Ca3 − xBixCo4O9 and Ca1 − ySmyMnO3 thermoelectric materials and their power-generation devices



The p-type Ca3 − xBixCo4O9 (p-Co349/Bix) and n-type Ca1 − ySmyMnO3 (n-Mn113/Smy) oxide thermoelectric (TE) materials were synthesized by the self-ignition method and consolidated by a sintering technique. The effects of Bi and Sm dopant partial substitution on TE properties were investigated. At 973 K, the figures of merit, ZT, for p-Co349/Bi0.3 and n-Mn113/Sm0.02 materials are 0.27 and 0.15, respectively. In addition, TE devices containing two pairs of p-Co349/Bi0.3 and n-Mn113/Sm0.02 were fabricated. The technology parameters involved in the fabricating process, including the electrical contact, mechanical connection, and high-temperature durability, were discussed and optimized. The performance of the devices was evaluated in terms of contact resistance, maximum output power, and manufacturing factor (MF). The Pmax and volume power density for the four legs devices reached 51.4 mW and 127.6 mW cm−3 for a ΔT of 525 K, while the contact resistance of 0.21 Ω and a high MF of 66.3% were obtained. Little fluctuant in open-circuit voltage (V0) and internal resistance (Rin) were observed after six-time thermocycling tests, implying a high-temperature durability.