Thermoelectric properties of n-type double substituted SrTiO3 bulk materials

Abstract

A series of La, Ta double substituted Sr_1−xLa_xTi_1−xTa_xO₃, with x = 0.01, 0.05 and 0.10, and La, Nb double substituted Sr_0.90La_0.10Ti_0.90Nb_0.10O₃ for comparison were investigated in this project. Rietveld refinements were performed to check for purity and symmetry reduction. Electronic structure calculations indicate n-type conduction with steep and flat bands in the vicinity of the Fermi level for x = 0.125. Seebeck coefficient, electrical conductivity, and thermal conductivity measurements on hot-pressed and spark-plasma-sintered samples were performed over a wide range of temperatures. Best results were obtained by spark-plasma-sintering of double substituted Sr_0.99La_0.01Ti_0.99Ta_0.01O₃ with a thermoelectric figure-of-merit of 0.13 at 660 K.