Work

First Observation of Quenched Davemaoite to Ambient Conditions: Its Electron Diffraction Pattern

Year: 2025

Type: article

Abstract: Calcium‐rich silicate perovskite (davemaoite) has been for the first time investigated at ambient pressure by electron diffraction in transmission electron microscopy. The obtained diffraction pattern in comparison to that of the coexisting Mg‐rich silicate perovskite (bridgmanite) has revealed the cubic symmetry, Pm m , the lattice parameter a = 0.3561(4) nm and the volume V 0 = 45.16(10) Å 3 (27.19 cm 3 /mol), which is still larger molar volume than that of the coexisting bridgmanite (25.49 cm 3 /mol). With large volume difference davemaoite and bridgmanite coexist at equilibrium under the conditions at 40 GPa and 2,000°C. The nanometer‐sized crystalline davemaoite (4.27 g/cm 3 ) is mantled by the amorphous CaSiO 3 (2.82 g/cm 3 ). This core‐mantle structure prevents amorphization of the unstable high‐pressure mineral at the core due to a static pressure, 1.2(10) GPa generated by volume expansion on the transition at the mantle. This mechanism is the same as that of high‐pressure minerals preserved in shocked meteorites.

Source: Geophysical Research Letters

DOI: 10.1029/2025gl115280

Authors: Nobuyoshi Miyajima, Lin Wang, Tomoo Katsura

Institutions: University of Bayreuth, Chinese Academy of Sciences, Institute of Geochemistry

Language: English

Topic: High-pressure geophysics and materials

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,190

Funder: Deutsche Forschungsgemeinschaft