STOICHIOMETRY AND STABILITY OF BISMUTH VANADATE, BI4V2O11, SOLID-SOLUTIONS

The phase reported in the literature as Bi4V2O11 is a solid solution phase whose composition covers the range approximately 66.7 to 70.4% Bi2O3. The phase diagram of the Bi2O3-V2O5 system in the region of this phase has been determined and electrical properties of the Bi4V2O11 solid solutions measured. The high temperature gamma polymorph is an excellent oxide ion conductor, whose conductivity decreases gradually with increasing Bi2O3 content. The low temperature alpha polymorph is a ferroelectric whose permittivity appears to increase to a maximum at the alpha --> beta transition temperature.