Effect of two different dopants (Mg2+ and Ca2+) and processing parameters on γ-phase stabilization and conductivity of Bi4V2O11−δ

Mg2+ and Ca2+ doped Bi4V2O11−δ systems are synthesized by a melt quench technique followed by heat treatment. The Ca2+ doped samples show higher density than Mg2+ doped samples. All the quenched samples show γ-phase stabilization irrespective of dopants and their concentration. The γ-phase stabilization takes place at lower dopant concentration than earlier reported systems. The conversion of γ-phase to ordered β-phase is observed with heat treatment for Bi4V2−xMgxO11−δ (x=0.05, 0.10 and 0.20) and Bi4V2−xCaxO11−δ (x=0.05 and 0.10). Ca2+ doped system, particularly high concentration (x=0.15 and 0.20) did not show γ→γ׳ phase transition. The lowest activation energy; Ea is observed for Bi4Mg0.15V1.85O11−δ sample ~0.74 eV in the temperature range 570–750 °C.