AURIVILLIUS PHASES (Bi2O2)(An-1BnO3n+1) (n = 1 - 8)

Bi2WO6 single crystals
 

Numerous Aurivillius phases are layered perovskite like compounds with constant (ordinary phases) or alternating (mixed layer phases, intergrowths) number of "perovskite" layers (n = 1 - 8) between layers of Bi2O2.

Ferroelectric and oxide-ion conductive properties of single-layer phases, such as Bi2WO6, Bi2MoO6, Bi2VO5.5, and intergrowths Bi6Ti3WO18 and Bi10Ti3W3O30 were investigated. At first time it was found that Bi2WO6 exhibit high ionic conductivity caused by fast migration of oxygen anions. The complex polymorphism of Bi2WO6 and Bi2MoO6 was refined (see a scheme below).

Solid solutions in Bi2WO6 - Bi2VO5.5, Bi2MoO6 - Bi2VO5.5 and Bi2GeO5 - Bi2VO5.5 were investigated with aim to make better oxide conductive properties. Phase transition peculiarities in the above compounds have been also studied.

Special attention was given to study of polymorphism and properties of mixed layer compound Bi10Ti3W3O30 with high anionic conductivity (~10-2 Ohm-1cm-1 at 800oC).

The general question of symmetry and its changes at ferroelectric phase transitions have been analyzed for the first time.

Conductivity temperature dependences for different Aurivillius phases

 

Schemes of the phase transitions for (1) Bi2MoO6 and (2) Bi2WO6 with summary concerning phase structures:
(a) – the structure has been solved experimentally and space group is well-known (F. Theobald et al.,1984; D.J. Buttrey et al.,1994; R.W. Wolfe et al., 1969, N.A. McDowell et al., 2006; and many other authors 1965 - present time);
(b) – the structure has not been solved experimentally, space group have been predicted in theory (A.D. Rae, 1991);
(c) – the structure has not been solved, point group have been proposed based on properties of the compounds.

 
Main publications:
  1. V.K.Yanovskii, V.I.Voronkova, A.L.Aleksandrovskii, and V.A.D'yakov. Structure and properties of ferroelectric Bi2WO6 crystals. // Doklady AN SSSR, 1975, v.222, p.94.
  2. V.I.Voronkova and V.K.Yanovskii. Growth of Bi2WO6 single crystals. // Kristallografiya, 1977, v.22, p. 429.
  3. V.I.Utkin, Yu.E.Roginskaya, V.I.Voronkova, V.K.Yanovskii, B.Sh.Galyamov, and Yu.N.Venevtsev. Dielectric properties, electrical conductivity and relaxation phenomena in ferroelectric Bi2WO6. // Phys. Stat. Solidi (a) , 1980, v.59, p. 75.
  4. V.K.Yanovskii, V.I.Voronkova, Yu.E.Roginskaya, and Yu.N.Venevtsev. Fast anionic transport in the Bi2WO6 crystals. Fiz. tverdogo tela, 1982, v.24, p.2829.
  5. V.K.Yanovskii and V.I.Voronkova. Polymorphism and properties of Bi2WO6 and Bi2MoO6. Phys. stat. sol. (a) , 1986, v.93, p.57.
  6. V.K.Yanovskii and V.I.Voronkova. The structure and ferroelectric properties of layered compounds in the system Bi2WO6 - Bi4Ti3O12. Phys. stat. sol. (a) , 1987, v.101, p.45.
  7. V.K.Yanovskii and V.I.Voronkova. Structure, polymorphism and ferroelectric properties of mixed-layered bismuth containing compounds. Neorg. Mater., 1986, v.22, p. 2029.
  8. V.K.Yanovskii and V.I.Voronkova. Ferroelectric bismuth-containing compounds with the mixed-layered perovskite-like structure. Kristallografiya, 1988, v.23, p. 1278.
  9. V.K.Yanovskii, V.I.Voronkova, and I.N.Leont'eva. Structure and electrophysical properties of the mixed layered phases in the system Bi5Nb3O15 - Bi5Ti1.5W1.5O15. Neorg. Mater., 1989, v.25, p.834.
  10. V. I. Voronkova, V. K. Yanovskii, E. P. Kharitonova, O.G. Rudnitskaya. Superionic conductors in the Bi2WO6 – Bi2VO5.5 system // Inorganic Materials. 2005. V.41. No.7. p. 760 - 765.
  11. E. P. Kharitonova, V. I. Voronkova, V. K. Yanovskii. Electrical conductivity of Bi2WO6 crystals doped with Ca2+, Pb2+, Sr2+, and Ba2+ // Inorganic Materials. 2005. V.41. No.7. p. 757 - 759.
  12. E.P. Kharitonova, V.I. Voronkova. Synthesis and electrical properties of Bi2V1-xGexO5+y solid solutions. // Inorganic Materials. 2007. V.43. No.1. p. 60 - 65.
  13. V. I. Voronkova, E. P. Kharitonova, O. G. Rudnitskaya, N.I. Sorokina, I.A. Verin. Synthesis and electrical properties of Aurivillius phases in the Bi2MoO6-Bi2VO5.5 system. // Crystallography Reports. 2007. V. 52. No. 2. p. 316-319.
  14. E.P. Kharitonova, V.I. Voronkova. Synthesis and Electrical Properties of Mixed-Layer Aurivillius Phases. // Inorganic Materials. 2007. V. 43. No. 12. p. 1488-1493.
  15. V.I. Voronkova, E.P. Kharitonova, O.G. Rudnitskaya. Refinement of Bi2WO6 and Bi2MoO6 polymorphism // Journal of Alloys and Compounds. 2009. in press.

 

 

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