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

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

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
Volume47
Issue number2
DOIs
StatePublished - Aug 1996

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

Keywords

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

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