First-order Raman scattering of the MAX phases: Ti2AlN, Ti2AlC0.5N0.5, Ti2AlC, (Ti0.5V0.5)2AlC, V2AlC, Ti3AlC2, and Ti3GeC2

Here, we report, for the first time, on the Raman spectra of Ti2AlN, Ti2AlC0.5N0.5, (Ti0.5V0.5)2AlC, Ti3AlC2, and Ti3GeC2 and compare the results with those of Ti2AlC and V2AlC reported previously. The first-order mode peaks of the end members are narrower than those of their respective solid-solution compounds. The Ti3AlC2 and Ti3GeC2 phases show, in addition to atomic displacements of the M and A atomic planes, modes that correspond with vibrations of the X sublattice relative to itself. We also predict the Raman modes using density functional theory. The agreement between theory and experiment was found to be satisfactory. Copyright (c) 2011 John Wiley & Sons, Ltd.