Phonon dispersion curves in Cr2AlC single-crystals

Abstract

Neutron inelastic scattering is used for the first time to measure phonon dispersion branches in Cr2AlC MAX phase single crystals with appreciable size. Phonon spectra are also calculated within the Density Functional Perturbation Theory (DFPT) framework and exhibit a very good match with experimental data, including high energy carbon-related optical branches. Both experiments and ab initio simulations confirm the existence of a substantial phonon gap and discard the presence of any softening mode or possible magnetic effect. IMPACT STATEMENT We synthesized Cr2AlC single-crystalline platelets with areas over 10 cm2. This breakthrough in materials synthesis was a prerequisite for measuring inelastic neutron scattering and phonon anisotropies.

Keywords

• MAX phases
• phonons
• neutron inelastic scattering
• nano-lamellar compounds