Investigation on the thermoelectric properties of nanostructured Cr1-xTixSi2

CrSi2 material is outstanding because of its thermoelectric properties and also because of its many optimization routes. Indeed, its thermal conductivity at room temperature is about 9 W m(-1) K-1 with a ZT of 0.25. In this paper we propose to decrease the thermal conductivity by nanostructuration and compensate the electron scattering by increasing the charge carrier concentration with Ti. The process which permitted to get nanocrystallite of about 14 nm is presented. After cold pressing and sintering the average crystallite size reaches 50 nm with a porosity of 70%. Nanostructuring and porosity to a lesser extent lead to a strong decrease of the thermal conductivity up to 0.9 +/- 0.15W m(-1) K-1 for pure CrSi2. A significant enhancement of the power factor from 1.25 mu W cm(-1) K-2 for pure nano-CrSi2 to 2.5 mu W cm(-1) K-2 for nano-Cr0.90Ti0.10Si2 was obtained. The stability of the different phases is also evaluated by comparing experiments with ab initio calculations. (C) 2012 Elsevier Inc. All rights reserved.