Mössbauer Study of Water-Resistive Conductive Vanadate Glass

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Glass transition temperature(T_g) of 20BaO·10Fe₂O₃·xWO₃·(70−x)V₂O₅ glasses showed a step-by-step increase from 339 to 470°C when x was increased from 0 to 50, together with a concordant increase in crystallization temperature(T_c) from 406 to 531°C. Plot of T_g against quadrupole splitting(Δ) of Fe^III in the Mössbauer spectra yielded a straight line with a slope of 680K(mm s⁻¹)⁻¹. This indicates that Fe^III atoms constitute distorted FeO₄ tetrahedra and play a role of network former in the 3D-glass network. Dissolution of vanadium ions from vanadate glass into boiling water was suppressed from 34 to 2mg L⁻¹ when x was modified from 0 to 50, reflecting that introduction of WO₃ into the 3D-network of vanadate glass is effective in the improvement of water resistivity. A gradual decrease of Δ was observed from 0.82 to 0.76mm s⁻¹ after isothermal annealing of vanadate glass(x＝20) at 500°C for 240min, indicating structural relaxation of the glass network, and a marked increase in conductivity (σ) from 3.9×10⁻⁶ to 2.1×10⁻³ S cm⁻¹ was observed at room temperature.