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Stability and Decomposition of Ca‐Substituted Lanthanum Ferrite in Reducing Atmospheres
Author(s) -
Price Patrick M.,
Butt Darryl P.
Publication year - 2015
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13569
Subject(s) - lanthanum , partial pressure , decomposition , thermal decomposition , oxygen , ferrite (magnet) , hydrogen , chemistry , lanthanum oxide , calcium , perovskite (structure) , inorganic chemistry , chemical decomposition , reducing atmosphere , materials science , analytical chemistry (journal) , oxide , metallurgy , crystallography , composite material , chromatography , organic chemistry
Calcium‐substituted lanthanum ferrites (La 1− x Ca x FeO 3−δ x = 0, 0.1, 0.2, 0.3, 0.4) were synthesized in air and subsequently decomposed in reducing atmospheres. The partial pressure of oxygen ( P O 2 ) was controlled by varying the H 2 /H 2 O ratio by bubbling hydrogen/argon mixtures through water baths at controlled temperatures. Three regions of mass loss were identified as the P O 2was reduced, two of which were determined to be associated with decomposition reactions. Calcium was shown to decrease the thermal stability of the perovskite compound, but rather than incrementally increasing the required P O 2for decomposition proportional to calcium concentration, all samples partially decomposed at a single P O 2 . The extent of the partial decomposition was dependent on the amount of calcium substitution and temperature. The perovskite phase remaining after the partial decomposition was found to fully decompose at the same oxygen partial pressure as pure lanthanum ferrite.