where j is the chemical species with fractional occupation, and y j is the fraction of the disordered sites occupied by j. The fractions y j should add up to 1 i.e., Â j y j = 1. The vibrational entropy change is assumed to be zero due to the approximate cancellation of the vibrational entropy between the alloy and the parent compounds. A typical synthesis temperature of 823 K is used to compute DG mix in Figure . The trends remain unchanged at higher synthesis temperatures.