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

Among the numerous thermoelectric compounds, β-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 β-Zn₄Sb₃ system has been studied. The structure refinement of the prepared Zn_3.9Se_0.1Sb₃ 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 (σ) 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 (~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 (σS²) 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 (κ_total) of Zn_3.9Se_0.1Sb₃ sample is measured in the temperature range of 300 to 610 K. At room temperature, the κ_total value of the sample was found to be very low (~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 (~0.6 Wm⁻¹ K⁻¹). A peak ZT value of ~0.3 was obtained in Zn_3.9Se_0.1Sb₃ solid solution at 610 K, which was found to be quite competitive with the current thermoelectric materials. [ABSTRACT FROM AUTHOR]