In situ observation of eutectoid reaction forming a PbTe-Sb2Te3 thermoelectric nanocomposite by synchrotron X-ray diffraction

In situ high-temperature powder X-ray diffraction experiments have been performed on Pb10.5Sb31.6Te57.9 using a synchrotron X-ray source to observe the eutectoid reaction from Pb2Sb6Te11 to PbTe and Sb2Te3. Molar fractions of the constituent phases and fraction transformed were obtained as functions of time. The experimental fraction transformed vs. time curve were well fitted by the Kolmogorov-Johnson-Mehl-Avrami equation with an Avrami index n = 1.4. The small n value suggests that the growth of the new phases PbTe and Sb2Te3 is one-dimensional