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Phase relations in Mg 3 Al 2 Si 3 O 12 to 180 GPa: Effect of Al on post‐perovskite phase transition
Author(s) -
Tateno Shigehiko,
Hirose Kei,
Sata Nagayoshi,
Ohishi Yasuo
Publication year - 2005
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 - 10.1029/2005gl023309
Subject(s) - perovskite (structure) , post perovskite , phase (matter) , materials science , pyrope , diamond anvil cell , mineralogy , diffraction , crystallography , phase transition , analytical chemistry (journal) , geology , high pressure , thermodynamics , chemistry , transition zone , optics , physics , geochemistry , organic chemistry , chromatography
Phase relations in Mg 3 Al 2 Si 3 O 12 (MgSiO 3 + 25 mol% Al 2 O 3 ; pyrope garnet composition) were investigated on the basis of in‐situ synchrotron X‐ray diffraction measurements at high‐pressure and ‐temperature in a laser‐heated diamond anvil cell (LHDAC). Results demonstrate that perovskite is solely stable up to 140 GPa and 2200 K, and perovskite and CaIrO 3 ‐type post‐perovskite phase (space group: Cmcm ) coexist above 140 GPa and 2200 K. Post‐perovskite is formed as a single phase above 150–170 GPa. Previous study has shown that pure MgSiO 3 perovskite transforms to post‐perovskite phase above 125 GPa and 2500 K based on the same pressure standard. These results indicate that addition of Al 2 O 3 expands the stability of MgSiO 3 perovskite relative to post‐perovskite.