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

Abstract

The thermoelectric properties of ceramics with composition A0.98La0.02MnO3-? 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-? (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-?. 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-? 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-? reaching ?1W/(m?K) combined with a high Seebeck coefficient, ?290 ?V/K. The present data represent a valuable basis for further development of these materials with respect to applications in thermoelectric devices.