Abstract: There is provided a thermoelectric conversion material made of a full-Heusler alloy and capable of enhancing figure of merit. In order to solve the above problem, the thermoelectric conversion material is made of the full-Heusler alloy represented by the following composition formula: (Fe1-xM1x)2+?(Ti1-yM2y)1+?(A1-zM3z)1+?. A composition in a ternary phase diagram of Fe—Ti-A is inside a hexagon having points (50, 37, 13), (45, 30, 25), (39.5, 25, 35.5), (50, 14, 36), (54, 21, 25), and (55.5, 25, 19.5) as apexes. Further, an amount of change ?VEC of an average valence electron number per atom VEC in the case of x=y=z=0 satisfies a relation 0<|?VEC|?0.2 or 0.2<|?VEC|?0.3.

Abstract: The present invention provides a thermoelectric conversion material that is a material comprising elements less poisonous than Te and has a Seebeck coefficient comparable to BiTe. The present invention is a full-Heusler alloy that is represented by the composition formula Fe2+?Ti1+ySi1+z and has ?, y, and z allowing the material to fall within the region surrounded by (Fe, Ti, Si)=(50, 37, 13), (50, 14, 36), (45, 30, 25), (39.5, 25, 35.5), (54, 21, 25), and (55.5, 25, 19.5) by at % in an Fe—Ti—Si ternary alloy phase diagram.