|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Hume-Rothery Award Symposium: Thermodynamics of Materials
||Temperature Dependent Phonon Anharmonicity in Elementary and Martensite Systems
||Winfried Petry, Michael Leitner, Pascal Neibecker, Jürgen Neuhaus
|On-Site Speaker (Planned)
The availability of accurate phonon dispersions for all temperatures up to the melting point is essential for the prediction of thermodynamic stabilities of crystal structures. Our measurements on a large range of systems demonstrate that the harmonic picture of non-interacting phonons does not adequately capture reality. Specifically, due to anharmonic interactions the phonon frequencies are renormalized and develop finite linewidths. Further, couplings to the electronic subsystem (including magnetic aspects) lead to characteristic phonon anomalies.
We will present temperature-dependent phonon dispersion relations on elementary systems with and without structural and magnetic phase transistions as well as on intermetallic shape-memory systems, in many cases up to the melting point. Recent examples are aluminum, iron in all its phases, and ferromagnetic Ni2MnZ systems. Niobium demonstrates a peculiar behaviour, showing a hardening of phonons with increasing temperature, which indicates a latent low-temperature instability towards a close-packed structure.
||Planned: A print-only volume