High pressure dissociation of CaTiO$_3$ perovskite into CaO and CaTi$_2$O$_5$ - Archive ouverte HAL Access content directly
Journal Articles Physics of the Earth and Planetary Interiors Year : 2022

High pressure dissociation of CaTiO$_3$ perovskite into CaO and CaTi$_2$O$_5$

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Abstract

In this study, we investigated phase transformations of CaTiO$_3$ perovskite using X-ray diffraction at high pressure and high temperature up to 170 GPa and 4500 K in a laser-heated diamond-anvil cell. We report a high-pressure dissociation of CaTiO$_3$ into CaO-B2 and CaTi2O5 with a monoclinic P2/m structure, instead of the expected transformation of the orthorhombic distorted perovskite structure into a post-perovskite phase. We propose that this transition may be favored by the B1 to B2 phase change of CaO at around 60 GPa. In order to provide additional information on the high pressure properties of CaTiO$_3$ perovskite, we measured its melting temperature using CO$_2$ laser heated diamond anvil cell up to 55 GPa yielding a fit of the melting curve to a Kraut-Kennedy empirical law according to: Tm (K) = 2188 ∗ [1 + 4.23 ∗ (ΔV/V0)]. To provide some further insight into the thermodynamic properties of CaTiO$_3$, we determined the P-V-T equation of state of the orthorhombic mineral perovskite, fitted by using a third order Birch-Murnaghan equation of state and a Berman thermal expansion model. The fit of the data yields to K0 = 180.6(4) GPa, K′0 = 4 (fixed), ∂K/∂T = −0.022(1) GPa K−1, α1 = 3.25(5) x 10−5 K−1, α2 = 1.3(1) x 10−8 K−2
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Dates and versions

hal-03852265 , version 1 (14-11-2022)

Identifiers

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B Truffet, G Fiquet, G Morard, M A Baron, F Miozzi, et al.. High pressure dissociation of CaTiO$_3$ perovskite into CaO and CaTi$_2$O$_5$. Physics of the Earth and Planetary Interiors, 2022, 2022, pp.106968. ⟨10.1016/j.pepi.2022.106968⟩. ⟨hal-03852265⟩
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