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      Permanent link:
      https://www.ias.ac.in/article/fulltext/pram/067/01/0153-0162

    • Keywords

       

      Sodium cobaltate; metal-insulator transition; charge ordering; sodium modes; infrared spectroscopy

    • Abstract

       

      Nickel substitution at the cobalt site in Na0.75CoO2 induces an upturn in the resistivity on lowering the temperature, with the metal-to-insulator transition temperature (TMIT) increasing with the Ni content. Low temperature far infrared measurements on polycrystalline samples of Na0.75CoO2 and Na0.75Co0.95Ni0.05O2, the latter having TMIT ∼ 175 K, have been carried out. Dramatic changes in the Na mode frequencies, and relative intensities of the out-of-plane modes corresponding to the two Na sites are observed, coincident with the MIT in Na0.75Co0.95Ni0.05O2. It is argued that these changes are associated with a charge ordering of the CoO2 layer, associated with the metal-insulator transition.

    • Author Affiliations

       

      M Premila1 A Bharathi1 N Gayathri1 P Yasodha1 Y Hariharan1 C S Sundar1

      1. Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102, India
    • Dates

       
  • Pramana – Journal of Physics | News

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