Thermodynamic description of the binary Ag–Ga system

The AgGaSe2 as well as AgGaS2 has been showed to be efficient frequency doubling crystals for infrared radiation such as the 10.6 μm CO2 laser. The production of these crystals needs good knowledge of the phase relationship. The thermodynamic description of the binary Ag–Ga system has been chosen as a first step for the description of the Ag–Ga–Se and Ag–Ga–S systems. The Calphad approach has been used for this modeling. Good agreement between experimental data and calculated values has been found.

Research highlights▶ Using new available experimental information about enthalpy of mixing and activity of Ga in liquid phase. ▶ Using the substitional solution for the description of the liquid phase. Previous proposition of the modeling of the liquid Ag–Ga used associate solution model, what is, in our humble opinion, wrong, because neither enthalpy of mixing nor activities show strong interaction between atoms in liquid phase. ▶ Using the (Ag)2:(Ga,Ag,Va)1 model for the description of the ordered HCP phase, what is in agreement with XRD study done by Gunneas et al.