Phase equilibrium and intermediate phases in the Eu–Sb system

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 Eu4Sb3 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, EuSb2 and Eu4Sb3, melt congruently at 1045±10 °C and 1600±15 °C, the Eu2Sb3, Eu11Sb10, Eu5Sb4, and Eu5Sb3 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 Eu4Sb3, the most refractory compound, was determined. The topology of the Eu–Sb phase diagram was considered together with that of the Yb–Sb system.

Graphical abstractThe high-temperature range of the T−x phase diagram for the Eu–Sb system.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The phase relations in the Eu–Sb system were studied over a large composition and temperature scale. ► The liquidus and solidus lines of the T−x diagram were well established using effective techniques. ► In the system, six binary phases are stable and they melt incongruently except EuSb2 and Eu4Sb3. ► Incongruent evaporation was found to be typical of all the phases besides Eu4Sb3.