The effect of Sn substitution for Sb on transport and thermoelectric properties of CrSb_2 at low temperatures

摘要

The Sn doped compounds CrSb_(2_x)Sn_x (0<= x<= 0.05) were synthesized and the effect of Sn substitution for Sb on electrical resistivity, thermopower and thermal conductivity of CrSb_2 were investigated from 7 K to 310K. The results indicate that the temperature dependence of electrical resistivity for CrSb_2 did not change obviously after Sn substitution for Sb. However, the magnitude of the resistivity for CrSb_(2-x)Sn_x decreased monotonically with increasing Sn content. Moreover, absolute value of thermopower |S| decreased continuously with increasing Sn content although its temperature behavior was not influenced substantially by Sn doping. The decrease of both the resistivity and |S| could be ascribed to the increase in electron concentration caused indirectly by Sn substitution for Sb. Additionally, experiments showed that low-temperature lattice thermal conductivity (below approx 100 K) of CrSb_(2-x)Sn_x generally decreased with increasing Sn content, which could be explained as an enhancement of phonon scattering by increased number of Sn atoms. The thermoelectric figure of merit, ZT, of doped compounds CrSb_(2-x)Sn_x (x>0) decreased as compared to that of un-doped CrSb_2 due to substantial decrease in |S| after doping. Present results suggest that thermoelectric properties of CrSb_2 cannot be enhanced by Sn substitution for Sb.