Tysonite-type solid solutions in the BiF3-BiOF-BaF2 system: Polymorphism and anionic conductivity

V. A. Prituzhalov, E. I. Ardashnikova, V. A. Dolgikh, A. M. Abakumov

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Tysonite solid solutions Bi1-xBaxOyF 3-x-2y in the BiF3-BiOF-BaF2 system were obtained by solid-phase synthesis in sealed copper tubes in an argon atmosphere at 873 K with subsequent quenching. The solid solutions were studied by X-ray diffraction, electron diffraction, and impedance spectroscopy. On the basis of X-ray powder diffraction data, the homogeneity ranges of the tysonite solid solutions were deter-mined and the scheme of their location in the BiF 3-BiOF-BaF2 system at 873 K was suggested. Aliovalent substitutions in both the cation and anion sublattices Ba2+ →Bi3+ and O2- → F- made it possible to vary the concentration of anion vacancies. It was found that, at a high concentration of anion defects at 873 K, the hexagonal tysonite modification with space group P63/mmc is stable. With a decrease in the defect concen-tration, the trigonal tysonite modification with space group P3̄c1 becomes stable. An ordered monoclinic tysonite-type modification BiO yF3 - 2y (0.13 < y < 0.23) was revealed. For the homogeneity ranges of all tyso-nite phases, dependences of the unit cell parameters and conductivity on the composition along the sections with a constant barium or oxygen content were reported. The most probable location of oxygen anions and anion vacancies in the tysonite structure is discussed.

Original languageEnglish
Pages (from-to)313-324
Number of pages12
JournalRussian Journal of Inorganic Chemistry
Volume56
Issue number3
DOIs
Publication statusPublished - Mar 2011
Externally publishedYes

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