Observation of an intermediate phase in the K3Na(CrO4)2 ferroelastic by Raman scattering

This paper reports on the first study in K3Na(CrO4)2 crystals of Raman spectra within a broad temperature interval of 4–300 K. The study has revealed significant variations in the intensity and shape of the Raman lines at T = 150 K; a group theory analysis has revealed that the structural phase transition in this ferroelastic proceeds in two stages through an intermediate phase: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P\bar 3m1 \to C2/m \to C2/c$$\end{document}.