A. Albert Irudayaraj

Influence of nitrogen flow rate on growth of TiAlN films prepared by DC magnetron sputtering

Abstract Thin films of TiAlN were deposited on (111) oriented silicon single crystal substrates from a composite Ti–Al target by DC reactive magnetron sputtering at 773 K under various N2 flow rates. Substantial influence of N2 flow rate on the rate of deposition, grain size, crystallinity, composition, hardness and resistivity was observed. While the deposition rate, grain size and the ratio of concentration of Ti to Al of the deposited TiAlN films decreased with increasing N2 flow rate, the resistivity of the films increased with increasing N2 flow rate.

Structural properties and electrical resistivity of TiNx and Ti1−xAlxN films prepared by reactive dc magnetron sputtering: effect of nitrogen flowrate

Abstract Nanocrystalline thin films of titanium nitride and titanium aluminium nitride were deposited on (111) Si substrates by reactive dc magnetron sputtering under various nitrogen flowrates and at constant substrate temperature. The effect of nitrogen flowrate on the structural and electrical properties of TiNx and Ti1−xAlxN thin films deposited at substrate temperatures of 973 and 773 K respectively is investigated. TiNx films are polycrystalline at all N2 flowrates and there is a change of preferred orientation from (200) to (111) with increasing nitrogen flowrates. In contrast, Ti1−xAlxN thin films are polycrystalline only at low nitrogen flowrates (<5 sccm) and show a tendency to become more nanocrystalline with weak (200) preferred orientation at higher nitrogen flowrates. The variation of lattice parameter showed opposite behaviour in these two types of films. Auger electron spectroscopy indicated that the nitrogen concentration of both types of the films gradually increased with increasing nitrogen flowrate and almost reached a constant value at a flowrate of nitrogen ≥5 sccm. While the resistivity of TiNx films showed a minimum at a nitrogen flowrate of 5 sccm, the resistivity of Ti1−xAlxN films increased with increasing nitrogen flowrate. The variation in the electrical resistivity could be explained on the basis of structural changes occurring in these two types of films.

One step synthesis, optimization and growth mechanism carambola fruit shaped CuO nanostructures: electrochromic performance

Micro and nanostructures with well-defined shape have attracted great interest due to their novel properties and diverging applications. Herein the one step simple sonochemical method for the synthesis of carambola fruit shaped and spindle shaped semiconducting copper oxide nanostructures are described. The pH concentration and the reaction time have been varied in order to find the optimized condition in which spindle shaped and carambola fruit shaped CuO nanoparticles are obtained. Also the effect of pH and reaction time on the properties of CuO nanostructures have been investigated and reported. The possible growth mechanism for the carambola fruit shaped structures has also been discussed. The prepared samples have been characterized using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and UV–visible spectrophotometry.

Investigation on the preparation and properties of nanostructured cerium oxide

Cerium oxide (CeO2) nanoparticles were successfully synthesized by the hydrothermal method with different reaction times. The synthesized CeO2 nanoparticles were characterized by Powder X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM), UV-Vis spectroscopy and FTIR spectroscopy. The effects of the reaction time on the structure and morphology of the prepared samples were investigated using XRD and SEM. The XRD studies reveal that the ceria nanoparticles have face-centered cubic structure. The SEM images reveal that the prepared Ceria nanoparticles are an aggregated form of spherical nanoparticles and the particle size decreases with increasing reaction time. FTIR analysis confirms the presence of CeO2 in the prepared samples. UV-Vis spectral studies show that the UV cut off wavelength decreases and the optical band gap increases with increased reaction time. Photoluminescence (PL) studies indicate that the PL emission of both the samples occurs at 683 nm, however, the emission intensity increases with longer reaction times.

Sensitivity Studies on Vacuum Deposited V2O5 Thin Films

Vanadium pentoxide thinfilms have been deposited by vacuum evaporation method and the effect of deposition temperatures on the surface morphology of the prepared sample has been analyzed. Structural and morphological were carried out on the prepared samples, using X-Ray Diffractometer (XRD) and Scanning Electron Microscopy (SEM). The samples deposited at elevated temperature showed nanopetal like structures on their surface which were found to be around 100-200 nm. The formation of the V2O5 phase has been confirmed through TG/DTA analysis which shows a sharp peak around 690°C corresponding to the melting point of vanadium pentoxide. The best sample was subjected to gas sensing analysis and the change in the resistance of the sensing element with respect to the test gas concentration was measured by noting down the resistance at each concentration for various time intervals. Sensitivity of the material linearly increased with different concentration of the test gas.

Comparative Study on the Properties of BTCS and BTCZS Crystals Grown by Slow Evaporation Method

Good quality Bisthiourea Cadmium Sulphate (BTCS) and Bisthiourea Cadmium Zinc Sulphate (BTCZS) crystals have been grown by simple slow evaporation method. The grown crystals were found to be transparent in the entire visible region. From the powder X-ray diffractograms it is concluded that BTCS crystal belongs to orthorhombic system, whereas BTCZS crystals belong to monoclinic system. From the FTIR comparative study of BTCS and BTCZS, it is observed that when Zinc is added into BTCS crystal, there is a decrease in the frequency of symmetric C=S stretching and an increase in the frequency of N-H asymmetric stretching vibration. UV-Vis studies show that the grown crystals have high transparency in entire visible region. The Vicker’s microhardness results show that the addition of Zinc with Bisthiourea Cadmium Sulphate reduces the hardness of the crystal.