Tuning the carrier concentration for thermoelectrical application in the quaternary Heusler compound Co2TiAl(1a degree x )Si x

The family of half-metallic ferromagnets Co2TiZ exhibits exceptional transport properties. The investigated compounds Co2TiAl(1a degree x )Si x (x =0.25, 0.5, 0.75) show Curie temperatures (T Cs) that vary between 250 and 350K, depending on the composition. Above T C the Seebeck coefficient remains constant. This makes them promising candidates for thermoelectric devices such as thermocouples with a tunable working range. The electrical resistivity data show an anomaly at T C which is attributed to changes in the electronic structure and therefore in the carrier concentration.