Atomic Dynamics in Complex Metallic Alloys
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Atomic Dynamics in Complex Metallic Alloys Holger Euchner1,2,12, Stephane Pailhès3, Tsunetomo Yamada4 ,Ryuji Tamura4 ,Tsutomu Ishimasa5, Stephane Rols6, Helmut Schober6,7, Marek Mihalkovic8 ,Hans-Rainer Trebin1, Daniel Schopf1, Silke Paschen9, Amir Haghighirad10, Franz Ritter10, Wolf Assmus10, Yuri Grin11, Lien Nguyen9, Marc de Boissieu2 1
ITAP, Universität Stuttgart, Pfaffenwaldring 57/6 , 70550 Stuttgart, Germany
2
SIMAP, Grenoble-INP, CNRS, UJF, BP 75,38402 St Martin d’Hères Cedex, France
3
Université de Lyon1, CNRS, 69622 Villeurbanne, France
4
Department of Materials Science and Technology, Tokyo University, Noda 278-8510, Japan
5
Division of Applied Physics, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan 6
Institut Laue Langevin, BP 156, 38042 Grenoble, Cedex 9, France
7
Université Joseph Fourier, UFR de Physique, 38041 Grenoble Cedex 9, France
8
Institute of Physics, Slovak Academy of Sciences, 84228 Bratislava, Slovakia
9
Institute of Solid State Physics, TU Vienna, Wiedener Hauptstr. 8-10, 1040 Wien, Austria
10
Physikalisches Institut, Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany
11
MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany
12Institute
of Materials Science and Technology, TU Vienna, Karlsplatz 13, 1040 Wien, Austria
ABSTRACT Complex Metallic Alloys (CMAs) are metallic solids of high structural complexity, consisting of large numbers of atoms in their unit cells. Consequences of this structural complexity are manifold and give rise to a variety of exciting physical properties. The impact that such structural complexity may have on the lattice dynamics will be discussed. The surprising dynamical flexibility of Tsai-type clusters with the symmetry breaking central tetrahedron will be addressed for Zn6Sc, while in the Ba-Ge-Ni clathrate system the dynamics of encaged Ba guest atoms in the surrounding Ge-Ni host framework is analysed with respect to the experimentally evidenced strong reduction of lattice thermal conductivity. For both systems experimental results from neutron scattering are analyzed and interpreted on atomistic scale by means of ab initio and molecular dynamics simulations, resulting in a picture with the respective structural building blocks as the origin of the peculiarities in the dynamics. INTRODUCTION CMAs are intermetallic compounds that consist of large unit cells containing tens to thousands of atoms. Apart from large unit cell sizes, the cluster structure is a characteristic feature of many CMAs. There exist various complex phases that can be described in a rather simple way as periodic or quasiperiodic packings of atomic clusters. This intriguing cluster structure of CMAs is also the origin of different, competing length scales within these
compounds, as the unit cell dimensions can differ substantially from the dimensions of the cluster building blocks. Due to their structural peculiarities, many CMAs exhibit unusual properties, which make them interesting for appli
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