Bi- M/ M′- O ( M, M′ = alkaline-earth) and Bi- M/ M′- Pb- O: new members of the dimorphic rhombohedral Bi-Sr-O type anionic conductors family

• Published in: Solid state ionics 1996-07, Vol.86, p.289-295
• Main Authors: Drache, M., Wignacourt, J.P., Confiant, P.
• Format: Article
• Language: English
• Subjects: Anionic conductors; Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; Diffusion in solids; Exact sciences and technology; Phase transition; Physics; Rhombohedral polymorphism; Self-diffusion and ionic conduction in nonmetals; Structure of solids and liquids; crystallography; Transport properties of condensed matter (nonelectronic)
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/0167-2738(96)00126-9

Significant domains of the dimorphic Bi-Sr-O rhombohedral type phases have been evidenced in Bi-M/M'-O and Bi- M/ M′- Pb- O materials ( M, M′ = Ca, Sr, Ba). Their stability, their structural and electrical conductivity properties have been investigated. Sr or Ba for Ca substitution in Bi 0.75Ca 0.125Pb 0.125O 1.374 allows the preservation of the β 1 high temperature form, by air quenching, within the limits 0.2 ≤ Sr (Sr + Ca) ≤ 0.8 and 0.1 Ba (Ba + Ca) ≤ 0.6 . In absence of lead, the occurrence of β 2 or β 1 domain has been investigated, in particular Bi-Sr Ba-O samples. It is possible to quench β 1 for bismuth rich compositions, but the extent of the corresponding domain is related to the quenching conditions: Bi 0.844Sr 0.156(1 − x)Ba 0.156 x O 1.422 samples adopt the stable low temperature β 2 type. Their thermal behaviour investigation has pointed out the occurrence of a cationic order, which is confirmed by a single crystal X-ray diffraction study.