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

Spark plasma sintering (SPS) was applied for preparing dense Ca2.75Gd0.25Co4O9 ceramics, and their thermoelectric properties were investigated from room temperature to 700 degreesC 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 4.8x10(-4) W m(-1) K-2 and ZT=0.23 at 700 degreesC, respectively. (C) 2001 American Institute of Physics.