High-Entropy Oxides: Multifunctionality Enabled through Chemical Disorder*

Entropy engineering offers access to a vast, unexplored materials discovery space by utilizing configurational entropy as a thermodynamic driver towards new multicomponent crystalline solids. Our interdisciplinary team within the Materials Research Science and Engineering Center (MRSEC) at Penn State explores high-entropy oxide (HEO) materials in which the cation sublattices are occupied by many elements at random. The ability to stabilize elements in unusual states within the high-entropy matrix offers an attractive opportunity for functional property engineering in complex oxides, specifically ionic and transparent conductors, relaxor ferroelectrics, and strongly correlated materials. Our interdisciplinary team utilizes first-principles computational predictions to accelerate the discovery of novel HEO compositions as well as for tuning and understanding of functional properties. The combination of recent improved functionals as well as uniquely defined descriptors allow us to traverse the complex HEO composition space in a tractable manner. Our team's efforts hope to push the materials discovery frontier beyond the classical realm of enthalpic stability by utilizing entropy for the next generation of complex-oxide materials.