Year: 2025
Type: article
Abstract: Understanding the mineralogy of exoplanets is essential for unraveling their interior structures, dynamics, and evolution. For large super‐Earths, the post‐post spinel , one of the major mantle phases, may undergo the order‐disorder transition (ODT) at high temperatures. However, the ODT phase boundary of has not been rigorously constrained. Additionally, fundamental thermodynamic properties of the disordered remain poorly investigated. Here, we develop a unified machine learning potential (MLP) for of ab initio accuracy under super‐Earth mantle conditions. With the efficient MLP, we extensively calculate the free energy of post‐post spinel via the thermodynamic integration method. The results are used to constrain the ODT phase boundary. Furthermore, we report the P‐V‐T equation of state and Grüneisen parameters for post‐post spinel across various degrees of disorder. These thermodynamic properties are further applied to update the adiabatic thermal profiles and the mass‐radius relation of super‐Earths.
Source: Geophysical Research Letters
DOI: 10.1029/2025gl118419
Authors: Donghao Zheng, Yifan Li, Yihang Peng, Rushi Gong, Zi‐Kui Liu, Jie Deng
Institutions: Princeton University, Pennsylvania State University
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,190
OpenAlex ID: W4417435312