积（ＭＯＣＶＤ）方法生长了α－Ａｌ２Ｏ３衬底上外延的高质量的单晶ＧａＮ薄膜。Ｘ射线衍射光谱与喇曼散射光谱表征了ＧａＮ外延薄膜的单晶结构和单晶质量。透射光谱和光调制反射光谱定出了六角单晶ＧａＮ薄膜的直接带隙宽度和光学参数。     

Magnetic and antibacterial studies of sol-gel dip coated Ce doped TiO2 thin films: Influence of Ce contents

Ce-doped TiO₂ thin films were synthesized by sol-gel dip coating route to evaluate the effect of Ce doping percentage on properties of TiO₂. X-ray diffraction spectra revealed both anatase and brookite phases, and Ce doping favours the anatase–brookite transformation of TiO₂ films. The optical constants of the thin films were achieved by evaluating spectroscopic UV-VIS-NIR spectrophotometry data. The band gap of the Ce doped TiO₂ was reduced from ~3.93 eV to ~3.79 eV with an increase in Ce doping percentage. All films have shown ferromagnetic behaviors which increase with the increase in Ce content due to enhancement in the bound magnetic polaron. Higher Ce doping increases the oxygen vacancies and saturation magnetization. Boost magnetic properties stem from the generation of the interaction between the Ce ion and an oxygen vacancy. The study showed that the antimicrobial activity of Ce doped TiO₂ is ineffective. Hence doping of Ce can modify the properties of TiO₂ and are used in LEDs, magneto-optical devices and solar cells.     

Synthesis of dysprosium/Mn–Cu ferrite binary nanocomposite: Analysis of structural,morphological, dielectric,and optomagnetic properties

Manganese–copper ferrite (MCFO) and dysprosium (Dy)-doped manganese–copper ferrite nanocomposites (Mn_0.5Cu_0.5Dy_xFe_2−xO₄) (x = 0, 0.05, 0.10, and 0.15) were synthesized by sonochemical method. Crystal structure and the structural parameters of the MCFO were analyzed based on the doping concentration of Dy ion. It was observed that the average crystalline size of the synthesized nanocomposite decreases when the concentration of Dy increases. The existing spherical surface morphology of the MCFO and Dy-doped MCFO nanocomposites were obtained through scanning electron microscopy. In the UV spectrum, the pristine MCFO sample showed an absorbance peak at 743 nm whereas the absorbance values of Dy-doped ferrite nanocomposite considerably shifted (blue) toward a lower wavelength (231–222 nm). The dielectric parameters of all ferrite nanocomposites were studied in the frequency range of 100 Hz to 5 MHz. The dielectric spectrum revealed that dielectric constant and loss tangent decreased with increased doping concentration of Dy ion. The saturation magnetization also changed with Dy doping in MCFO. The impact of Dy on manganese–copper ferrite changed the optical, dielectric and magnetic properties of the prepared binary ferrite nanocomposite, which can be used for microwave-absorbing material applications.     

The optical properties of hand-woven carpet

Abstract

The reflectance spectra and color properties of yarn when used in carpet are different from its cross-sectional direction as the pile of hand-woven carpet. This paper presents a comprehensive study of reflectance spectra and color properties of the pile in longitudinal direction and hand-woven carpet. For this purpose, the wool yarns were dyed with madder as a natural dye in various concentrations from 10% to 100% on the weight of sample. In order to study of the optical properties of the pile of hand-woven carpet, the dyed yarns were used to weave the hand-woven carpet. The obtained results showed that the yarn in longitudinal direction is lighter than the pile of hand-woven carpet, and so, the color strength of hand-woven carpet is more than the color strength of yarn. The spectrophotometric properties of samples were also studied by Principal Component Analysis (PCA). The difference between reflectance spectra of yarn in longitudinal direction and reflectance spectra of the pile of hand-woven carpet was also shown by PCA results.     

