Lattice dynamics and high‐pressure properties of K‐ionic conducting system KNbTeO₆

Abstract

In the present work, we report results of high-pressure Raman scattering spectroscopy, on the ionic conducting system KNbTeO 6 , as well as lattice dynamics calculations for this compound. From lattice dynamics calculation, we were able to do a definite assignment of modes for this system taking into account the disorder caused by random K occupation and shared occupation of Nb and Te ions. On the basis of the theoretical results, we discuss the changes observed in the high-pressure Raman spectra. We report a transformation occurring around 4.7 GPa, attributed it to a structural phase transition. The Raman spectra during the decompression process reveals that all changes undergone by the structure are reversible, and the Raman spectrum recovers its original signature.