High-entropy (Ca_0.2Sr_0.2Ba_0.2La_0.2Pb_0.2)TiO₃ perovskite ceramics with A-site short-range disorder for thermoelectric applications

Novel high-entropy perovskite-type (Ca_0.2Sr_0.2Ba_0.2La_0.2Pb_0.2)TiO₃ (CSBLP) ceramics with cubic structure of Pm-3m space group were successful prepared by solid-state reaction method. Results of XRD, SEM-EDS, HRTEM confirmed a homogeneous distribution and equimolar arrangement of multicomponent cations on the A-site. The high-entropy CSBLP ceramics showed long-range structural order and short-range chemical disorder with widely dispersed nanoscale grains varying sizes of 4-6 nm in the microstructure. Because of increased configurational entropy, the CSBLP ceramic has an enhanced Seebeck coefficient (|S|=272 μV/K at 1073 K) and low thermal conductivity (κ=1.75 W/m•K at 1073 K) when annealed at 1300 °C. This work demonstrates the possibility of effectively reducing thermal conductivity and improving the performance of thermoelectric oxides through high-entropy composition design.