Thermal conductivity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>CaSiO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> perovskite at lower mantle conditions
Zhen Zhang, Dong‐Bo Zhang, Kotaro Onga, Akira Hasegawa, Kenji Ohta, Kei Hirose, Renata M. Wentzcovitch
Abstract
Thermal conductivity ($\ensuremath{\kappa}$) of mantle minerals is key to understanding dynamics in the deep Earth. It controls the style of mantle convection and the timescale of cooling both the mantle and the core. Cubic ${\mathrm{CaSiO}}_{3}$ perovskite (CaPv) is the third most abundant mineral in the lower mantle ($7\phantom{\rule{0.28em}{0ex}}\mathrm{vol}%$). Despite its importance, no theoretical or experimental estimate of CaPv's $\ensuremath{\kappa}$ is available. Theoretical investigations of its properties are challenging because of its strong anharmonicity. Experimental measurements at relevant pressures and temperatures are equally challenging. Here we present ab initio results for CaPv's $\ensuremath{\kappa}$ obtained using the phonon quasiparticle approach to address its strong anharmonicity. We also offer experimental measurements of $\ensuremath{\kappa}$ up to 67 GPa and 1950 K. Predictions and measurements are in good agreement and reveal a surprisingly large $\ensuremath{\kappa}$ for cubic CaPv that can be explained on the basis of its high crystal structure symmetry. Despite its relatively low abundance, CaPv's $\ensuremath{\kappa}$ increases the lower mantle $\ensuremath{\kappa}$ by $\ensuremath{\sim}10%$, if accounted for. $\ensuremath{\kappa}$ of mantle regions enriched in subducted crustal materials will be more strongly impacted.