The Pbx Sn1−xTe pseudobinary alloys are promising materials for infrared detection and thermoelectric applications. They are high mobility semiconductors and exhibit, an energy gap which depends upon alloy composition and temperature and vanishes for × ≃ 0.6−0.7. It is therefore of interest to set up methods to determine the actual composition especially in single crystal samples where the Pb/Sn ratio cannot be fixed a priori or cannot be kept constant along the final sample.
V. Fano, C. Ghezzi, and L. Zanotti, "A Simple X-ray Fluorescence Method for Determining the Composition of Pbx Sn1–x Te Pseudobinary Alloys," Appl. Spectrosc. 30, 359-361 (1976)