Thermoelectric Properties of Heavily Doped Polycrystalline SrTiO3

Abstract

The thermoelectric properties of the n-type Sr deficient polycrystalline SrTiO3 singly or co-doped with Dy and Nb were systematically investigated. The Nb doped samples prepared in forming gas have a solubility limit at about 20 at% against 8 at% of Dy. All prepared samples have metallic behavior of the electrical conductivity above 300°C. The Nb doped samples can reach a high value of electrical conductivity comparable to early reported [5] La-doped ones, however Dy doped samples have a lower thermal conductivity. The behavior of the Seebeck coefficient of Nb and Dy singly doped samples as a function of doping concentration is the same. The containing 4 at% Dy sample heavily co-doped with Nb has a lower thermal conductivity while keeping a high value of electrical conductivity. The highest value of the dimension less figure of merit is about 0.24 at 1273K for the co-doped sample with 4 at% Dy and 20 at% Nb.