Enhancing the thermoelectric properties of Bi2Ba2Co2Oy by dispersing SiC nanoparticles based on Na element doping

In this work, Bi2Ba2Co2Oy + v wt% SiC (v = 0.00, 0.025, 0.05, 0.1, 0.2) and Bi1.975Na0.025Ba2CO2Oy + w wt% SiC (w = 0.00, 0.025, 0.05, 0.1, 0.2) ceramic samples were synthesised. The increase in the carrier concentration caused by a small amount of Na element doping leads to a decrease in the resistivity and Seebeck coefficients. The lattice distortion caused by Na element doping decrease the sample thermal conductivity. After adding SiC nanoparticles, the resistivity can be reduced further. Especially more phonons are scattered by more grain boundaries, which leads to reduced thermal conductivity. The Seebeck coefficients increase slightly due to the low energy carrier scattering effect. Considering the influence of these two factors, dispersing SiC particles on the basis of Na element doping can effectively improve the thermoelectric performance of Bi2Ba2Co2Oy-based samples. The ZT value of the Bi2Ba2Co2Oy + 0.1 wt% SiC sample reaches a maximum value of 0.21 at 923 K, 26.6% higher than the Bi1.975Na0.025Ba2Co2Oy sample and 93% higher than the pure Bi2Ba2Co2Oy sample.