Synthesis And Thermoelectric Properties Of β-Zn₄Sb₃

is one of the promising thermoelectric materials in the moderate temperature range. The research of producing crack-free bulk β-Zn₄Sb₃ has attracted substantial interest, as well as using second phase and doping to improve thermoelectric properties.In this thesis, Single-phase β-Zn₄Sb₃ and Zn_4-xIn_xSb₃ bulk samples were produced by melting in an evacuated quartz ampoule followed by cooling slowly, as well as several samples based on β-Zn₄Sb₃ with different amounts of Zn. Their thermoelectric properties were investigated from 300K to 700K.The distribution of Zn in the samples was observed. The effects of excess Zn and doping atom In on thermoelectric properties of β-Zn₄Sb₃ compound were investigated systematically.The distribution of Zn in the samples was observed and the effects of excess Zn on thermoelectric properties of β-Zn₄Sb₃ compound were investigated systematically. With the amount of Zn inclusion increasing, electrical conductivity and thermal conductivity of the sample increases, and the Seebeck coefficient declines. The excess Zn leads to an obvious improvement to the power factor of the β-Zn₄Sb₃ based materials. The ZT_max of sample is 1.10 at 700K, when the amount of excess Zn is 2at%.With the doping amount of In increasing, the lattice parameter increases. When the nominal composition is Zn_3.75In_0.25Sb₃ and analyzed composition is Zn_3.42In_0.23Sb₃, it reaches solubility limit of In substituting Zn in the β-Zn₄Sb₃, and the lattice parameter becomes 1.2284nm (a) and 1.2464 nm (c). The carrier concentration decreases by In-doping, leading to electrical resistivity and Seebeck coefficient increasing. With In doping amount increasing, thermal conductivity of Zn_4-xIn_xSb₃ decreases. Consequently, the ZT_max of Zn_3.95In_0.05Sb₃ is 1.01 at 700K.