New experimental studies on the phase relationship of the Bi–Pb–Te system

Abstract

Knowledge of the phase relationships is crucial in developing thermoelectric materials and allows a better understanding of the properties of the relevant systems. In the present work, we present the liquidus projection of the Bi-Pb-Te system and phase equilibria of the BiTe-PbTe-Bi2Te3 portion at 400 and 520 °C. Alloys were prepared by melting high-purity elements in cleaned quartz tubes and their microstructures were characterized by scanning electron microscopy, electron probe microanalysis, wavelength-dispersive X-ray spectrometer, X-ray diffractometry and differential scanning calorimetry. The binary compound BiTe extends up to 16.7 at.% Pb along BiTe-PbTe at 520 °C. The solubilities of Bi in PbTe were established to be 3.6, 3.8 and 10.8 at.% at 360, 400 and 520 °C, respectively. This work will help to understand the microstructure evolution during preparation and service and promote the designing of the Bi–Pb–Te-based high-performance materials.