Browsing by Author "Nayar, VU"

Now showing 1 - 9 of 9
  • Item
    Effect of thermal annealing on the structural and optical properties of nano structured zinc oxide thin films prepared by pulsed laser ablation
    (Solar Energy Materials & Solar Cells, 2009) Vinodkumar, R; Lethy, KJ; Beena, D; Satyanarayana, M; Jayasree, RS; Ganesan, V; Nayar, VU; Mahadevan Pillai, VP
  • Item
    Effect of thermal annealing on the structural and optical properties of nanostructured zinc oxide thin films prepared by pulsed laser ablation
    (SOLAR ENERGY MATERIALS AND SOLAR CELLS, 2009) Vinodkumar, R; Lethy, KJ; Beena, D; Satyanarayana, M; Jayasree, RS; Ganesan, V; Nayar, VU; Pillai, VPM
    Zinc oxide (ZnO) films are prepared by pulsed laser ablation, on an optically flat quartz substrate for different deposition time. The influence of annealing temperature, on the structural and optical properties of ZnO films is investigated systematically using X-ray diffraction (XRD), energy dispersive Xray analysis (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectra, UV-vis spectroscopy and photoluminescence spectroscopy (PL). The XRD pattern shows that the as-deposited films are amorphous and the annealed films are polycrystalline. The average size of the crystalline grains varies from 9 to 26 nm in the films. The SEM and AFM images reveal uniform distribution of grains in the films and the grains are in the nanoscale dimension. Raman spectra suggest the hexagonal wurtzite phase for the ZnO films. The UV-visible spectra show an increase in transmittance with annealing temperature. The observation of very intense PL emission from the films annealed at 773 K, suggest the suitability of these films for applications as light emitters in the visible region. The ability to produce the stochiometric ZnO thin films with reproducible structural, morphological and optical characteristics should be useful as a suitable window material for practical industrial solar cell and display devices. (C) 2008 Elsevier B.V. All rights reserved.
  • Item
    Infrared and polarised Raman spectra of tetramethyl ammonium Cerium (III) Bis (sulfate) trihydrate
    (J Solid State Chem., 1996) Jayasree, RS; Nayar, VU; Jordanovska, V
  • Item
    Infrared and polarized Raman spectra of RbAl (SO4)2.12H2O
    (J Solid State Chem., 1996) Suresh, G; Ratheesh, R; Jayasree, RS; Nayar, VU; Keresztury, G
  • Item
    Raman and infrared spectral analysis of corrosion products on zinc NaZn4Cl(OH)(6)SO4-6H(2)O and Zn4Cl2(OH)(4)SO4 center dot 5H(2)O
    (MATERIALS CHEMISTRY AND PHYSICS, 2006) Jayasree, RS; Pillai, VPM; Nayar, VU; Odnevall, I; Keresztury, G
    Two corrosion products of zinc namely NaZn4Cl(OH)(6)SO4 center dot 6H(2)O which occurs mainly in marine and traffic environments and Zn4Cl2(OH)(4)SO4 center dot 5H(2)O which occurs in industrial, rural and urban environments were analysed using infrared and Raman spectroscopic methods and the vibrational modes of SO42- ion, OH radical and H2O molecules have been identified and discussed. The symmetric stretching vibrations of the SO42- ion of the compounds give an indication of the distorted structure for the SO4 anion in the compounds, the distortion being more in Zn4Cl2(OH)(4)SO4 center dot 5H(2)O. Due to the presence of strong hydrogen bond network, an unusual lowering of the symmetric stretching mode of SO4 is observed in both the compounds. In NaZn4Cl(OH)(6)SO4 center dot 6H(2)O, medium to weak hydrogen bonding network is present while strong to weak hydrogen bonding is present in Zn4Cl2(OH)(4)SO4 center dot 5H(2)O. (c) 2005 Elsevier B.V. All rights reserved.
  • Item
    Raman and Infrared spectral analysis of corrosion Products on Zinc NaZn4Cl(OH)6 SO46H2O and Zn4Cl2(OH)4 SO4 5H2O
    (Materials Chemistry and Physics, 2006) Jayasree, RS; Mahadevan Pillai, VP; Nayar, VU; Odnevall, I; Keresztury, G
  • Item
    Spectroscopic and thermal analysis of a submandibular sialolith of Wharton's duct resected using Nd:YAG laser
    (Lasers Med Sci., 2008) Jayasree, RS; Gupta, AK; Vivek, V; Nayar, VU
  • Item
    Temperature dependent Raman spectra of nona aqua lanthanoid (Pr) single crystal
    (Spectrochim Acta, 2006) Jayasree, RS; Bushiri, MJ; John, A; Nayar, VU
  • Item
    Temperature dependent polarized Raman spectra of nonaaqualanthanoid (Pr) single crystal
    (SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 2006)
    Polarized Raman spectral changes with respect to temperature were investigated for Pr(BrO3)(3)center dot 9H(2)O single crystals. FTIR spectra of hydrated and deuterated analogues were also recorded and analysed. Temperature dependent Raman spectral variation have been explained with the help of the thermograms recorded for the crystal. Factor group analysis could propose the appearance of BrO3 ions at sites corresponding to C-3v (4) and D-3h (2). Analysis of the vibrational bands at room temperature confirms a distorted C3v symmetry for the BrO3 ion in the crystal. From the vibrations of water molecules, hydrogen bonds of varying strengths have also been identified in the crystal. The appearance v(1) mode of BrO3- anion at lower wavenumber region is attributed to the attachment of hydrogen atoms to the BrO3 anion. At high temperatures, structural rearrangement is taking place for both H2O molecule and BrO3 ions leading to the loss of water molecules and structural reorientation of bromate ions causing phase transition of the crystal at the temperature of 447 K. (c) 2005 Elsevier B.V. All rights reserved.