Vibrational properties of a 2D Ising alloy Original Research Article

The effects of short-range order on phonons in pseudobinary solid solutions AxB1−xC were studied for the first time by means of the direct diagonalization of a dynamical matrix corresponding to the equilibrial distribution of impurity atoms. For two-mode alloys it is shown that ordering in the sublattice with impurity produces extra modes of the spectral density of phonon states while clustering mainly shifts the fundamental modes upwards in frequency. We also show that in some cases clustering may affect the (one/two-mode) type of optical spectra. We compare qualitatively our results to available experimental data for semiconducting mixed crystals.