Bi0.85Ln0.15(1-n)V0.15nO1.5+0.15n Fluorite Type Oxide Conductors: Stability, Conductivity, and Powder Crystal Structure Investigations

To extend the study of Bi3O3–Ln2O3–V2O5 systems, an investigation of Bi0.85Ln0.15(1-n)V0.15nO1.5+0.15n materials (Ln=La, Pr, Nd, Sm, Tb, Ho, Yb), which adopt a fluorite-related structure for specific composition ranges, has been realized. The composition dependence of thermal stability of the structure evidenced using thermodiffractometry, and of conductivity properties determined from impedance spectroscopy, has been investigated. The pure anionic oxide conductor behavior evidenced by emf measurements of an oxygen concentration cell for Bi0.85Pr0.105V0.045O1.545 mixed oxide can be considered for other samples containing other rare earths. X-ray powder crystal structure refinements have been realized for praseodymium-containing terms Bi0.85Pr0.15(1-n)V0.15nO1.5+0.15n; n=0.1, 0.3, 0.5) and for a selection of the other lanthanide elements (Ln=La, Sm, Tb, Ho, and Yb) with n=0.3, on the basis of the Willis model. The stability and modification of the crystal structure are discussed.