Transparent with wide band gap InZnO nano thin film: Preparation and characterizations

Novel indium zinc oxide (InZnO) thin film of 100 nm thickness was prepared onto pre-cleaned glass plate by thermal evaporation technique from InZnO nanoparticles. The metal oxide (In–O and Zn–O) bond and In, Zn and O elements present in the films were confirmed by Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy. The X-ray diffraction patterns revealed the mixed phase of cubic In₂O₃ and wurzite-hexagonal ZnO structure. SEM images showed smooth surface with uniform distribution of grains (201–240 nm) over the entire film surface. High transparency and low absorption obtained from optical study. The band gap energy was evaluated to be about 3.46–3.55 eV by Tauc’s plot. The structure, smooth surface and high transparency with wide band gap energy lead the thermally evaporated InZnO nano thin film to be used for transparent layer in optoelectronic devices in the future.     

Phase transition and related electronic and optical properties of crystalline phenanthrene: An ab initio investigation

This investigation discusses a structural phase transition of organic crystalline phenanthrene and the resulting changes of its electronic and optical properties investigated by ab initio calculations based on density functional theory (DFT). The structure of phase I has been optimized then its electronic and optical properties have been calculated. Our computational results on phase I (at ambient pressure) get along well with the available experimental data.Calculating the electronic and optical properties of phase II are proceeded in the same way and the results, particulary Raman spectra, reveal a crystallographic phase transition indicated by abrupt changes in lattice constants which are accompanied by rearrangement of the molecules. This results in modifications of the electronic structure and optical response. For both phases the band dispersion of the valence and conduction bands are anisotropic, whereas the band splitting is strongly noticeable in phase II. By calculating the imaginary part of the dielectric function of phase II, we have found the appearance of new peaks at the lowest z-polarized absorption and about 30 eV in all absorption components. Excitonic effects in the optical properties of phases I and II have been investigated by solving the Bethe–Salpeter equation (BSE) on the basis of the FPLAPW method. Phase II shows four main excitonic structures in the energy range below band gap, whereas phase I shows two. The excitonic structures in the optical spectra of phase II show a red shift in comparison to phase I. The calculated binding energies of spin-singlet excitons in phase II are larger than the ones in phase I.     

基于振动信号的深沟球轴承滚动体故障诊断研究

目前针对滚动轴承内、外圈故障的诊断方法较为有效,但难以诊断滚动体故障。针对这种情况,利用时域统计参数(有效值、峭度、脉冲因数、裕度因数)与Hilbert包络谱两种方法,对不同转速、负荷和故障程度情况下滚动体故障与正常状况的振动加速度数据进行比较分析,得出了滚动体故障难以诊断的原因,并给出了解决方法。     

Camphor sulfonic acid doped polyaniline-tin oxide hybrid nanocomposites: Synthesis,structural, morphological,optical and electrical transport properties

Camphor sulfonic acid (CSA) doped PANi–SnO₂ hybrid nanocomposites were synthesized by solid-state synthesis route with varying amounts (10–50%) of CSA. X-ray diffraction studies have proven the successful incorporation of CSA into the polyaniline–SnO₂ hybrid nanocomposites and the results are also supported by microstructural analysis. UV–visible and Fourier infrared spectroscopy studies have provided insight into the electronic interaction between the CSA, polyaniline, and SnO₂. The room temperature dc electrical conductivity of CSA-doped PANi–SnO₂ hybrid nanocomposite films were observed to depend on the amount of CSA doping and the morphology.     

Preparation and characterization of single crystalline In2O3 films deposited on MgO (110) substrates by MOCVD

Epitaxial indium oxide (In₂O₃) films have been prepared on MgO (110) substrates by metal-organic chemical vapor deposition (MOCVD). The deposition temperature varies from 500 °C to 700 °C. The films deposited at each temperature display a cube-on-cube orientation relation with respect to the substrate. The In₂O₃ film deposited at 600 °C exhibits the best crystalline quality. A clear epitaxial relationship of In₂O₃ (110)|MgO (110) with In₂O₃ [001]|MgO [001] has been observed from the interface area between the film and the substrate. The average transmittance of the prepared films in the visible range is over 95%. The band gap of the obtained In₂O₃ films is about 3.55–3.70 eV.     

