Effects of Mn substitution on the thermoelectric properties of the electron-doped perovskite Sr_1-xLa_xTiO₃

We have tried to improve the n-type thermoelectric properties of the electron- doped Perovskite Sr_1-xLa_xTiO₃ by a Mn substitution. The 1 ~ 2 % Mn substitution enhances the Seebeck coefficient (S) and reduces the thermal conductivity (κ) by about 50 % at room temperature (RT) without largely increasing the resistivity for the 5 % electron-doped SrTiO₃. Consequently, the power factor at RT keeps a large value comparable to that of Bi₂Te₃ and the dimensionless figure-of-merits at RT increases twofold by the slight Mn substitution. Such a large reduction of κ at RT is perhaps due to the effect of Jahn-Teller active Mn³⁺ ions, around which dynamical local lattice distortion may occur.