Thermoelectric properties of n-type double substituted SrTiO3 bulk materials

A series of La, Ta double substituted Sr1-xLaxTi1-xTaxO3, with x = 0.01, 0.05 and 0.10, and La, Nb double substituted Sr0.90La0.10Ti0.90Nb0.10O3 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 Sr0.99La0.01Ti0.99Ta0.01O3 with a thermoelectric figure-of-merit of 0.13 at 660 K.