Thermodynamic description of the Holmium-Germanium binary system
1 Laboratoire de Thermodynamique et Énergétique, LTE, Université Ibn-Zohr, BP 8106 Agadir, Morocco
2 Laboratoire de Physicochimie de l'État Solide, ICMMO, Université Paris-Sud, 91405 Orsay Cedex, France
Received: 11 July 2016
Revised: 4 August 2016
Published online: 18 April 2017
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 HoGe1.7 (_LT and _HT), HoGe1.8, HoGe2.7, Ho11Ge10, Ho3+Ge4, Ho5Ge4, HoGe, and HoGe1.5 (_LT and _HT) in the Holmium-Germanium system were treated as stoichiometric phases. The compound with a homogeneity range Ho5Ge3, 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.
© EDP Sciences, Springer-Verlag, 2017