Effects of crystal-alignment and grain shape on the thermoelectric properties of Bi0.5Sb1.5Te3 alloys

We investigated the thermoelectric properties of sintered Bi0.5Sb1.5Te3 alloys containing grains for their alignment, sizes and shapes. The figure of merit can be improved as the result of lower resistivity by increasing the alignment, which is realized by using the spark plasma sintering method and a strong magnetic field. In addition, making the grains more spherical can improve the thermoelectric efficiency as a result of carrier quantum confinement and enhancement of the band gap energy.

► The thermoelectric efficiency of Bi0.5Sb1.5Te3 alloys was improved by increasing the crystalline alignment and by making the grains more spherical in the region of the same volume. This improvement mainly results from the improved thermal conductivity due to the phonon-grain boundary scattering and the band gap enhancement due to the more strong carrier confinement to the measuring direction.