Ultralow thermal conductivity and high thermopower of a novel high-entropy (Sr0.2Ba0.2La0.2Eu0.2Pb0.2)Nb2O6 with tungsten bronze structure

Abstract

High-entropy oxides (HEOs) have been extensively investigated as potential materials for thermoelectric applications. Here, a novel high-entropy (Sr0.2Ba0.2La0.2Eu0.2Pb0.2)Nb2O6 with a tungsten bronze structure was synthesized by solid-state method at high temperature, and tested its thermoelectric properties. The XRD, SEM-EDS, and TEM results showcase the successful integration of multi-component cations into the A site, yielding a single-phase material. The intrinsic thermal conductivity of this material is relatively low, measuring 0.78 W·m−1·K−1 at 323 K, thereby demonstrating exceptional thermal insulation behavior. This can be attributed to the highly disordered arrangement of multi-component cations with a distinctive high entropy configuration. At T = 1073 K, the high-entropy ceramic possesses the maximum power factor of 426.50 mW·m−1·K−2. As a result, an impressive thermoelectric figure of merit, ZT = 0.26, was achieved at 1073 K due to synergistic improvements in both electron transport and phonon scattering enabled by the high-entropy engineering strategy.