Thermodynamic assessments of the Sb–La and Sb–Tb systems

In this work, thermodynamic assessments of the Sb–La and Sb–Tb binary systems have been carried out by using the CALPHAD method on the basis of the experimental data including thermodynamic properties and phase equilibria. The Gibbs free energies of the solution phases (liquid, fcc, bcc, hcp, and dhcp) were described by the subregular solution model with the Redlich–Kister equation. The intermetallic compounds, La2Sb, La3Sb2, LaSb, and LaSb2 in the Sb–La system and Sb2Tb, α - SbTb , β - SbTb , α -Sb3Tb4, β -Sb3Tb4, and Sb3Tb5 in the Sb–Tb system, were treated as stoichiometric phases. A consistent set of thermodynamic parameters has been derived for describing the Gibbs free energy of each solution phase and intermetallic compound in the Sb–La and Sb–Tb systems. A good agreement between the calculated results including phase diagrams and thermodynamic properties and the experimental data in the Sb–La and Sb–Tb systems is obtained.