Vibrational behavior of the Mn+1AXn phases from first-order Raman scattering (M=Ti,V,Cr, A=Si, X=C,N)

We report on the Raman spectra of Ti3SiC2 (312), M2AlC (211) (M=Ti, V, Cr, and Nb) and Ti4AlN3 (413), as representative compounds from the family of M(n+1)AX(n) phases. Intense and narrow first-order Raman peaks are observed, and we present an analysis of the spectra based on symmetry considerations and from results of first-principles calculations of phonon frequencies. The agreement between experimental and calculated mode energies is excellent. The identification of the modes enables application of Raman scattering as a diagnostic tool for the detailed study of the structural and physical properties of this family of compounds and their engineered solid solutions.