Thermoelectric properties of spark plasma sintered Ca2.75Gd0.25Co4O9 ceramics

Abstract

Spark plasma sintering (SPS) was applied for preparing dense Ca2.75Gd0.25Co4O9 ceramics, and their thermoelectric properties were investigated from room temperature to 700 °C in air. The SPS process was effective in obtaining dense Ca2.75Gd0.25Co4O9 ceramics, typically 98% of the theoretical x-ray density, with lower resistivity, without any degradation of the thermoelectric power. The power factor and figure of merit of the spark plasma sintered samples attain 4.8×10−4 W m−1 K−2 and ZT=0.23 at 700 °C, respectively.