Structural Characterization of Electrical Conductive Vanadate Glass

Abstract

Vanadate glass is semiconductive with the electrical conductivity(σ) of 10⁻⁷ - 10⁻⁵ S cm⁻¹, which is caused by 3d electron(polaron) hopping from V^VI(or V^III) to V^V. Interestingly, a drastic increase of σ from 10⁻⁵ to 10⁰ S cm⁻¹ was observed when 20BaO·70V₂O₅·10Fe₂O₃ glass was isothermally annealed at around crystallization peak temperature(T_c) of 500°C, a quadrupole splitting(Δ) decreasing from 0.70 to 0.54mm s⁻¹. These results indicate that the increase in was in proportion to the decrease in the local distortion of FeO₄ tetrahedra as reflected in of the Mössbauer spectra. Based on the newly obtained results, the vanadate glass is expected to be a promising candidate as a cathode material of secondary battery. It is concluded that Mössbauer spectrometry is one of the essential techniques for the characterization of functional glasses and ceramics.