Structures & Magnetic Ordering in the BrownMillerite Phases, Sr₂MnGaO₅ and Ca₂MnALO₅

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Abstract

The crystal and magnetic structures of the two related phases, Sr-2 MnGaO5 and Ca2MnAlO5 are reported. Rietveld analysis of neutron powder diffraction has revealed that both phases adopt the brownmillerite structure. Subtle differences in structure lead to the structure of Sr2 MnGaO5 being best described by the space group Icmm (a = 5.4888(2) Angstrom, b = 16.2256(6) Angstrom, c = 5.35450(2) Angstrom at 2 K) while that of Ca2MnAlO5 is best described by Ibm2 (a = 5.46258(9) Angstrom, b = 14.9532(3) Angstrom, c = 5.23135(8) Angstrom at 2 K). Low temperature neutron powder diffraction data show that both phases have a simple antiferromagnetic structure. However, magnetisation data suggest a more complex picture of the magnetic order within these phases.

Details

Original languageEnglish
Pages (from-to)978-982
Number of pages5
JournalJournal of Materials Chemistry
Volume12
Issue number4
Early online date5 Mar 2002
Publication statusPublished - 21 Mar 2002