Phase Stability and Electric Polarization in High-Entropy Oxides for Electrocaloric Refrigeration

The electrocaloric effect is of practical interest to the development of sustainable solid-state refrigeration technologies. High-entropy oxides [1] hold promise for electrocaloric cooling due to the intrinsic thermal stability of their polar phases. In this work, we study the phase stability and electrocaloric performance of the high-entropy perovskite (Na,Bi,Sr,Ba,Ca)TiO₃. To enable the efficient sampling of the configurational space of (Na,Bi,Sr,Ba,Ca)TiO₃, a novel approach is presented in which the Goldsmith tolerance factor of the perovskite structure is calculated along specific crystallographic directions. Preliminary studies suggest that this directional tolerance factor correlates to the mixing enthalpy of high-entropy perovskites and can reliably be used to predict thermodynamic formability. Upon further validation, this methodology may significantly reduce the computational cost and complexity of free-energy calculations in high-entropy perovskites and related crystal structures.

[1] Rost, Sachet, Borman, Moballegh, Dickey, Hou, Jones, Curtarolo, Maria, Nature Communications 6, 8485 (2015)