A. Dhayal Raj

Gas Sensing Properties of Chemically Synthesized V2O5 Thin Films

Nanostructured vanadium pentoxide films have been synthesized by using a sol–gel technology from V2O5 powder and hydrogen peroxide. The V2O5 powder was dissolved in hydrogen peroxide solution, agitated and heated up to 65oC to form gel by the dissociation of the peroxide complexes. The obtained gel was deposited by dip coating technique and dried in air at room temperature. Structural, morphological and compositional analyses were carried out on the prepared samples using X-Ray Diffractometer (XRD), Raman spectrometer and scanning electron microscopy (SEM). The as-prepared films show an amorphous nature, while those annealed at 400oC exhibit orthorhombic structures. The films seem to have grain like structures on annealing which are expected to help the gas sensing properties of the V2O5 films. The annealed films were connected with copper electrodes and used as sensing element. 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. Sensitivity of the material linearly increased with different concentrations of ethanol and ammonia. It is clearly seen that the material has more sensing response for ethanol when compared to that of ammonia.

Synthesis of Vertical ZnO Nanorods on Glass Substrates by Simple Chemical Method

ZnO nanorods (NRs) have been synthesized by a chemical bath deposition (CBD) method on simple glass substrate that had been precoated by successive ionic layer absorption and reaction (SILAR) with a thin ZnO film. ZnO NR array was obtained by using zinc acetate and hexamethylenetetramine as aqueous solutions at optimized pH concentration and deposition time. X-ray diffraction (XRD) and SEM analysis were used to confirm the growth of ZnO nanorods. The pH and deposition time of the solution was found to influence the growth behavior of ZnO NRs. PL analysis also reflected the growth behavior of ZnO NRs.

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.