Raman scattering by phonons of Ga1−xAlxSb mixed crystals

► The phonons of Ga1−xAlxSb mixed crystals are calculated by using supercells of 128 atoms. ► The Raman spectra of the crystals in question are calculated using the Bond Polarizability Model. ► The Bond Polarizabilities for the Ga (Al)-Sb bonds are estimated using certain relations. ► The two band behavior of Ga1−xAlxSb mixed crystals is reproduced. ► For small concentrations, the Al ions concentrate to neighboring cation planes.