Preparation and Characterization of Tin Oxide Thin Films

Tin oxide (SnO) thin films were prepared onto glass substrates by thermal evaporation under vacuum. The substrate temperature was kept constant at 300 K during the film growth. The structural studies using transmission electron microscopy (TEM) analysis showed that the SnO thin films have a polycrystalline and tetragonal crystal structure with preferential orientation of (110) planes parallel to the substrate. Optical transmission and reflection spectra, at normal incidence, in the spectral range 300-1100 nm, are investigated. The optical properties of SnO thin films were determined. The optical energy band gap, Eg, has been estimated from the absorption coefficient values using Tauc’s procedure. It is found that the SnO thin films exhibit direct band gap

Preparation and Characterisation of Alumina Template Obtained by OneStep Anodization Method

The goal of this study was to obtain an alumina template (AAO) by one-step anodization method and to evaluate its optical properties correlated with the annealing temperature. AAO was obtained from two different media: sulphuric acid (1.5 M H2SO4) and oxalic acid (0.4 M H2C2O4) at a potential of 15 V and 40 V, respectively. AAO morphology and chemical composition had been investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The average pore diameters such as 20 nm for AAO obtained from H2SO4 and 40 nm from H2C2O4 were measured. The crystalline structures of AAO samples annealed at three different temperatures of 150 ºC, 300 ºC and 350 ºC were studied by Xray diffractometry (XRD). The effect of annealing temperature on the optical properties of AAO was studied by UV-VIS spectrophotometry

Copper Plating Corrosion Study in Certain Environments

Copper plating was performed on nickel substrate by means of the potentiostatic electrodeposition method from a sulphate electrolyte solution. The copper coatings morphology was studied by means of the optical and electronic scanning microscopy techniques. The uniform electrodeposited films have a thickness of about 15 µm measured in cross-section. The corrosion behaviours of nickel substrate and copper films in different corrosive environments were studied. The corrosion study was performed by means of the linear polarisation method in four acid environments: 0.5 M H2SO4, HCl, HNO3 and glacial CH3COOH. From the recorded Tafel curves it was possible to obtain some information about the corrosion rate and the polarization resistance. In order to confirm these results, the gravimetric parameter was calculated by means of the “mass loss” method. By means of the X-ray diffraction analysis, the crystallographic structure of the specimens before and after corrosion was revealed. By means of the spectrophotometer device, the optical properties of the specimens were analysed

Structural analysis, electronic and optical properties of the synthesized Sb2S3 nanowires with small band gap

We report a simple colloidal synthesis of two types of Sb2S3 nanowires with small band gap and high aspect ratio. Field-emission scanning electron and transmission electron microscopies confirmed formation of high aspect ratio Sb2S3 nanowires, separated in the form of bundles and coalesced with each other in long bars. Diffuse reflectance and absorption spectroscopies revealed that the optical band-gap energies of the synthesized nanowires separated in the form of bundles are 1.56 and 1.59 eV, and coalesced with each other in long bars are 1.36 and 1.28 eV, respectively. The structure refinement showed that Sb2S3 powders belong to the orthorhombic structure with space group Pnma (no. 62). It was found that Sb2S3 nanowires separated in the form of bundles predominantly grow along the [0 1 0] direction being in the needle-like shape. The nanowires coalesced with each other in long bars rise in the form of long bars, are ribbon-like in shape and have expressed {1 0 1} facets which grow along the [0 1 0] direction. No peaks in photoluminescence spectra were observed in the spectral range from 250 to 600 nm. In order to shed more light on the experimental results concerning the band-gap energies and, in the literature generally poorly investigated electronic properties of the synthesized material, we performed theoretical calculations of the electronic structure and optical properties of the Sb2S3 samples synthesized here. This was done on the basis of density functional theory with the generalized gradient approximation, and also with an improved version of the exchange potential suggested recently by Tran and Blaha. The main characteristic is the significant improvement of the band gap value