Spectroscopic evidence of pressure-induced amorphization in α-NaVO3

Raman spectra of α-${\mathrm{NaVO}}_3$ were recorded under pressures up to 170 kbar at room temperature. A crystalline-amorphous phase transition was found at ∼61 kbar, much lower than the pressures of other ionic materials. This transition is marked by the sudden appearance of very broad bands at the 800- and 350-${\mathrm{cm}}^{\mathrm{-}1}$ regions. The amorphization involves the complete breaking up of the infinite chains of corner-linked tetrahedral ${\mathrm{VO}}_4$, most likely into ${\mathrm{VO}}_3^{\mathrm{-}}$. On decompression, the amorphous phase transforms to another phase, probably also amorphous at ∼40 kbar. It reverts to the stable ambient-condition α phase upon heating.