Thermoelectric Conversion Material

A thermoelectric conversion material comprising a full Heusler alloy represented by the following composition formula (Formula 2):

• (Fe1−xK1x)2+α(Ti1−βM1β)1−α+γAl1−γ (Formula 2)
• wherein K1 represents at least one element selected from the group consisting of Group 7 elements, Group 8 elements except for Fe, and Group 9 elements;
• M1 represents at least one element selected from, the group consisting of V, Nb and Ta;
• x satisfies the relation:
• 0<x<0.5;
• α satisfies the relation:
• 0<α≦0.42;
• β satisfies the relation:
• 0≦β<0.75;
• when the number of valence electrons of K1 is designated, as k1, and the number of valence electrons of M1 is designated as m1,
• the VEC, which is the valence electron concentration per atom of the full Heusler alloy, is represented by the following mathematical formula (Expression 2) as a function of x, α, β, and γ:
• VEC(x,α,β,γ)=[{8×(1−x)+k1×x}×(2+α)+{4×(1−β)+m1×β}×(1−α+γ)+3×(1−γ)]/4 (Expression 2);
• and
• the VEC satisfies the relation:
• 5.91≦VEC<6.16.

A thermoelectric conversion material comprising a full Heusler alloy represented by the following composition formula (Formula 3):

• Fe2+α((Ti1−γK2γ)1−βM1β)1−α+γAl1−γ (Formula 3)
• wherein K2 represents at least one element selected from, the group consisting of Group 4 elements except for Ti, Group 6 elements, and Group 7 elements;
• M1 represents at least one element selected from the group consisting of V, Nb, and Ta;
• y satisfies the relation:
• 0<y<0.5;
• α satisfies the relation:
• 0<α≦0.42;
• β satisfies the relation:
• 0≦β<0.75;
• when the number of valence electrons of K2 is designated as k2, and the number of valence electrons of M1 is designated as m1,
• the VEC, which is the valence electron concentration per atom of the full Heusler alloy, is represented by the following mathematical formula (Expression 3) as a function of y, α, β, and γ:
• VEC(y,α,β,γ)=[8×(2+α)+{4×(1−y)×(1−β)+k2×y×(1−β)+m1×β}×(1−α+γ)+3×(1−γ)]/4 (Expression 3);
• and
• the VEC satisfies the relation:
• 5.91≦VEC<6.16.