Accurate identification of glass crystallization helps in selecting high electronic conductivity materials

Abstract

Though the current research on vanadium-based glass electrodes has made great progress, the conductivity theory of V-based glasses has not been obviously improved and crystals cannot be positioned precisely. The changes in the valence state of V³⁺, V⁴⁺ and V⁵⁺ are regulated by the strong reducing agent Fe₂P to realize valence bond transformation of the amorphous electrode, explore the redox process of multi-electron reactions and further optimize the conductivity of electrode materials. VPFe2 and VPFe3 precipitate VO₂ crystals and VPFe4 precipitates VO₂ and V₆O₁₁ crystals. Electron back-scattered diffraction was used to accurately identify the distribution and specific positions of both types of crystals. V₆O₁₁ crystals exhibit a strong texture according to pole figure and inverse pole figure. XPS reveals that Fe₂P and V₂O₅, undergo a redox reaction during the high-temperature melting process, where V⁵⁺ is reduced to V⁴⁺ and V³⁺ and V⁴⁺ renders a positive influence on conductivity. The addition of Fe₂P increases the content of V⁴⁺ in the glass and VPFe3 glass contains the highest content of V⁴⁺, leading to the highest electronic conductivity. V₂O₅ transforms into VO₂ crystals and VO₂ transforms into V₆O₁₁ with the increase of Fe₂P content. The type of nanocrystal precipitation in glass affects electronic conductivity.