Formation of 7 layer structure in n-type Bi2(Te0.95Se0.05)3 thermoelectric compound fabricated by gas atomizing and hot extrusion process

The microstructure of n-type Bi2(Te0.95Se0.05)3 thermoelectric compound fabricated by gas atomization and hot extrusion was analyzed using transmission electron microscopy, particularly by high resolution transmission electron microscopy on layered structures. The sequence of the five atomic layers, i.e. Te–Bi–Te–Bi–Te, corresponded to one quintet along c-axis of the Bi2Te3 crystal structure. On the other hand, the seven atomic layers occur in the sequence Te–Bi–Te–Bi–Te–Bi–Bi corresponding to one septet of Bi4Te3 crystal structure and can be described by insertion of two Bi layers between quintets of Bi2Te3 structure.