The effect of alkaline earth metal substitution on thermoelectric properties of A0.98La0.02MnO3-δ (A=Ca,Ba)

The thermoelectric properties of ceramics with composition A0.98La0.02MnO3-δ are anticipated to vary with the basicity and atomic portion of the alkaline earth metal, A. In the present investigation ceramic powder precursors with composition A0.98La0.02MnO3-δ (A = Ca, Ba) were synthesized by the solid-state method and sintered in air at 1400°C. Seebeck coefficient, electrical and thermal conductivities were characterized for both materials from 100 to 900°C in air. The highest zT of 0.10 at 900°C was reached for Ca0.98La0.02MnO3-δ. The high zT is attributed to the enhanced electronic conductivity (∼90 S/cm at 900°C) due to La doping. zT for Ba0.98La0.02MnO3-δ reached its highest value (0.02) at 800°C corresponding to a low electronic conductivity (∼2 S/cm), while the thermal conductivity was significantly reduced compared to Ca0.98La0.02MnO3-δ reaching ∼1W/(m•K) combined with a high Seebeck coefficient, −290 μV/K. The present data represent a valuable basis for further development of these materials with respect to applications in thermoelectric devices.