Effects of annealing on nanocrystalline Bi2S3 thin films prepared by chemical bath deposition

Nanocrystalline Bi₂S₃ thin films are deposited on tin chloride treated glass substrate from the solution containing bismuth nitrate, triethanolamine (TEA) and thioacetamide (TAM) at a bath temperature 318 K. The prepared films are subsequently annealed at different temperatures for studying the effect of thermal treatment on the structural, surface morphology, optical and electrical properties of the films. The X-ray diffraction studies affirmed that the deposited films are orthorhombic structures with average crystallites size of 14 nm to 28 nm. The scanning electron microscopy (SEM) images revealed that the films comprise of grains of spherical shape of unequal size. It is also observed that the small particles aggregate together to form a larger cluster. The average grain sizes determined from the TEM images are smaller than the crystallites size obtained from the XRD studies. The optical band gap of the films has been estimated to be 2.24–2.05 eV for the as-prepared and annealed films, respectively. The electrical conductivity of the as prepared Bi₂S₃ films at room temperature is found to be in the order of 10⁻³ Ω⁻¹ m⁻¹.     

超高分子量聚乙烯高温环境抗冲击能力研究

为研究超高分子量聚乙烯纤维(UHMWPE)在高温环境下的热性能和力学特性,对不同高温处理1h后的UHMWPE进行了SEM、DSC以及XRD分析。结果表明:150℃处理后纤维表面和断面已失去原有结构,XRD衍射峰峰值明显降低;DSC结果显示,与高温试验前及其它高温处理后有2个较大的吸热峰不同,150℃处理的样品仅有1个吸热峰,且峰值较低。对纤维包覆成的CDF进行爆轰性能试验,结果表明150℃处理后的样品抗冲击强度严重下降,已不能满足CDF的要求。     

Elaboration and characterization of a KCl single crystal doped with nanocrystalsof a Sb2O3 semiconductor

Undoped and doped KCl single crystals have been successfully elaborated via the Czochralski（Cz） method.The effects of dopant Sb₂O₃ nanocrystals on structural and optical properties were investigated by a number of techniques,including X-ray diffraction（XRD）,scanning electron microscopy（SEM）,energy dispersive X-ray（EDAX） analysis,UV-visible and photoluminescence（PL） spectrophotometers.An XRD pattern of KCl:Sb₂O₃ reveals that the Sb₂O₃ nanocrystals are in the well-crystalline orthorhombic phase.The broadening of diffraction peaks indicated the presence of a Sb₂O₃ semiconductor in the nanometer size regime.The shift of absorption and PL peaks is observed near 334 nm and 360 nm respectively due to the quantum confinement effect in Sb₂O₃ nanocrystals.Particle sizes calculated from XRD studies agree fairly well with those estimated from optical studies.An SEM image of the surface KCl:Sb₂O₃ single crystal shows large quasi-spherical of Sb₂O₃ crystallites scattered on the surface.The elemental analysis from EDAX demonstrates that the KCl:Sb₂O₃ single crystal is slightly rich in oxygen and a source of excessive quantities of oxygen is discussed.     

尖晶石相ZnCr_2O_4陶瓷生成条件

用 XRD法研究配料粒度、烧结温度及陈化处理诸因素对生成尖晶石相 Zn Cr2 O4数量的影响 ,结果表明 ,在 80 0～ 110 0℃间 ,原料的陈化处理可促进尖晶石相 Zn Cr2 O4的生成。     

Effect of 80 MeV Au ions irradiation on CuInTe2 single crystals grown by CVT technique

Single crystals of CuInTe₂ (CIT) have been grown by the chemical vapor transport (CVT) technique using iodine as the transporting agent. CIT crystals were irradiated with 80 MeV Au⁸⁺ ions at room temperature at different fluences. The surface roughness was measured using an atomic force microscope (AFM). It was found to increase from 9.319 nm in the as-grown sample to 61.169 nm in the sample irradiated with a fluence of 1×10¹³ ions/cm². The intensities of the X-ray diffraction peaks corresponding to the (112) and (004/200) planes of the irradiated sample decrease with respect to the fluences. The full-width at half-maximum (FWHM) of X-ray rocking curves was measured as a function of different ion fluences. The FWHW increases with increase of ions fluences. This is attributed to the irradiation-induced partial amorphization of the top surface of the CIT crystals. The fall in absorption coefficients with photon energy is sharper for as-grown samples than irradiated samples. The band gap value gradually decreases from 1.04 to 0.977 eV upon Au⁸⁺ ions’ irradiation with a fluence of 1×10¹³ ions/cm². Photoluminescence (PL) measurements show a red shift compared to the as-grown CIT single crystals. The Raman modes of A₁ (high) and E and/or B₂ (LO) are observed at 123 and 173 cm⁻¹ in as-grown CIT single crystals, respectively. As the ion fluence is increased, the Raman frequency increases and the curves broaden. The above observed features are related to the large electronic energy transfer of the Au beam to the CIT crystals.     

