Power generation of p-type Ca3Co4O9/n-type CaMnO3 module

Thermoelectric modules composed of eight pairs of p-type Ca_2.7Bi_0.3Co₄O₉ (Co-349) and n-type CaMn_0.98Mo_0.02O₃ (Mn-113) bulks were constructed using Ag electrodes and paste including powder of the n-type oxide. The former bulks were prepared by hot-pressing. On the other hand, the latter were densified by a cold isostatic pressing (CIP) technique and sintered in atmospheric pressure. Dimensions of both oxide legs are 5 mm wide and thick and 4.5 mm high. An alumina plate is used as a heated substrate for power generation, and there is no alumina plate on the other side of the module. This module can generate up to 1.0 V and 0.17 W of open circuit voltage and maximum power, respectively, at a hot-side temperature of 897 K and a temperature difference of 565 K in air. But internal resistance reaches at value of 1.5 Omega which is about 6 times higher than the calculated one from resistivity of both p and n-type bulks