Pressure-induced changes in the optical properties of quasi-one-dimensional $\beta$-Na$_{0.33}$V$_2$O$_5$

TL;DR

This study investigates how high pressure affects the optical properties of $eta$-Na$_{0.33}$V$_2$O$_5$ crystals, revealing charge transfer and electron-phonon interactions through Raman and infrared spectroscopy.

Contribution

It provides new insights into pressure-induced charge transfer and electron-phonon coupling in $eta$-Na$_{0.33}$V$_2$O$_5$ using polarization-dependent spectroscopic techniques.

Findings

Charge transfer occurs between V sites at 9-12 GPa.

Electron-phonon coupling is significant at low pressures.

Optical properties are sensitive to pressure-induced structural changes.

Abstract

The pressure-induced changes in the optical properties of $\beta$-Na$_{0.33}$V$_2$O$_5$ single crystals at room temperature were studied by polarization-dependent Raman and far-infrared reflectivity measurements under high pressure. From the changes in the Raman- and infrared-active phonon modes in the pressure range 9 - 12 GPa a transfer of charge between the different V sites can be inferred. The importance of electron-phonon coupling in the low-pressure regime is discussed.