Influence of multi-sintering on the thermoelectric properties of Bi2Sr2Co2Oy ceramics

Bi 2 Sr 2 Co 2 O y ${\mathrm{\text{Bi}}}_2{\mathrm{\text{Sr}}}_2{\mathrm{\text{Co}}}_2{\mathrm{\text{O}}}_y$ ceramic samples have a structure similar to phonon glass electronic crystals, and their thermoelectric properties can be effectively adjusted through repeated grinding and sintering. The results show that multi-sintering can make their grain refined and increase their grain boundary, which will effectively increase density and phonon scattering. Finally, multi-sintering can reduce the resistivity and thermal conductivity, thus obviously improve thermoelectric figure of merit ( Z T ) $(ZT)$ of Bi 2 Sr 2 Co 2 O y ${\mathrm{\text{Bi}}}_2{\mathrm{\text{Sr}}}_2{\mathrm{\text{Co}}}_2{\mathrm{\text{O}}}_y$ . The optimum Z T $ZT$ value of 0.26 is achieved at 923 K by the third sintered sample.