The Anionic Superconductor Bi3BaO5.5: A bcc Structure Closely Related to the Perovskite. Relationships with Anti α-AgI
✍ Scribed by C. Michel; D. Pelloquin; M. Hervieu; B. Raveau; F. Abbattista; M. Vallino
- Book ID
- 102605495
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 231 KB
- Volume
- 109
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The average bcc structure of (\mathrm{Bi}{3} \mathrm{BaO}{5.5}(a=4.3822(2) \AA)) has been determined by powder neutron diffraction. The calculations performed in the space group (I m 3 m) have slown that the (B i) and Ba atoms are statistically distributed over the (2(a)) sites ((0,0,0)), whereas oxygen and anionic vacancies are statistically distributed over the (6(b)) sites ((1,0,0)). The cationic positions and the large anisotropic thermal factors of the oxygen atoms resemble the anti (\alpha)-Agl structure. However, the anionic positions correspond to those observed in the perovskite. Thus, contrary to (\mathrm{Cd}{0.79} \mathrm{Cd}{0.21} \mathrm{O}{1.39}), this phase cannot be considered as an anti (\alpha) (\mathrm{AgI}) structure. It can better be described as the coexistence of the two configurations of the perovskite inside the crystals. Ionic conductivity measurements show that this phase is an anionic conductor with an activation energy of (0.90 \mathrm{eV}) and (T{673 \mathrm{~K}} \approx 10^{-3}) (\mathbf{\Omega}^{-1} \mathrm{~cm}^{-1}). 1994 Academic Press, fnc.