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Title: The anionic superconductor Bi[sub 3]BaO[sub 5. 5]: A bcc structure closely related to the perovskite. Relationships with anti [alpha]-AgI

Journal Article · · Journal of Solid State Chemistry; (United States)
; ; ;  [1]; ;  [2]
  1. Universite da Caen (France)
  2. Politecnico di Torino, Turin (Italy)

The average bcc structure of Bi[sub 3]BaO[sub 5.5] (a = 4.3822(2) [angstrom]) has been determined by powder neutron diffraction. The calculations performed in the space group Im3m have shown that the Bi 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 (1/2,0,0). The cationic positions and the large anisotropic thermal factors of the oxygen atoms resemble the anti [alpha]-AgI structure. However, the anionic positions correspond to those observed in the perovskite. Thus, contrary to Cd[sub 0.79]Cd[sub 0.21]O[sub 1.39], this phase cannot be considered as an anti [alpha]-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 eV and T[sub 673 K] [approximately] 10[sup [minus]3] [Omega][sup [minus]1] cm[sup [minus]1].

OSTI ID:
6661330
Journal Information:
Journal of Solid State Chemistry; (United States), Vol. 109:1; ISSN 0022-4596
Country of Publication:
United States
Language:
English