Oxidative nonstoichiometry in perovskites, an experimental survey; the defect structure of an oxidized lanthanum manganite by powder neutron diffraction
Oxide perovskites showing oxidative nonstoichiometry (ABO 3+ x ) have been investigated. The structure of LaMn 3+ 0.76Mn 4+ 0.24O 3.12 has been investigated by powder neutron diffraction and a composition (La 0.94±0.02□ 0.06±0.02)(Mn 3+ 0.745Mn 4+ 0.235□ 0.02)O 3 with partial elimination of La 2O 3...
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Published in | Journal of solid state chemistry Vol. 10; no. 3; pp. 183 - 194 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Elsevier Inc
01.01.1974
|
Online Access | Get full text |
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Summary: | Oxide perovskites showing oxidative nonstoichiometry (ABO
3+
x
) have been investigated. The structure of LaMn
3+
0.76Mn
4+
0.24O
3.12 has been investigated by powder neutron diffraction and a composition (La
0.94±0.02□
0.06±0.02)(Mn
3+
0.745Mn
4+
0.235□
0.02)O
3 with partial elimination of La
2O
3 and vacancies on both the A and B metal sites determined. A much smaller degree of nonstoichiometry has been found for LaVO
3+
x
(
x ⩽ 0.05), and LaCrO
3, and EuTiO
3 did not show nonstoichiometry under the conditions used. A single phase region from Ba
0.8La
0.2Ti
4+
0.8Ti
3+
0.2O
3.0 to Ba
0.8La
0.2Ti
4+O
3.1 has been confirmed for lanthanum-doped BaTiO
3, but the solubility of La
3+ in SrTiO
3 is very small; consideration of the ionic radii indicates that the dopant ion of higher oxidation state must be significantly smaller than the normal ion to stabilize a wide nonstoichiometric region with B site vacancies. The extensive nonstoichiometry shown by LaMnO
3+
x
, in contrast to the other lanthanum-transition-metal perovskites LaBO
3, may result from the much larger reduction in ionic radius from Mn
3+ to Mn
4+ than is found for other transition-metal ions. |
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ISSN: | 0022-4596 1095-726X |
DOI: | 10.1016/0022-4596(74)90025-5 |