The effect of Sr addition on the electrical properties of BaZn2Sb2 Zintl compounds

Abstract

Sr doped BaZn2Sb2 polycrystalline materials with nominal compositions of Ba1−xSrxZn2Sb2 (x = 0.0, 0.25, 0.5) were prepared by synthesizing single crystals using a Sn-flux method followed by vacuum melting. The materials were characterized by powder X-ray diffraction and scanning electron microscopy equipped with electron energy dispersive spectroscopy, respectively. The electrical conductivity and Seebeck coefficient of the materials from room temperature to 773 K were measured. The electrical conductivity of all the materials decreased with increasing temperature and turned to increase with increasing temperature when temperature is above ~600 K, while the Seebeck coefficient increased with increasing temperature and turned to decrease with increasing temperature when temperature is above ~580 K. The electrical conductivity and Seebeck coefficient both increased after doping Sr into BaZn2Sb2. The maximum power factor for the sample with nominal composition of Ba0.5Sr0.5Zn2Sb2 reached 10.67 μW cm−1 K−2, which was about five times as high as that of the pure BaZn2Sb2.