Method for preparing (Bi0.8Sb0.2)2Te3 nano thermoelectric material

The invention discloses a method for preparing a (Bi0.8Sb0.2)2Te3 nano thermoelectric material. The method comprises the following steps of (1) mixing a Bi2Te3 powder material and a Sb2Te3 powder material, and performing mechanical alloying treatment, thereby obtaining a ball-milling material; (2) taking a small part of ball-milling material, putting the ball-milling material into an alumina burning boat of a vacuum atmosphere furnace, filling mixed gas of argon and hydrogen, raising the temperature for performing vapor deposition, and collecting a powder material deposited on an alumina plate, thereby obtaining a vapor deposition material; (3) mixing the ball-milling material and the vapor deposition material according to a mass ratio of 5:1, and performing high-frequency heating and rapid hot press molding, thereby obtaining the (Bi0.8Sb0.2)2Te3 nano thermoelectric material. According to the preparation method, the electronic state density nearby a Fermi level is improved and controlled, and a Seebeck coefficient of the thermoelectric material is improved. Moreover, with nano-scale micro-defects, a scattering effect on phonons is enhanced, the lattice thermal conductivity of the thermoelectric material is reduced, and the thermoelectric performance of the material is greatly improved.