High-entropy alumino-silicides: a novel class of high-entropy ceramics

High-entropy ceramics (HECs) are gaining significant interest due to their huge composition space, unique microstructure, and adjustable properties. Previously reported studies focus mainly on HECs with the multi-cationic structure, while HECs with more than one anion are rarely studied. Herein we reported a new class of HECs, namely high-entropy alumino-silicides (Mo0.25Nb0.25Ta0.25V0.25)(Al0.5Si0.5)2(HEAS-1) with multi-cationic and -anionic structure. The formation possibility of HEAS-1 was first theoretically analyzed from the aspects of thermodynamics and lattice size difference based on the first-principles calculations and then the HEAS-1 were successfully synthesized by the solid-state reaction at 1573 K. The as-synthesized HEAS-1 exhibited good single-crystal hexagonal structure of metal alumino-silicides and simultaneously possessed high compositional uniformity. This study not only enriches the categories of HECs but also will open up a new research field on HECs with multi-cationic and -anionic structure.