Dispersing Bi₂Mo₂O₉ nanoparticles into Bi_0.5Sb_1.5Te₃ alloys for enhanced thermoelectric figure of merit (ZT) through phonon scattering

Bi₂Mo₂O₉ nanoparticles were introduced into bismuth antimony tellurium (BST) alloys by ball milling, and the composite particles were then fabricated into pellets by hot press for thermoelectric property measurement. Both elemental mapping and TEM image confirmed that Bi₂Mo₂O₉ nanoparticles were evenly distributed among BST matrix. The impacts of Bi₂Mo₂O₉ volume percentage on the electrical resistivity, Seebeck coefficient, thermal conductivity, and thermoelectric figure of merit (ZT) of BST/Bi₂Mo₂O₉ composites were investigated. The results told that the composite presented the highest thermoelectric ZT when Bi₂Mo₂O₉ was 0.3 vol%, which was increased by 12.15% from the ZT of pure BST at room temperature. This could be attributed to the balance between the decreased thermal conductivity and increased electrical resistivity, and phonons could are blocked when charge carriers passing through the dispersed Bi₂Mo₂O₉ nanoparticles.