High-pressure phase transition of α-NaVO3 by Raman spectroscopy

Abstract

In an earlier study, we showed that α-NaVO3 undergoes a crystalline-amorphous phase transition at approx.60 kbar. Below the amorphization pressure, some spectral changes were observed in the Raman spectra, but due to the polycrystalline nature of the samples used in these experiments, these changes were not clearly demonstrated. Here we report on high-pressure studies of α-NaVO3 using single-crystal samples in the pressure range below 60 kbar. A first-order crystalline-crystalline phase transition occurred at 43 kbar. The transition was marked by the appearance of new Raman bands in both the internal and external vibrational regions, and the single-crystal sample shattered after the transition. Continuous spectral changes were observed for the Raman bands associated with the rocking, wagging and twisting motions preceding the transition.