Thermal behaviour and polymorphism of BIMEVOX oxide ion conductors including the new materials: Bi4V2O11: M; M = La, Y, Mg, B

Abstract

The BIMEVOX materials can be prepared in four polymorphic modifications: α, β, γ, γ′, depending on Bi:V ratio and the nature/concentration of dopant. Polymorphic transitions take place on heat/cool cycles and can be detected by DTA and by variations in conductivity Arrhenius plots. A survey of thermal behaviour is given, using as examples several new BIMEVOX materials. Some conductivity values at 300°C are: Bi4V18Mg0.2O10.70, 1.1 × 103 Ω-1 cm-1; Bi4V1.8La0.2O10.8, 1.4 × 10-4 Ω1 cm-1; Bi4V1.8Y0.2O10.8, 1.0 × 10-4 Ω-1 cm-1; Bi4V1.8B0.2O10.8, 2.0 × 10-5 Ω1 cm-1.