High entropy engineering boosts thermo-mechanical properties of rare-earth tantalates: Influences of cocktail effects
Luyang Zhang, Lin Chen, Jiankun Wang, Yuxuan Zhang, Yanhui Chu, Jing Feng
Abstract
High entropy engineering has been widely used to optimize properties of various materials, and we improve comprehensive performance of rare-earth tantalates RETaO 4 (RE is rare earth) by changing configurational entropy in this work. Four medium/high entropy RETaO 4 (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 RETaO 4 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 thermo-mechanical 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 high-temperature applications of RETaO 4 . This work serves as an important part for thermal barrier coatings materials with high working temperatures and low thermal conductivity. • Radiative thermal conductivity of M/HERT is 0.11 W K −1 m −1 at 900 °C. • Samples have high TECs (10.48 × 10 −6 K −1 ) and low modulus (119.1 GPa). • Sample with the highest configurational entropy does not show the best properties, and cocktail effects cause unpredictable changes.