Thermoelectric materials synthesized by self-propagating high temperature synthesis process and methods thereof
The disclosure relates to thermoelectric materials prepared by self-propagating high temperature synthesis (SHS) process combining with Plasma activated sintering and methods for preparing thereof. More specifically, the present disclosure relates to the new criterion for combustion synthesis and the method for preparing the thermoelectric materials which meet the new criterion.
1. A method of preparing a thermoelectric material, comprising:
1) weighing powders of reactants including Bi 2 O 3 , PbO, Bi, Cu, and Se according to a stoichiometric ratio of Bi 2 O 3 :PbO:Bi:Cu:Se=(1−p):3p:(1−p):3:3, where p=0, 0.02, 0.04, 0.06, 0.08 or 0.1, mixing the powders in an agate mortar, and cold-pressing the powders into a pellet;
2) sealing the pellet in a silica tube under a pressure of 10 −3 Pa, initiating a self-propagating high temperature synthesis (SHS) by point-heating a portion of the pellet wherein, once the SHS starts, a wave of exothermic reactions passes through the remaining portion of the pellet, cooling down the pellet after reaction in air or quenched in salt water to obtain a cooled-down pellet containing Bi 1−p Pb p CuSe; and
3) crushing the cooled-down pellet obtained in step 2) into powder, and sintering the powder with plasma activated sintering (PAS) to form a bulk material, wherein parameters of the PAS include a reaction temperature above 670° C. and a reaction pressure of 30 MPa for 5-7 min, and a final product is a BiCuSeO based thermoelectric material.