Role of Vanadyl Oxygen in Understanding Metallic Behavior of V2O5(001) Nanorods

TL;DR

This study investigates how vanadyl oxygen vacancies influence the metallic transition in V2O5 nanorods, revealing the atomic-level mechanisms behind its temperature-induced semiconductor to metal change.

Contribution

It demonstrates the specific role of vanadyl oxygen in the metallic behavior of V2O5 nanorods through temperature-dependent Raman spectroscopy and electronic structure analysis.

Findings

Vanadyl oxygen vacancies are key to metallic transition.

Breakdown of pdpi bonds causes conduction band shifts.

V2O5 nanorods exhibit temperature-dependent structural changes.

Abstract

Vanadium pentoxide (V2O5), the most stable member of vanadium oxide family, exhibits interesting semiconductor to metal transition in the temperature range of 530-560 K. The metallic behavior originates because of the reduction of V2O5 through oxygen vacancies. In the present report, V2O5 nanorods in the orthorhombic phase with crystal orientation of (001) are grown using vapor transport process. Among three nonequivalent oxygen atoms in a VO5 pyramidal formula unit in V2O5 structure, the role of terminal vanadyl oxygen (OI) in the formation of metallic phase above the transition temperature is established from the temperature-dependent Raman spectroscopic studies. The origin of the metallic behavior of V2O5 is also understood due to the breakdown of pdpi bond between OI and nearest V atom instigated by the formation of vanadyl OI vacancy, confirmed from the downward shift of the bottom most split-off conduction bands in the material with increasing temperature.