Facile deposition of ZnO:Cu films: Structural and optical characterization

Sol–gel technology has been applied for preparation of ZnO:Cu films. The proposed facile approach allows obtaining a wide variety of copper doped zinc oxide systems, revealing different structural and optical behaviors. The work presents structural and optical studies depending on Cu concentration and thermal treatments in the range of 500–800 °C. The structural analysis is performed by X-Ray diffraction (XRD). It reveals that small Cu addition enhances the film crystallization. Increasing copper concentration results in deterioration of ZnO:Cu crystallization. XRD study manifests no Cu oxide phases in ZnO:Cu film structure for lower Cu additions. For a specific higher copper concentration, an appearance of a small fraction of copper oxide is detected. Vibrational properties have been characterized by FTIR spectroscopy. The effect of the copper introduction into ZnO reveals a slight change of optical properties compared to ZnO films for certain Cu ratios. ZnO:Cu films with higher copper contents manifest different optical behaviors with very high transparency in spectral visible range.     

Investigations on the nanostructures of GaN,InN and InxGa1−xN

A controllable approach to the formation of III- nitride nanocrystalline structures using hydrothermal assisted method is presented. The structural and morphological properties of the prepared nanostructures are analyzed using X-ray diffraction, Fast Fourier Transformation and transmission electron microscope techniques. The temperature dependent structural formation of nitride nanostructures have been systematically investigated using X-ray diffraction. Raman spectra of the samples grown at optimized condition exhibited different phonon modes of the respective nitrides (GaN, InN and In_xGa_1−xN). Nanoparticles and nanorods formation of the indium nitride and indium gallium nitride are observed in the TEM micrographs. FFT analysis revealed that the synthesized III-nitride nanostructures are of good crystalline quality. Nanorods of these nitrides showed better crystalline quality than the nanoparticles in the FFT reflections.     

烧结温度对漂珠/ZrO2多孔轻质材料性能的影响

以漂珠为成孔材料,以ZrO2为结合剂,采用凝胶注模的方法制备出多孔轻质材料。通过分析材料的微观形貌、物相组成、显气孔率、体积密度、抗弯强度等性能参数,研究了烧结温度1200℃~1500℃对材料性能的影响。结果得出,烧结温度达到1400℃时,漂珠外壳与氧化锆的界面结合不再明显,ZrO2颗粒由点接触扩展到面接触;烧结温度1400℃的试样中锆英石的峰最强,说明漂珠和氧化锆已烧结熔融;1400℃下制备试样的显气孔率最大(68%),体积收缩率(20.8%)最低,而抗弯强度可达7.5MPa;烧结温度控制在1400℃,可使材料处于烧结中期,保证材料的各项性能满足其应用需求。     

Synthesis and characterization of Manganese doped Tungsten oxide by Microwave irradiation method

The aim of this article is to synthesis tungsten oxide (WO₃) nanoparticle along with Manganese (3 wt% and 10 wt%) by Microwave irradiation method. The physical properties of the synthesized Manganese doped Tungsten oxide materials were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscope (TEM), UV-Diffuse Reflectance Spectroscopy, SEM-EDAX and Photoluminescence studies. The predominant peaks obtained in X-ray diffraction pattern reveal the crystalline nature of the nanoparticles and the structure belongs to Monoclinic for pure and Mn doped WO₃. FTIR analysis shows the presence of Tungsten and oxygen in the synthesis material and verified with EDAX. TEM analysis shows both pristine and Mn doped WO₃ nanopaticles. They are having spherical shaped morphology with average particle size from 35 to 40 nm. UV-DRS revealed that the bandgap energy for pure and Manganese doped WO₃ are discussed in this article. The Scanning Electron Microscope analysis shows the plate like morphology for pure WO₃ and the morphology were decreased by doping Manganese. The defects and oxygen deficiencies were analysed by photoluminescence spectroscopy.     

Nitrogen dioxide (NO2) sensing performance of p-polypyrrole/n-tungsten oxide hybrid nanocomposites at room temperature

Polypyrrole (PPy)–tungsten oxide (WO₃) hybrid nanocomposite have been successfully synthesized using different weight percentages of tungsten oxide (10–50%) dispersed in polypyrrole matrix by solid state synthesis method. The sensor based on PPy–WO₃ was fabricated on glass substrate using cost effective spin coating method for detection of NO₂ gas in the low concentration range of 5–100 ppm. The gas sensing performance of hybrid material was studied and compared with those of pure PPy and WO₃. It was found that PPy–WO₃ hybrid nanocomposite sensor can complement the drawbacks of pure PPy and WO₃. The structure, morphology and surface composition properties of PPy–WO₃ hybrid nanocomposites were employed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The presence of WO₃ in PPy matrix and their interaction was confirmed using XRD, FTIR techniques. The porous surface morphology was observed with addition of WO₃ in PPy matrix which is useful morphology for gas sensing applications. TEM image of PPy–WO₃ hybrid nanocomposites shows the average diameter of 80–90 nm. X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical composition of nanocomposites. It was observed that 50% WO₃ loaded PPy sensor operating at room temperature exhibit maximum response of 61% towards 100 ppm of NO₂ gas and able to detect low concentration of 5 ppm NO₂ gas with reasonable response of 8%. The hybrid sensor shows better sensitivity, selectivity, reproducibility and stability compared to pure PPy and WO₃. The proposed sensing mechanism of hybrid nanocomposite in presence of air and NO₂ atmosphere was discussed with the help of energy band diagram. Furthermore, the interaction of NO₂ gas with PPy–WO₃ hybrid nanocomposites sensor was studied by cole–cole plot using impedance spectroscopy.