Transport and thermoelectric properties of CrSb2−xTex at low temperatures

Substitutional compounds CrSb2−xTex (0 ≤ x ≤ 0.05) were synthesized and the effects of Te substitution on transport and thermoelectric properties of CrSb2−xTex were investigated from 7 K to 310 K. It was established that the resistivity ρ, absolute value of thermopower |S| and thermal conductivity decrease with increasing Te content. The decrease of the resistivity ρ and absolute value of thermopower |S| could be mainly explained by an increase in electron concentration due to Te substitution for Sb, while the decrease of thermal conductivity of CrSb2−xTex could be caused by the enhancement of phonon scattering by the dopant. Besides, it was discovered that a transition from the semiconducting state (0.01 < x) to the metallic state (x > 0.01) occurred within the Te contents 0.01 < x < 0.02 owing to heavy doping. As a result, thermoelectric figure of merit, ZT, of the properly doped CrSb2−xTex compounds (x = 0.005, 0.01, 0.03 and 0.05) was improved at T > ∼180 K. Specifically, at 310 K the ZT value of CrSb1.97Te0.03 is ∼27% larger than that of CrSb2, indicating that thermoelectric properties of CrSb2 can be improved by an appropriate substitution of Te for Sb.