High entropy engineering boosts thermo-mechanical properties of rare-earth tantalates: Influences of cocktail effects

High entropy engineering has been widely used to optimize properties of various materials, and we improve comprehensive performance of rare-earth tantalates RETaO4 (RE is rare earth) by changing configurational entropy in this work. Four medium/high entropy RETaO4 (M/HERT) are successfully prepared, and the variations of disorders and distortion degree of lattices with the increasing configurational entropy are described in detail. It is revealed that M/HERT with the highest configurational entropy does not correspond to the best comprehensive properties. Unexpected variations in properties of M/HERT compared to RETaO4 are observed. By comparing with values obtained from rule of mixture (ROM), it is believed that the cocktail effect exists in M/HERT. The synergistic optimizations of thermomechanical properties are realized, including reducing thermal conductivity, increasing thermal expansion coefficients (TECs), and enhancing mechanical properties. M/HERT exhibit excellent high temperature stability and provide a good thermal insulation gradient, which is significant for hightemperature applications of RETaO4. This work serves as an important part for thermal barrier coatings materials with high working temperatures and low thermal conductivity. (c) 2024 The Authors. Published by Elsevier B.V. on behalf of The Chinese Ceramic Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).