Pressure-Induced Phase Transitions in RbMnCl₃ Crystal—Raman Spectra and Lattice Dynamics

Abstract

Raman scattering spectra of RbMnCl ₃ crystal has been studied at ambient conditions and under high hydrostatic pressure. Results are interpreted within abinitio lattice dynamics approach. Experimental results agree rather well with numerical simulations at the lower frequencies range, while a bit worse—for higher frequency modes. The first transition was observed at 0.7 GPa in good agreement with earlier measurements, and spectral transformation agrees with transition to the perovskite cubic phase predicted theoretically. New transitions were found at 1.1 GPa and 5 GPa, presumably—to distorted cubic phases.

Keywords:

• RbMnCl₃
• pressure
• phase transitions
• Raman scattering
• lattice dynamics

Acknowledgment

The authors express their thanks to Prof. K. S. ALeksandrov for helpful discussion of this work and Dr. A. P. Shebanin for his assistance during high pressure measurements. The work has been performed under support of RFBR–Enisey grant # 02-02-97707.