Response of p-type and n-type Half-Heusler thermoelectric materials to fast neutron irradiation

Abstract

The thermoelectric materials working in radioisotope thermoelectric generators or space reactor power system will be exposed to neutron irradiation in space missions. Herein, the influences of neutron irradiation with doses of 1013n/cm2 and 1015n/cm2 on the transport properties of p- and n-type Half-Heusler thermoelectric alloys were investigated. It was found that, neutron irradiation showed negative effects on thermoelectric properties of p-type Hf0.5Zr0.5CoSb0.85Sn0.15 and p-type Hf0.5Ti0.5CoSb0.85Sn0.15. But neutron irradiation had no effects on thermoelectric properties of n-type Hf0.5Zr0.5NiSn0.985Sb0.015 and n-type ZrNiSn0.985Sb0.015. After 1015n/cm2 neutron irradiation, the electrical conductivity, power factor and ZT of p-type Half-Heusler alloys decreased by 7–22%, which was caused by the decreased carrier concentration. However, the radiation-induced changes in the thermoelectric properties proved to be essentially healed by annealing at 773 K ~ 873 K. The anti-annealing effects were also studied.