HR: 1340h
AN: MR23A-0186    [Abstracts]
TI: Phase Relation and Structural Variation on the Join CaIrO$_{3}$-CaTiO$_{3}$
AU: * Fujita, Y
EM: yfujita@geo.titech.ac.jp
AF: Tokyo Institute of Technology, 2-12-1,Ookayama, Tokyo, 152-8551 Japan
AU: Hirose, K
EM: kei@geo.titech.ac.jp
AF: Tokyo Institute of Technology, 2-12-1,Ookayama, Tokyo, 152-8551 Japan
AU: Tateno, S
EM: stateno@geo.titech.ac.jp
AF: Tokyo Institute of Technology, 2-12-1,Ookayama, Tokyo, 152-8551 Japan
AB: CaTiO$_{3}$ is found in nature as perovskite and is isostructural with a major lower mantle mineral of MgSiO$_{3}$ perovskite (space group {\it Pbnm}). Recent high-pressure experiments demonstrated that MgSiO$_{3}$ perovskite undergoes first-order structural phase transition to a post-perovskite phase above 125 GPa and 2500 K. CaIrO$_{3}$ has an orthorhombic symmetry with space group {\it Cmcm} that is the same structure as that of MgSiO$_{3}$ post-perovskite phase. The structural variation on the join CaTiO$_{3}$-CaIrO$_{3}$ is, therefore, of interest as analogy to the pressure-induced phase transition from perovskite to post-perovskite phase in MgSiO$_{3}$. We examined phase equilibria on the join CaTiO$_{3}$-CaIrO$_{3}$ at 1 GPa and 1400 _E#8249;C using a piston-cylinder apparatus. Three starting materials with Ti/Ir molar ratios of 0.25, 1, and 4 were preliminarily prepared as powder mixtures of CaTiO$_{3}$ and CaIrO$_{3}$ crystals. CaIrO$_{3}$ were synthesized from CaCO$_{3}$ and IrO2 in the air at 1000 _E#8249;C. Results show that a wide range of compositions from pure CaTiO$_{3}$ at least to Ca(Ir$_{0.78}$Ti$_{0.22}$)O$_{3}$ form continuous solid solution with perovskite structure. Phase relations in more Ir-rich composition and the structural variations both of perovskite and CaIrO$_{3}$-type structures will be discussed in detail.
DE: 7207 Core and mantle
DE: 3630 Experimental mineralogy and petrology
DE: 3924 High-pressure behavior
DE: 1212 Earth's interior--composition and state (8105)
DE: 1213 Earth's interior--dynamics (8115, 8120)
SC: Mineral and Rock Physics [MR]
MN: 2004 AGU Fall Meeting