Vacancy site occupation by Co and Ir in half-Heusler ZrNiSn and conversion of the thermoelectric properties from n-type to p-type

摘要

The n-type thermoelectric properties of the half-Heusler compound ZrNiSn can be converted to p-type by the addition of Co and Ir.We found that Co and Ir atoms preferably occupy the vacancy sites instead of substituting at Ni sites. This implies that the phase stabilityof the compound gradually changes towards that of the Heusler compound Zr(Ni,M)2Sn, where M is Co and/or Ir. The occupation ofvacancy sites by Co and Ir atoms leads to a drastic reduction in lattice thermal conductivity owing to the enhancement of phonon scat-tering by the solid solution effect.