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Electronic structure and magnetic properties of Al‐doped Ca 2 Fe 2 O 5 brownmillerite compounds
Author(s) -
Phan TheLong,
Tran Ngo,
Kim Deok Hyeon,
Tho Pham T.,
Huy Bui T.,
Dang Toan N.,
Yang DongSeok,
Lee Bowha
Publication year - 2018
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.15357
Subject(s) - brownmillerite , coercivity , orthorhombic crystal system , materials science , magnetization , analytical chemistry (journal) , crystallography , ferromagnetism , raman spectroscopy , crystallite , x ray crystallography , crystal structure , diffraction , chemistry , perovskite (structure) , condensed matter physics , physics , chromatography , quantum mechanics , magnetic field , optics
Polycrystalline Ca 2 Fe 2− x Al x O 5 ( x = 0‐1.4) samples were prepared by conventional solid‐state reactions. Their crystalline/electronic structures and magnetic properties were characterized in detail. Powder X‐ray diffraction analyses revealed that the samples crystallized in orthorhombic brownmillerite‐type structures with the occurrence of the Pcmn ‐ Ibm 2 phase separation in the region between x = 0.4 and 0.6. The results obtained from analyzing Raman scattering and X‐ray‐absorption fine‐structure spectra also indicated this phase separation. Although x in Ca 2 Fe 2− x Al x O 5 varies in a wide range from 0 to 1.4, the +3 oxidation state of Fe remained almost unchanged. Magnetization measurements revealed that all Ca 2 Fe 2− x Al x O 5 samples have weak ferromagnetic order, and both the saturation magnetization and coercive force are dependent on the temperature, x , and structure phases.
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