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arXiv · 2505.01529

Ferroelasticity, shear modulus softening, and the tetragonal-cubic transition in davemaoite

Tianqi Wan·Chenxing Luo·Zhen Zhang·Yang Sun·Renata M. Wentzcovitch
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Abstract

Davemaoite (Dm), the cubic phase of CaSiO3-perovskite (CaPv), is a major component of the Earth's lower mantle. Understanding its elastic behavior, including its dissolution in bridgmanite (MgSiO3-perovskite), is crucial for interpreting lower mantle seismology. Using machine-learning interatomic potentials and molecular dynamics, we investigate CaPv's elastic properties across the tetragonal-cubic transition. Our equations of state align well with experimental data at 300 K and 2,000 K, demonstrating the predictive accuracy of our trained potential. We simulate the ferroelastic hysteresis loop in tetragonal CaPv, which has yet to be investigated experimentally. We also identify a significant temperature-induced shear modulus softening near the phase transition, characteristic of ferroelastic-paraelastic transitions. Unlike previous elasticity studies, our softening region does not extend to slab geotherm conditions. We suggest that ab initio-quality computations provide a robust benchmark for shear elastic softening associated with ferroelasticity, a challenging property to measure in these materials.

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Tianqi Wan, Chenxing Luo, Zhen Zhang, Yang Sun, Renata M. Wentzcovitch. 2025-05-02. Ferroelasticity, shear modulus softening, and the tetragonal-cubic transition in davemaoite. https://arxiv.org/abs/2505.01529

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