Pressure-induced structural and electronic transition in KTb(MoO4)2 through Raman and optical studies

A. Jayaraman, S. K. Sharma, S. Y. Wang, S. R. Shieh, L. C. Ming, S. W. Cheong

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4 Scopus citations


Raman and optical absorption studies under pressure have been conducted on KTb(MoO4)2 up to 35·5GPa. A phase transformation occurs at 2·7GPa 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 the α-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.

Original languageEnglish (US)
Pages (from-to)151-161
Number of pages11
JournalPramana - Journal of Physics
Issue number2
StatePublished - Aug 1996

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


  • Electronic transition
  • High pressure Raman spectroscopy
  • Optical spectroscopy
  • Phase transition
  • Potassium terbium molybdate


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