Enhanced thermoelectric performance of BiSbTe-based composites incorporated with amorphous Si3N4 nanoparticles

Thermoelectric properties of BiSbTe-based composites dispersed with a small amount (<1 vol%) of amorphous Si3N4 (a-Si3N4) nanoparticles (similar to 25 nm) were investigated in the temperature range from 303 K to 483 K. The results indicate that with a-Si3N4 content increasing, the thermopower (S) of the a-Si3N4/BiSbTe composites increases substantially at T < similar to 370 K, due to the decreased carrier concentrations and the enhanced energy-dependent scattering of the carrier at the heterojunction potential. Simultaneously, a-Si3N4 nanodispersion causes similar to 20-30% reduction in thermal conductivity (kappa) owing to phonon scattering of nanoparticles as well as phase boundaries. As a result, high dimensionless figure of merit (ZT) values of up to 1.20 (similar to 303 K) and 1.38 (similar to 383 K) are obtained in Bi0.4Sb1.6Te3 incorporated with only 0.44 vol% a-Si3N4 nanoparticles, demonstrating that the thermoelectric performance of the BiSbTe alloy can be improved effectively through incorporation of a-Si3N4 nanoparticles.