An oxygen deficient fluorite with a tunnel structure: Bi sub 8 La sub 10 O sub 27

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Journal of Solid State Chemistry; (USA)

DOI:https://doi.org/10.1016/0022-4596(91)90146-9· OSTI ID:5491832

Michel, C; Caignaert, V; Raveau, B ^[1]

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1. ISMRA, Caen (France)

A new lanthanum bismuth oxide, Bi{sub 8}La{sub 10}O{sub 27}, has been synthesized. It crystallizes in the Immm space group with the following parameters: a = 12.079 (2) {angstrom}, b = 16.348 (4) {angstrom}, c = 4.0988 (5) {angstrom}. Its structure was determined from powder X-ray and neutron diffraction data. It can be described as an oxygen deficient fluorite superstructure (a {approx} 3a{sub F}/{radical}2, b {approx} 3a{sub F}, c {approx} a{sub F}/{radical}2) in which bismuth and lanthanum, as well as oxygen vacancies, are ordered. The structure consists of fully occupied (110) or ({bar 1}10) lanthanum planes (La) which alternate with mixed {l brace}{sub La}{sup Ba}{r brace} planes and fully occupied oxygen planes (A) which alternate with two sorts of oxygen deficient (110) or ({bar 1}10) planes (B and C) according to the sequence -{l brace} La A B {l brace}{sub La}{sup Bi}{r brace} C C {l brace}{sub La}{sup Bi}{r brace} B A {l brace}-. The anionic distribution determines tunnels where the bismuth ions are located, forming diamond-shaped based tunnels. The coordination of bismuth and lanthanum is discussed. The high thermal factor of some oxygen atoms suggests that this oxide exhibits ionic conductivity.

• OSTI ID: 5491832
• Journal Information: Journal of Solid State Chemistry; (USA), Journal Name: Journal of Solid State Chemistry; (USA) Vol. 90:2; ISSN 0022-4596; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
BISMUTH COMPOUNDS
BISMUTH OXIDES
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
DATA
DATA ANALYSIS
DIFFRACTION
EXPERIMENTAL DATA
INFORMATION
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LATTICE PARAMETERS
NEUTRON DIFFRACTION
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
SCATTERING
SPACE GROUPS
X-RAY DIFFRACTION