Effect of Copper Additions on the Thermoelectric Properties of a Layered Calcium Cobaltite Prepared by Hot Pressing

— Low-porosity layered calcium cobaltite-based ceramics with copper additions have been prepared by hot pressing and their microstructure and electrical transport and thermoelectric properties have been studied. The results demonstrate that the addition of copper particles to the ceramics reduces the average particle size of the Ca 3 Co 4 O 9 + δ phase and the thermoelectric power and porosity of the samples and increases the electrical conductivity and thermoelectric power factor ( P ) of the ceramics. The highest thermoelectric power factor is offered by the hot-pressed ceramic with the composition Ca 3 Co 4 O 9 + δ + 2 wt % Cu ( P 1100 = 521 μW/(m K 2 )), which is a factor of 1.4 higher than that of the basic material Ca 3 Co 4 O 9 + δ having the same thermal history ( P 1100 = 363 μW/(m K 2 )) and more than five times the thermoelectric power factor of low-density Ca 3 Co 4 O 9 + δ ceramics prepared by conventional solid-state reactions.