Structural characterization of electrical conductive vanadate glass

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 VVI(or VIII) to VV. Interestingly, a drastic increase of σ from 10-5 to 100 S cm-1 was observed when 20 BaO · 70 V2O5 · 10 Fe2O3 glass was isothermally annealed at around crystallization peak temperature (Tc) of 500°C, a quadrupole splitting(Δ) decreasing from 0.70 to 0.54 mm 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. (author)