Phase transition in CaSiO3 perovskite

T. Komabayashi, K. Hirose, L.S. Dubrovinsky, N. Sata, Y. Ohishi

Research output: Contribution to journalArticlepeer-review

Abstract

A phase transition in pure CaSiO3 perovskite was investigated at 27 to 72 GPa and 300 to 819 K by in-situ X-ray diffraction experiments in an externally-heated diamond-anvil cell. The results show that CaSiO3 perovskite takes a tetragonal form at 300 K and undergoes phase transition to a cubic structure above 490-580 K in a pressure range studied here. The transition boundary is strongly temperature-dependent with a slightly positive dT / dP slope of 1.1 (± 1.3) K/GPa. It is known that the transition temperature depends on AlO content dissolved in CaSiO3 perovskite [Kurashina et al., Phys. Earth Planet. Inter. 145 (2004) 67-74]. The phase transition in CaSiO3(+ 3 wt.% AlO) perovskite therefore could occur in a cold subducted mid-oceanic ridge basalt (MORB) crust at about 1200 K in the upper- to mid-lower mantle. This phase transition is possibly ferroelastic-type and may cause large seismic anomalies in a wide depth range.
Original languageEnglish
Pages (from-to)564-569
Number of pages6
JournalEarth and Planetary Science Letters
Volume260
Issue number3-4
DOIs
Publication statusPublished - 30 Aug 2007

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