Thermoelectric material and thermoelectric element
Disclosed is a thermoelectric material which is represented by the following composition formula (1) or (2) and comprises as a major phase an MgAgAs type crystal structure: (Ti a1 Zr b1 Hf c1 ) x Ni y Sn 100-x-y composition formula (1); (Ln d (Ti a2 Zr b2 Hf c2 ) 1-d ) x Ni y Sn 100-x-y composition formula (2); (wherein a1, b1, c1, x and y satisfy the conditions of: 0<a1<1, 0<b1<1, 0<c1<1, a1+b1+c1=1, 30≦x≦35 and 30≦y≦35, and Ln is at least one element selected from the group consisting of Y and rare earth elements, and a2, b2, c2 and d satisfy the conditions of: 0≦a2≦1, 0≦b2≦1, 0≦c2≦1, a2+b2+c2=1 and 0<d≦0.3).
1. A thermoelectric material which is a sintered body and represented by composition formula (1) and comprises as a major phase an MgAgAs crystal structure, the sintered body being obtained by melting raw materials to obtain melted raw materials, quenching the melted raw materials to obtain an alloy formed of a metallic lump, pulverizing the alloy to obtain an alloy powder, and monolithic molding the alloy powder by sintering, hot press or SPS method, wherein the composition formula (1) is (Ti a1 Zr b1 Hf c1 ) x Ni y Sn 100-x-y , and
a1, b1, c1, x and y satisfy the conditions of: 0<a1<1, 0.2≦b1≦0.4, 0<c1<1, a1+b1+c1=1, 30≦x≦35 and 30≦y≦35, and
the sintered body has a dimensionless figure-of-merit ZT value of not less than 0.07 at 300° K.
2. The thermoelectric material according to claim 1 , wherein a1 satisfies 0.1≦a1≦0.8.
3. The thermoelectric material according to claim 1 , wherein a1 satisfies 0.2≦a1≦0.4.
4. The thermoelectric material according to claim 1 , wherein c1 satisfies 0.1≦c1≦0.8.
5. The thermoelectric material according to claim 1 , wherein c1 satisfies 0.2≦c1≦0.4.
6. The thermoelectric material according to claim 1 , wherein Ti, Zr and Hf in said composition formula (1) are partially replaced by at least one element selected from the group consisting of V, Nb, Ta, Cr, Mo and W.
7. The thermoelectric material according to claim 1 , wherein Ni in said composition formula (1) is partially replaced by at least one element selected from the group consisting of Mn, Fe, Co and Cu.
8. The thermoelectric material according to claim 1 , wherein Sn in said composition formula (1) is partially replaced by at least one element selected from the group consisting of As, Sb, Bi, Ge, Pb, Ga and In.
9. The thermoelectric material according to claim 1 , wherein the raw materials are placed in a water-cooled copper hearth.
10. The thermoelectric material according to claim 1 , wherein the raw materials are subjected to arc-melting.
11. The thermoelectric material according to claim 1 , wherein the melted raw materials are quenched in the water-cooled copper hearth.
12. A thermoelectric element comprising: p-type thermoelectric material and n-type thermoelectric material, both of which are alternately connected with each other in series, wherein the n-type thermoelectric material comprises the thermoelectric material claimed in claim 1 .