Thermoelectric properties of Cl-doped In$_{4}$Pb$_{0.01}$Sn$_{0.03}$Se$_{2.9}$Cl$_{x}$ polycrystalline compounds

We investigated thermoelectric properties of Cl-doped polycrystalline compounds of In$_{4}$Pb$_{0.01}$Sn$_{0.03}$Se$_{2.9}$Cl$_{x}$ (x $=$ 0.02, 0.04 and 0.06). The x-ray diffraction measurement shows gradual change of lattice volume for x $\le $ 0.04 without any impurity phases indicating systemic change of Cl-doping. The Cl-doping in the compounds has an effect of increasing carrier concentration and effective mass of carrier resulting in the increase of power factor near 700 K than In$_{4}$Pb$_{0.01}$Sn$_{0.03}$Se$_{2.9}$. Because of the increased electrical conductivity neat 700 K, the thermoelectric figure-of-merit ZT is 1.25 at 723 K for x $=$ 0.04 Cl-doped compound which is relatively high value as n-type polycrystalline materials.