Calculation of Excess Free Energy of Mixing and Analysis of Phonon Spectra With Clustering Parameter in III—V Pseudobinary Alloys

Publisher Website
Google Scholar
Abstract
The excess free energy of mixing, ΔGex, is calculated and the phonon spectra for III—V pseudobinary alloys A1–xBxC are analyzed on the basis of a cluster model. ΔGex is a function of the clustering parameter β which represents the deviation from the random atomic distribution. The value of β giving the minimum excess free energy, βs, takes the maximum value at x = 0.5 and it increases with increase in the relative difference of lattice constants, \documentclass{article}\pagestyle{empty}$ \Delta a\sqrt a $ . The value of β giving the best agreement between the measured phonon frequencies and the calculated ones, βph, takes the maximum value also at about x = 0.5 in systems exhibiting the phonon spectra of partly‐two mode type. The value of βs at x = 0.5 and βph over the entire composition range is zero for two‐mode systems, such as (AlGa)—V.