Preparation and Thermoelectric Properties of Pb_1–x Fe _x Te Alloys Doped with Iodine

Abstract

This is the first systematic report on the preparation and thermoelectric properties of n-type Pb_1–x Fe _x Te alloys. Iodine-doped n-type Pb_0.85Fe_0.15Te polycrystalline was prepared by melting and hot-pressing techniques. The morphology and phase structure of the prepared materials were analyzed by scanning electron microscopy and x-ray diffraction, which indicated that the samples possessed a rock-salt crystal structure and showed a biphase structure. The major phase was the polycrystalline PbTe compound and the second phase was the FeTe compound. The FeTe nano-/micro-precipitates were homogeneously distributed in the PbTe matrix, which is beneficial for the reduction of the lattice thermal conductivity. The effects of the iodine content on the thermoelectric properties of I-doped Pb_0.85Fe_0.15Te have been investigated. The measurement results of electrical resistivity, carrier concentration, Seebeck coefficient, and thermal conductivity in the temperature range of 300–850 K indicate that the thermoelectric transport properties of the obtained samples are sensitive to the iodine content. When the concentration of iodine is about 0.6 at.%, the maximum dimensionless figure-of-merit value of ∼0.65 at 800 K was obtained.