The invention relates to an n-type Cu2Sn3S7-based medium-high temperature thermoelectric
semiconductor and a mechanical alloying preparation technique thereof. The key point of the design of the n-type Cu2Sn3S7-based medium-high temperature thermoelectric
semiconductor lies in that the Sn content is increased on the basis of the compositions of Cu2Sn3S7, and the
chemical formula of Cu2Sn3.5S7 is formed. The mechanical alloying preparation technique of the n-type Cu2Sn3S7-based medium-high temperature thermoelectric
semiconductor comprises the steps that the corresponding quantity of Cu, the corresponding quantity of Sn and the corresponding quantity of S are weighed according to the
chemical formula and placed in a vacuum ball milling tank to be subjected to ball milling for two hours; annealing is conducted for 48 hours in a
vacuum tube at the temperature of 700 DEG C after ball milling; then
powder is taken out and subjected to
discharge plasma spark
sintering in a short time of four minutes for formation; and the highest
sintering temperature is 700 DEG C, the
sintering pressure is 60 MPa, and a Cu2Sn3.5S7 thermoelectric semiconductor is prepared. The
Seebeck coefficient a of the thermoelectric semiconductor at the temperature of 877 K is -698.38 (<mu>V / K), the electric
conductivity s is 1.18'10<3>W<-1>.m<-1>, the heat
conductivity k is 0.43(W.K<-1>.m<-1>), and the maximum thermoelectric optimum value ZT is 1.17. The n-type Cu2Sn3S7-based medium-high temperature thermoelectric semiconductor has the advantages that
pollution and
noise are avoided, the semiconductor can be used for manufacturing medium-high temperature power generation components, operation is reliable, the service life is long, and the preparation technique is simple.