The frequencies of the normal modes of vibration of FePd single crystal were measured using inelastic neutron scattering. The measurements were performed for the L10 ordered structure at 300 and 860K and for the face-centered cubic disordered state at 1020K. A general lowering of phonon frequencies with increasing temperature was found in FePd, the dependence being the strongest for acoustical transverse [ξξξ] branches. The migration energies as well as several thermodynamic quantities were calculated from the densities of states. The contribution of ordering to the migration energy, as experimentally determined here, agreed well with that obtained by Monte Carlo simulations in the L10 structure.

Inelastic Neutron Scattering and Migration Energies in FePd. T.Mehaddene, M.Zemirli, V.Pierron-Bohnes, M.C.Cadeville, B.Hennion, A.Marty, I.Schuster, K.Tanaka, H.Numakura: Catalysis Today, 2004, 89[3], 313-8