Influence of metal ion concentration in the glycol mediated synthesis of Gd2O3:Eu nanophosphor

The solvothermal synthesis of highly luminescent and homogeneous Gd₂O₃:Eu³⁺ nanophosphor using diethylene glycol as medium, followed by controlled combustion with citric acid as fuel is reported. The influence of concentrations of carboxylic acid and metal cations on the structure, morphology and luminescence properties are investigated in detail. The microscopic investigations indicate the nanocrystalline nature and the strong influence of cation concentration on the size, shape and agglomeration of the particles. It is found that increase in concentration of metal cations lead to the reduction in agglomeration of nanophosphors. The large value of intensity parameter Ω_2, suggested that Eu³⁺ ions reside in a more asymmetric environment, resulted in intense emission due to ⁵D₀–⁷F₂ electric dipole transition. Emission decay analysis of the samples exhibited one exponential nature. The samples prepared under optimum conditions showed a quantum efficiency of 78.63% and a moderately high life time of 1.217 ms.     

Preparation of rare earth-doped ZnO hierarchical micro/nanospheres and their enhanced photocatalytic activity under visible light irradiation

Rare earth-doped ZnO hierarchical micro/nanospheres were prepared by a facile chemical precipitation method and characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV-visible diffuse reflectance spectroscopy and photoluminescence spectroscopy. The results showed that the as-synthesized products were well-crystalline and accumulated by large amount of interleaving nanosheets. It was also observed that the rare earth doping increased the visible light absorption ability of the catalysts and red shift for rare earth-doped ZnO products appeared when compared to pure ZnO. The photocatalytic studies revealed that all the rare earth-doped ZnO products exhibited excellent photocatalytic degradation of phenol compared with the pure ZnO and commercial TiO₂ under visible light irradiation. Nd-doped ZnO had the highest photocatalytic activity among all of the rare earth-doped ZnO products studied. The optimal Nd content was 2.0 at% under visible light irradiation. The enhanced photocatalytic performance of rare earth-doped ZnO products can be attributed to the increase in the rate of separation of photogenerated electron–hole pairs and hydroxyl radicals generation ability as evidenced by photoluminescence spectra.     

Drying dynamics of polymers films by an interferometric technique

We analyze a simple laser reflectivity measurement as a tool to monitor the drying kinetics of transparent polymer films. The reflectivity signal of a laser beam at normal incidence shows oscillations due to interference arising from multiple reflection of the laser light within the drying film. We develop a model to interpret the reflectivity curves in terms of time evolving refractive indices at the top and bottom of the film. We present results of the drying kinetics of transparent alkyd films on a glass substrate of high refractive index. Data shows a clear hallmark indicating the evolution of the crosslinking process. From the reflectivity curves, the time evolution of the refractive indices at the top and bottom is obtained. Assuming a linear-gradient of the refractive index along the depth of the film the average refractive index and consequently the film thickness as a function of time are estimated. Clear features in the time evolution of the refractive indices and thickness, correlate well with qualitative “dust”, “touch” and “fingerprint” drying times. Additionally, we present some preliminary results for water based latex binders, where scattering of light is present, showing that this simple optical technique could be extended for studying latex film formation.     

光纤传感及其在管道监测中应用的研究进展

管道安全关系到人类生命和财产安全,及时掌握管道结构健康状态是确保管道安全运行的重要前提。光纤传感技术的不断发展,使其在各个领域得到广泛研究与应用,特别是为管道结构的安全监测提供了技术保障。介绍了分布式光纤传感、光纤光栅传感、阵列复用传感、以及光纤智能传感的基本原理及关键技术,对其性能和特点进行了对比分析。在此基础上,阐述了各种光纤传感技术在管道监测中的具体应用,包括管道结构监测、管道泄漏监测以及管道腐蚀监测。通过对传感技术的不同应用进行比较分析,总结了各传感技术应用的特点和进一步研究发展的方向,指出光纤传感技术在管道监测方面具有的巨大优势和广泛的应用前景。