Davemaoite, i.e., CaSiO3 perovskite (CaPv), is the third most abundant phase in the lower mantle and exhibits a tetragonal-cubic phase transition at high pressures and temperatures. The phase boundary in CaPv has recently been proposed to be close to the cold slab adiabatic and cause mid-mantle seismic wave speed anomalies (Thomson et al., Nature 572, 643, 2019). In this study, we utilized accurate deep-learning-based simulations and thermodynamic integration techniques to compute free energies at temperatures ranging from 300 to 3,000 K and pressures up to 130 GPa. Our results indicate that CaPv exhibits a single cubic phase throughout lower-mantle conditions. This suggests that the phase diagram proposed by Thomson et al. requires revision, and mid-mantle seismic anomalies are likely attributable to other mechanisms.
@article{arxiv.2401.14588,
title = {Deep-learning-based prediction of the tetragonal$\rightarrow$cubic transition in davemaoite},
author = {Fulun Wu and Yang Sun and Tianqi Wan and Shunqing Wu and Renata M. Wentzcovitch},
journal= {arXiv preprint arXiv:2401.14588},
year = {2024}
}