Thermoelectric properties and stability of nanostructured chromium disilicide CrSi₂

CrSi₂ alloy presents a strong interest for thermoelectric applications; however, its thermal conductivity is still too high and limits strongly its figure of merit. By combining experiment and modeling, we show that the nanostructuring of CrSi₂ leads to a strong decrease in the thermal conductivity without affecting much the electronic transport properties. The thermal conductivity of nanostructured CrSi₂ (∼45 nm) has also been determined as a function of the density. We predict that it would be about 5.5 W/mK at RT for a 100% dense sample, i.e., twice smaller than in bulk samples. We also give for the first time, a prediction of the effect of alloying on the thermal conductivity using the Callaway-Klemens model. To consider final applications, it is necessary to also investigate the thermal stability of nanostructured compounds. We show that grain coarsening of nanostructured CrSi₂, even if it remains limited, happens above 1073 K and will deserve further attention.