Improved thermoelectric property of cation-substituted CaMnO₃

Single-phase pristine and cation-substituted calcium manganite (Ca_1−xBi_xMn_1−yV_yO_3−δ) polycrystalline samples were synthesized by the solid state reaction technique. Their thermoelectric properties were measured by a set up that was designed and assembled in the laboratory. The Ca_1−xBi_xMn_1−yV_yO_3−δ sample with x = y = 0.04 has shown a power factor (S²σ) of 176 μW/m/K² at 423 K, which is nearly two orders of magnitude higher than that of the pristine sample (2.1 μW/m/K²). The power factor of the substituted oxide remains almost temperature independent as the Seebeck coefficient increases monotonically with temperature, along with the simultaneous decrease in electrical resistivity which is attributed to enhanced electron density due to co-doping of bismuth and vanadium and grain boundary scattering. These cation-substituted calcium manganites can be used as a potential candidate for an n-type leg in a thermoelectric generator (module). (paper)