Optimized configuration entropy for synergistic enhancement of thermoelectric performance for SrTiO3-based ceramics

Abstract

High-entropy design has proven effective for optimizing thermoelectric properties, particularly thermal conductivity. However, only appropriate configuration entropy can synergistically enhance thermoelectric performance. Here, La, Nd, Dy and Y are used to modulate configuration entropy of SrTiO₃-based ceramics. Thermodynamic evaluations suggest that (Sr_1–4xLa_xNd_xDy_xY_x)TiO₃ components, with configuration entropy from 1.05 to 4.43 J mol⁻¹ K⁻¹, can form single-phase cubic structures. High electrical conductivity and Seebeck coefficient result in power factor of 1213 μW K⁻² m⁻¹ at 473 K, exceeding 3 times higher than typical high-entropy ceramics. Point defects, mainly inducing stress field fluctuations, cause lattice thermal conductivity of 3.0 W m⁻¹ K⁻¹ at 973 K, rivalling that of high-entropy ceramics. Ultimately, maximum zT value of 0.2 (x = 0.02, 0.025, 0.03) at high-temperatures surpasses most high-entropy ceramics. Hence, configuration entropy from 3.24 to 4.43 J mol⁻¹ K⁻¹ is more conducive for synergistically optimizing electro-thermal transport properties and enhancing zT in (Sr_1–4xLa_xNd_xDy_xY_x)TiO₃ ceramics.