Effect of Ca and/or Mn substitution on thermoelectric properties of SrTiO3

Thermoelectric properties have been investigated for Sr 0.5 Ca 0.5 Ti 1-x Mn x O 3 ( x = 0.25, 0.5, 0.75) and Sr 0.75 Ca 0.25 Ti 0.75 Mn 0.25 O 3 perovskite polycrystalline samples synthesized by solid-state reaction method. Following physical properties such as thermal conductivity, electrical resistivity, Seebeck coefficient, power factor and figure of merit (ZT) were measured. The substitution of Ca 2+ in Sr 2+ site or/and mixed valence Mn in Ti site creates appreciable enhancement in the thermoelectric properties with an increase of ZT from 0.5 to 0.69 at room temperature. The origin for the enrichment of ZT of the investigated samples around room temperature is due to substitution induced distortion in the cubic lattice.