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Abstract:
The half-Heusler system CoTi1-xYxSb (Y = Sc, V, Mn, Fe) has been
investigated by means of an ab initio-based mean-field model which
provides phase diagrams of alloys. Co(Ti, Y) Sb materials show a
miscibility gap, which leads to spontaneous demixing within a spinodal
region. The results are compared with experimental investigations of
microstructure and transport properties of the alloys. The
thermoelectric properties of the solid solution were investigated
comprehensively by measuring the temperature dependence of the Seebeck
coefficient as well as electrical and thermal conductivity. Compared
with pure CoTiSb, the thermal conductivity of substituted CoTi0.9Y0.1Sb
was significantly reduced by approximately 53% for Y = V. Here, we
report on the effect of phase separation in the Co(Ti, Y) Sb system and
its consequences for the thermoelectric figure or merit.
