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      https://www.ias.ac.in/article/fulltext/pram/047/02/0151-0161

    • Keywords

       

      High pressure Raman spectroscopy; optical spectroscopy; potassium terbium molybdate; electronic transition; phase transition

    • Abstract

       

      Raman and optical absorption studies under pressure have been conducted on KTb(MoO4)2 up to 35.5 GPa. A phase transformation occurs at 2.7 GPa when the crystal is pressurized at ambient temperature in a hydrostatic pressure medium. The sample changes to a deep yellow color at the transition and visibly contracts in theα-axis direction. The color shifts to red on further pressure increase. The Raman spectral features and the X-ray powder pattern change abruptly at the transition indicating a structural change. The pressure-induced transition appears to be a property of the layer-type alkali rare earth dimolybdates. However, the color change at the transition in KTb(MoO4)2 is rather unusual and is attributed to a valence change in Tb initiated by the structural transition and consequent intervalence charge transfer between Tb and Mo.In situ high pressure X-ray diffraction data suggest that phase II could be orthorhombic with a unit cell having 3 to 4% smaller volume than that of phase I.

    • Author Affiliations

       

      A Jayaraman1 S K Sharma1 S Y Wang1 S R Shieh1 L C Ming1 S-W Cheong1 2

      1. Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, HI - 96822, USA
      2. Lucent Technology, Murray Hill, NJ - 07974, USA
    • Dates

       
  • Pramana – Journal of Physics | News

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