Calculation of the Unstable Mixing Region in $Zn_{1-x}Cd_xO$ Ternary Alloys

The $Zn_{1-x}Cd_xO$ ternary alloys with a narrow band gap, which are useful for light emitters in the visible wavelengths, are studied with respect to the unsteady region in mixing. This unstable region in mixing is calculated from the free energy of mixing using the strictly regular solution model. The interaction parameter used in this calculation is obtained by means of the valence-force-field model. An influence of the strain energy induced by substrate on the region of the spinodal decomposition for the $Zn_{1-x}Cd_xO$ system is studied and discussed.