Thermodynamic description of the Holmium-Germanium binary system

The Holmium-Germanium system was thermodynamically assessed by the CALPHAD technique based on the available experimental data including the thermodynamic properties and phase equilibria. The solution phases, i.e. liquid, hcp_A3 (Ho), and diamond_A4 (Ge), were described by the substitutional solution model with the Redlich-Kister equation, and all the intermetallic compounds HoGe 1.7 (_LT and _HT), HoGe 1.8 , HoGe 2.7 , Ho 11 Ge 10 , Ho 3 +Ge 4 , Ho 5 Ge 4 , HoGe, and HoGe 1.5 (_LT and _HT) in the Holmium-Germanium system were treated as stoichiometric phases. The compound with a homogeneity range Ho 5 Ge 3 , is modeled using two sublattices as (Ho,Ge) 0.375 (Ho,Ge) 0.625 . A set of self-consistent thermodynamic parameters for the Holmium-Germanium system was finally obtained. The calculated phase diagram and thermodynamic properties agree reasonably with the literature experimental data.