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High‐pressure phase transition in Mn 2 O 3 : Application for the crystal structure and preferred orientation of the CaIrO 3 type
Author(s) -
Santillán Javier,
Shim SangHeon,
Shen Guoyin,
Prakapenka Vitali B.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026423
Subject(s) - annealing (glass) , materials science , phase transition , differential stress , crystallography , perpendicular , diffraction , condensed matter physics , differential thermal analysis , deformation (meteorology) , chemistry , optics , geometry , composite material , physics , mathematics
Our X‐ray diffraction measurements reveal that Mn 2 O 3 undergoes a phase transition to the CaIrO 3 type, which is proposed for the post‐perovskite in MgSiO 3 , at 27–38 GPa and 300 K, bypassing the other phase transitions observed in sesquioxides. Small distortions in the polyhedra after the transition indicate that the Jahn‐Teller effect, which is strong at ambient conditions, is suppressed during the transition. The CaIrO 3 ‐type phase exhibits strong preferred orientation of the (010) plane perpendicular to the loading axis before annealing whereas preferred orientation of the (100) and (110) planes was observed after annealing. The pre‐annealing texture may result from either the deformation under strong differential stresses or the phase transition. The post‐annealing texture may be related to either lower differential stresses or thermal annealing. Our result shows that the texture of the CaIrO 3 type can be sensitive to phase transition and annealing as well as differential stresses.