Phase equilibrium and intermediate phases in the Eu–Sb system

Abstract

Rapid heating rate thermal analysis, X-ray diffraction, fluorescence spectrometry, and differential dissolution method were used to study the high-temperature phase equilibrium in the Eu–Sb system within the composition range between 37 and 96 at% Sb. The techniques were effective in determination of the vapor–solid–liquid equilibrium since intermediate phases except Eu 4Sb 3 evaporated incongruently after melting. A thermal procedure was developed to determine the liquidus and solidus lines of the T−x diagram. Six stable phases were identified: two phases, EuSb 2 and Eu 4Sb 3, melt congruently at 1045±10 °C and 1600±15 °C, the Eu 2Sb 3, Eu 11Sb 10, Eu 5Sb 4, and Eu 5Sb 3 phases melt incongruently at 850±8 °C, 950±10 °C, 1350±15 °C, and 1445±15 °C, respectively. The exact composition shifting of Sb-rich decomposable phases towards Eu 4Sb 3, the most refractory compound, was determined. The topology of the Eu–Sb phase diagram was considered together with that of the Yb–Sb system.