Intriguing metal-semiconductor transport properties on Se-substituted β-Zn4Sb3 compounds

Among the numerous thermoelectric compounds, beta-Zn4Sb3 has gained significant interest as a promising thermoelectric material due to its effective working temperature range and enhanced figure of merit (ZT) values. In this work, the effect of Se doping in beta-Zn4Sb3 system has been studied. The structure refinement of the prepared Zn3.9Se0.1Sb3 solid solution was carried out using Rietveld refinement analysis, which confirms that the compound crystallizes in hexagonal rhombohedric structure with R-3c space group. Temperature-dependent electrical conductivity (sigma) of the sample has been measured in the temperature range of 300-610 K. At room temperature, the electrical conductivity value of the sample was found to be high (similar to 1919 S m(-1)) and it tends to decrease upon increasing the temperature up to 514 K and thereafter slightly increases, which indicates the typical metallic to semiconductor transition behaviour of the prepared compound. The positive Hall coefficient (R-H) value reveals that the holes are the dominant charge carriers (p-type) in the prepared sample. The power factor value (sigma S-2) of the sample increases linearly with increase in temperature up to 610 K. Hence the Se substitution in pristine Zn4Sb3 possesses greater effect in inducing superior thermoelectric power factor values. Temperature-dependent total thermal conductivity (kappa(total)) of Zn3.9Se0.1Sb3 sample is measured in the temperature range of 300 to 610 K. At room temperature, the kappa(total) value of the sample was found to be very low (similar to 1 Wm(-1) K-1) and it decreases linearly with increasing the temperature. At 610 K, the sample shows merely ultra-low-thermal conductivity value (similar to 0.6 Wm(-1) K-1). A peak ZT value of similar to 0.3 was obtained in Zn3.9Se0.1Sb3 solid solution at 610 K, which was found to be quite competitive with the current thermoelectric materials.

Automated summary

In this study, the effect of Se doping on the beta-Zn4Sb3 system was investigated. The sample was found to crystallize in a hexagonal rhombohedral structure. The electrical conductivity of the sample exhibited typical metallic to semiconductor transition behavior. The dominant charge carriers in the sample were found to be holes (p-type). The power factor of the sample increased linearly with temperature. The total thermal conductivity of the sample decreased linearly with temperature and showed a low value at 610K. The ZT value of the sample reached 0.3 at 610K, which is competitive with current thermoelectric materials.