Thermoelectric properties of Ruddlesden-Popper phase n-type semiconducting oxides: La-, Nd-, and Nb-doped Sr3 Ti2O7

Abstract

We report herein on Ruddlesden-Popper-type doped Srn+1 TinO3n+1 (n =2) as a potential candidate for n-type thermoelectric (TE) oxides. The TE properties of 5at.% La-, Nd-, and Nb-doped Sr3Ti2O7 polycrystalline ceramics were investigated and the origin of Seebeck coefficient was discussed from the viewpoint of the symmetry of TiO6 octahedra. A significant reduction in the lattice thermal conductivity was observed by the enhancement of phonon scattering at SrO/(SrTiO3)n interfaces originating from the inherent superlattice structure, and the maximum dimensionless figure of merit, ZT ∼0.15, at a 1000K value was obtained in 5at.% La-doped Sr3Ti2O7. © 2007 The American Ceramic Society.