Phase stability and structural properties of the K<sub>x</sub>Ca<sub>1-x</sub>N novel ferromagnetic alloy from first-principles

We study the structural properties and phase stability of the KxCa1−xN alloy using the regular-solution model based on the total energy of the mixing. The pseudopotential approach was used along with PBE functional of Perdew, Burke, and Ernzerhof (PBE). We investigated the bond-lengths distribution as a function of composition x. We also predicted the phase separation of the two partially miscible components and calculated the enthalpy ∆H using the interaction parameter Ω. We observe an asymmetry about x = 0.46 in the phase diagram due to the x-dependant interaction parameter Ω = 12.69 − 1.32x kcal/mole. The equilibrium solubility limit, known as the miscibility gap is found to be around 3033 K.