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Stability and Properties of Brownmillerites Ca 2 (Al, Mn, Fe) 2 O 5 and Perovskites Ca(Mn, Fe)O 3− x in the System Ca 2 Fe 2 O 5 –“Ca 2 Mn 2 O 5 ”–“Ca 2 Al 2 O 5 ”
Author(s) -
Zötzl Matthias,
Pöllmann Herbert
Publication year - 2006
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/j.1551-2916.2006.01242.x
Subject(s) - manganese , materials science , mineralogy , crystallography , analytical chemistry (journal) , chemistry , metallurgy , chromatography
Solid solutions of manganese‐substituted brownmillerites and their stability range in the Ca 2 Fe 2 O 5 –“Ca 2 Mn 2 O 5 ”–“Ca 2 Al 2 O 5 ”‐system were investigated. Samples were synthesized by solid‐state reactions in temperature ranges at 1250°–1300°C. The phase development was investigated by powder X‐ray diffraction and d ‐spacings and lattice parameters of new phases were determined. Ternary solid solutions of the hydraulic brownmillerites crystallize in a wide range of compositions (C 2 F–C 6 A 2 F–C 6 A 2 Mn–C 4 AMn–C 6 A 0.5 F 2 Mn 0.5 –C 2 F 0.83 Mn 0.17 ). Brownmillerite, C 12 A 7 and C 3 A coexist at Al 3+ ‐additions above 66 mol%. Various oxygen defect perovskites are stable in the “C 4 FMn”–“C 2 Mn” field. “C 2 Mn” crystallizes as CaMnO 2.8 and “C 4 FMn” as CaFe 0.5 Mn 0.5 O 3− x . The other stability fields can be characterized by the coexistence of brownmillerite‐type solid solutions and by different oxygen defect perovskites depending on the amounts of manganese and reaction conditions.