Hydrostatic Pressure-Induced Phase Transitions in Rb₂KInF₆ and Rb₂KScF₆ Crystals: Raman Spectra and Lattice Dynamics Simulations

Abstract

Raman scattering spectra of Rb₂KInF₆ and Rb₂KScF₆ crystals have been studied under hydrostatic pressure up to 5.3 GPa at room temperature. Results are interpreted within semiempirical simulations of the lattice dynamics. Observed phase transitions both in Rb₂KInF₆ and Rb₂KScF₆ crystals are associated with condensation of soft F_1g phonon mode. High-pressure phases for both crystals are supposed to be of C2/m space group.

Keywords:

• Rb₂KInF₆
• Rb₂KScF₆
• phase transitions
• Raman scattering
• lattice dynamics

Acknowledgments

This work has been financially supported by grants: Russian Foundation for Basic Research (project nos. 11-02-98002-r_sibir’ and 09-02-00062), the Siberian Branch of the Russian Academy of Sciences (integration project no.101), and the Council on Grants from the President of the Russian Federation (grant no. HSh-4645.2010.2).