Solvothermal synthesis and thermoelectric properties of lanthanum contained Bi-Te and Bi-Se-Te alloys

Novel nano-sized lanthanum contained Bi2Te3 and Bi2Se0.3Te2.7 powders have been synthesized in ethanol at 150 °C for 24 h via solvothermal processes. It was found that alloying of lanthanum in both Bi2Te3 and Bi2Se0.3Te2.7 does not change their crystal structures. The maximal dimensionless figure of merit measured is about 0.11 for La-Bi2Se0.3Te2.7 at 450 K. However, the very low thermal conductivity of 0.4-0.5 W (m K)−1 and the moderate Seebeck coefficient of about 170 μV K−1 indicate the potential to improve the thermoelectric properties of the material by doping optimization.