• NRIPASREE NARAYANAN

      Articles written in Bulletin of Materials Science

    • Cation substitution induced blue-shift of optical band gap in nanocrystalline Zn$_{(1−x)}$Ca$_x$O thin films deposited by sol–gel dip coating technique

      NRIPASREE NARAYANAN N K DEEPAK

      More Details Abstract Fulltext PDF

      Transparent nanocrystalline Zn${(1−x)}$Ca$_{x}O ($0 ≤ x ≤ 0.20$) thin films were deposited on glass substrates by sol–gel dip coating method. The X-ray diffraction (XRD) pattern revealed the polycrystalline nature of the films withhexagonal wurtzite structure and confirmed the non-existence of the secondary phase corresponding to CaO indicating the monophasic nature of the deposited films. The crystallinity of the films deteriorated with higher dopant concentration due to the segregation or separation of dopant ions in grain boundaries. The lattice parameters and the unit cell volume increased to a higher Ca-dopant concentration. This was due to the successful incorporation of Ca2+ ions with larger ionic radius inthe host zinc oxide (ZnO) lattice. The optical transmittance spectra of the samples showed transmittances above 60% in thevisible spectral range and the absorption edge in the near ultra-violet region got blue-shifted with cation substitution. Theestimated optical energy gaps confirmed the band gap widening with increase in Ca-dopant concentration. The calculatedvalues increased from 3.30 eV for undoped ZnO to 3.73 eV for Zn0.8Ca0.2O thin films giving 13.03% enhancement in theenergy gap value due to the electronic perturbation caused by cation substitution as well as deterioration in crystallinity.

  • Bulletin of Materials Science | News

    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.