Structural features of the formation of La1−x Ca x FeO3−δ (0 ≤x ≤ 0.7) hetero valent solid solutions
| Autor: | A. N. Nadeev, Sergey V. Tsybulya, Lyubov A. Isupova, N. A. Kulikovskaya, E. Yu. Gerasimov |
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| Rok vydání: | 2010 |
| Předmět: |
Phase transition
Materials science Inorganic chemistry chemistry.chemical_element Partial pressure law.invention Inorganic Chemistry Crystallography chemistry law Phase (matter) Materials Chemistry Lanthanum Calcination Orthorhombic crystal system Physical and Theoretical Chemistry Solid solution Perovskite (structure) |
| Zdroj: | Journal of Structural Chemistry. 51:891-897 |
| ISSN: | 1573-8779 0022-4766 |
| DOI: | 10.1007/s10947-010-0135-7 |
| Popis: | A synthesis method with the use of polymer-salt compositions (calcination temperature 800°C) provides the preparation of various solid solutions of a La1−x Ca x FeO3−δ series in the 0≤ x≤ 0.7 range, which belong to the perovskite structure type. A morphotropic phase transition occurs from the orthorhombic perovskite modification (0≤ x ≤ 0.4) to the cubic one (0.5 ≤ x≤ 0.7). A growing number of microdistortions in the perovskite structure and the formation of a microblock structure in the morphotropic phase transition region are observed with increasing degree of calcium substitution for lanthanum. Calcination of solid solutions with x = 0.6 and 0.7 at temperatures above 1000°C in the air or under conditions of reduced oxygen partial pressure (laboratory vacuum of 10−3 Torr) results in the formation of a nanostructured state with coherently grown blocks of perovskite and Grenier phase, which is due to irreversible oxygen loss. |
| Databáze: | OpenAIRE |
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