Electrical Transport Properties of Single-Crystalline β-Zn4Sb3 Prepared Through the Zn-Sn Mixed-Flux Method

Abstract

β-Zn4Sb3 is a promising p-type thermoelectric material for utilization in moderate temperatures. This study prepares a group of single-crystalline β-Zn4Sb3 samples using the Zn-Sn mixed-flux method based on the stoichiometric ratios of Zn4+x Sb3Sn y . The effect of Zn-to-Sn proportion in the flux on the structure and electrical transport properties is investigated. All samples are strip-shaped single crystals of different sizes. The actual Zn content of the present samples is improved (>3.9) compared with that of the samples prepared through the Sn flux method. Larger lattice parameters are also obtained. The carrier concentration of all the samples is in the order of over 1019 cm−3. With increasing Sn rate in the flux, this carrier concentration decreases, whereas mobility is significantly enhanced. The electrical conductivity and Seebeck coefficients of all the samples exhibit a behavior that of a degenerate semiconductor transport. Electrical conductivity initially increases and then decreases as the Sn ratio in the flux increases. The electrical conductivity of the x:y = 5:1 sample reaches 6.45 × 104 S m−1 at 300 K. Benefitting from the electrical conductivity and Seebeck coefficient, the flux proportion of the x:y = 7:1 sample finally achieves the highest power factor value of 1.4 × 10−3 W m−1 K−2 at 598 K.