High thermoelectric performance in nano-SiC dispersed Bi1.6Pb0.4Sr2Co2Oy compounds

Abstract

Thermoelectric materials are widely used in space, solar energy, refrigeration, flexible materials and so on, because they can directly convert electric energy and heat energy into each other. In this paper, the polycrystalline ceramic materials Bi2Sr2Co2Oy (abbreviated as BSCO) were prepared by the conventional solid-phase reaction sintering method, and their thermoelectric properties were optimized under the dual action of cationic Pb2+ substitution and nano-SiC dispersion. The change of Seebeck coefficients after Pb doping is different from that in theory, which does not accord with the coupling trend of the decrease of resistivity with the increase of Seebeck coefficients. This is because Pb doping opens a pseudogap in BSCO system, which leads to the increase of the Seebeck coefficient. Thus the electrical transportation properties of the materials are improved. Nano-SiC dispersion can increase phonon scattering, thus improve the thermal transport properties of the materials. Under the condition of 973 K and q = 0.025, the power factor of Bi1.6Pb0.4Sr2Co2Oy + q wt% SiC (q = 0, 0.025, 0.05, 0.1 and 0.15) system reaches 307 × 10−6 Wm−1K−2, and the dimensionless thermoelectric figure of merit (ZT) value reaches 0.48, which is the maximum in the previously reported BSCO polycrystalline ceramics.