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

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 (01) 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 pd pi bond between O-I and nearest V atom instigated by the formation of vanadyl O-I vacancy, confirmed from the downward shift of the bottom most split-off conduction bands in the material with increasing temperature.