A study of GeTe doped with Pb and Bi (Ge0.86Pb0.1Bi0.04Te), used as a thermoelectric material, after heat treatment at 600 and 820 K demonstrates the potential and challenges of determining the chemical and phase composition of the matrix and precipitates using X-ray diffraction and analytical electron microscopy. The main phase is rhombohedral R3m GeTe (over 90 wt %); cubic GeTe (up to 5 wt %), cubic Ge (up to 2 wt %), and trace amounts of germanium oxide have been identified. The distribution of Pb and Bi impurities in the matrix crystal and secondary phase precipitates has been determined.
Suvorova et al. (Sun,) studied this question.