Abstract: A series of In-doped β-Zn₄Sb₃-based materials with nominal compositions of Zn₄Sb_3-xInx (0-0.08, ?x=0.02) by substituting Sb with In were designed in the paper. The single-phase In-doped β-Zn₄Sb₃-based bulk materials with no cracks were prepared by the combination of vacuum melting, furnace cooling and spark plasma sintering techniques. The electrical and thermal transport properties of Zn₄Sb_3-xIn_x in the temperature range of 300-700 K indicate that the In substitution for Sb in Zn₄Sb₃ compound brought the remarkable enhancement in carrier concentration and electrical conductivity, the almost complete vanishing of instinct excitation under high temperature, and the significant reduction in the lattice thermal conductivity. The lattice thermal conductivity for x=0.04 and 0.08 samples is very low and only about 0.21 W/(m·K) at 700 K. All In-doped β-Zn₄Sb₃-based bulk materials had higher ZT values as compared to undoped beta-Zn4Sb3 bulk material. A large ZT value of 1.13 has been achieved for Zn₄Sb_2.94In_0.06 at 700 K that increased by 69%.

Key words: thermoelectric materials, beta-Zn₄Sb₃, In-doping, electrical and thermal transport