Thermoelectrical properties of lutetium-doped Bi2Te3 bulk samples prepared from flower-like nanopowders

Lutetium-doped Bi2Te3 flower-like nanopowders were synthesized by hydrothermal method. The flower-like nanopowders were hot pressed into bulk pellets and the doping effects of lutetium on the thermoelectrical properties were investigated. The results show that the doping of lutetium can reduce the electrical resistivity greatly, while does not reduce the Seebeck coefficient too much, therefore results in a high power factor. Because the mass of the lutetium atom is close to the mass of the bismuth atom, replacing bismuth by lutetium will not increase the frequency of phonons greatly, which is helpful to remain a lower thermal conductivity. As a result of the combining effect of the lutetium doping and nanostructure of the sample, figure of merit (ZT) for the Lu0.1Bi1.9Te3 sample can reach a high value 1.7 at 373 K.