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 synthesis method for preparing Half-Heusler thermoelectric materials, comprising
(1) preparing appropriate amounts of single elemental powders A, B and X in a 1:1:1 stoichiometric ratio, mixing the powders in an agate mortar and then cold-pressing into a pellet,
(2) sealing the pellet in a silica tube under a pressure of 10 −3 Pa,
(3) initiating a synthesis by point-heating a small part of the pellet,
(4) cooling down the pellet to room temperature in air or quenching the pellet in salt water,
(5) crushing the pellet into fine powder, and
(6) sintering the fine powder by plasma activated sintering (PAS).
2. The synthesis method according to claim 1 , wherein A is an element selected from elements in IIIB, IVB, and VB columns of the periodic table; B is an element selected from elements in VIIIB column of the periodic table; X is an element selected from elements in IIIA, IVA, VA columns of the periodic table; and the sintering is performed with a temperature above 850° C. and a pressure from about 30 MPa to about 50 MPa.
3. The synthesis method according to claim 1 , wherein element A is selected from one of the following: Ti, Zr, Hf, Sc, Y, La, V, Nb, and Ta; element B is selected from one of the following: Fe, Co, Ni, Ru, Rh, Pd, and Pt; and X is selected from one of the following: Sn, Sb, and Bi.