纳米材料的电学、光学和光电性能及应用前景

简要介绍了纳米材料的电学性能以及单电子器件的基本原理和应用；纳米材料的光学性能和光电性能，高的光吸收系数和光致荧光现象可使其应用于敏感元件，由于其光电特性具有超快响应速度，可望在超快光电子器件中得到应用。     

Synthesis,characterization and investigation of the electrochemical hydrogen storage properties of CuO–CeO2 nanocomposites synthesized by green method

Pure CuO–CeO₂ nanocomposites were synthesized by simple thermal decomposition method in presence of various Cu salts as a copper source and fructose as a green capping agent. In this study, the effect of various parameters such as the type of copper sources, temperature and time of reaction on the morphology and the particles size were studied. The products were characterized via X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), N2 adsorption (BET), vibrating sample magnetometer (VSM), and infrared spectrum (FT-IR). The optical property of the nanocomposite was examined via UV–vis (DRS) spectroscopy and the band gap was calculated to 3 eV. Also, the hydrogen storage capacity of CuO–CeO₂ nanocomposites and CeO₂ nanoparticles were investigated via chronopotentiometry method for the first time. The discharge capacity of CeO₂ nanoparticles and CuO–CeO₂ nanocomposites in 1 mA current and 20 cycles obtained 2150 and 2450 mAh/g, respectively.     

Thermal decomposition synthesis,characterization and electrochemical hydrogen storage characteristics of Co3O4–CeO2 porous nanocomposite

Particle-like Co₃O₄–CeO₂ nanocomposite was synthesized via a facile thermal decomposition process in the presence of fructose as a green capping agent and ammonium cerium(IV) nitrate as Ce source. The effect of various parameters such as different cobalt sources, calcination temperature and time were investigated on the size and morphology of products. The transmission electron microscopy observations indicated that the synthesized products have a particle-like shape with an average diameter of 18–35 nm. For the first time, the electrochemical hydrogen storage performance of Co₃O₄–CeO₂ porous nanocomposite was investigated via chronopotentiometry method in aqueous KOH solution in this paper. The electrochemical measurements showed that this product has a good hydrogen storage capacity at room temperature. Its maximum discharge capacity was 5200 mAh/g after 20 cycles. Therefore, Co₃O₄–CeO₂ porous nanocomposite showed that it is a good candidate for electrochemical hydrogen storage.     

Synthesis of Silicon Dioxide Optical Films Mixed with Acrylic Series Monomers by Sol-gel Process

In this study, silicon dioxide (SiO₂) particles are mixed with acrylic series monomers (methyl metacrylate (MMA) and 2-hydroxyethyl methacrylate (2-HEMA)) by sol-gel process to prepare inorganic-organic hybrid materials for the optical film. The other optical film has the same composition and process as the above but tri(ethylene glycol) dimethacrylate (TEGDMA) is added.

An infrared spectrometer, differential scanning calorimeter, thermo gravimetric analysis, ultraviolet-visible spectrophotometer, and spectroscopic-ellipsometer have been used to explore the effect on optical, hardness, and thermal properties of the two series of thin films. TEGDMA used as a bonding resin in this study showed that not only a better hardness and thermal properties, but also maintain good optical properties in the SiO₂ hybrid materials by sol-gel process.     

Room-temperature densification of MgO bulk ceramics with dispersed nitride phosphor particles

Wave conversion materials with high thermal conductivity are necessary for high-power semiconductor lighting. Ceramics have higher thermal conductivity than existing matrices such as resin or glass in which phosphor particles are dispersed. However, the high densification of ceramics generally requires high-temperature sintering, which degrades and alters the phosphor particles. In this study, we aimed to achieve the high densification of MgO ceramics at room temperature. Applying high hydrostatic pressure with water addition improved the sample packing ratio and promoted the formation of Mg(OH)₂. As a result, the relative density was ≥95%. Additionally, various nitride phosphor particles (CaAlSiN₃:Eu²⁺, β-SiAlON:Eu²⁺, and α-SiAlON:Eu²⁺) were dispersed in the MgO matrix at room temperature without degrading the luminescence property. The thermal conductivity of the obtained sample was about 8 W m^?1K^?1, 40 times higher than that of the epoxy matrix.