Raman Scattering Study Temperature Phase Transitions of Rb₂KInF₆ Crystal

Abstract

Raman scattering spectra of Rb₂KInF₆ crystal have been studied in a wide temperature range, including two phase transitions: from cubic to tetragonal, and then – to the monoclinic phase. Hardening of soft phonon modes was observed that attributes them to the transitions of displacive type. Parameters of Raman lines have been quantitatively analyzed and found in good agreement with known thermodynamic characteristics of these transitions. No evidences of order – disorder processes were observed in the Raman spectra of the high-symmetry phase.

Keywords:

• Rb₂KInF₆
• temperature phase transitions
• Raman scattering
• lattice dynamics

PACS number:

• 78.30.Hv
• 78.30.-j

Acknowledgment

Authors wish to thank prof. K. S. Aleksandrov and prof. I. N. Flerov for their valuable support and useful discussions. This work has been financially supported by grants RFFBR 08-02-00066, 09-02-00062, SS-1011.2008.2.