Article (Scientific journals)
Lattice dynamics in intermetallic Mg2Ge and Mg2Si
Bessas, D.; Simon, R. E.; Friese, K. et al.
2014In Journal of Physics: Condensed Matter, 26 (48)
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Keywords :
Crystal lattices; Dynamics; Germanium; Isomers; Lattice vibrations; Silicon; Thermal expansion; Inelastic neutrons; Macroscopic measurements; Partial densities; Theoretical calculations; Thermoelectrics; Vibrational state; Volume thermal expansions; Magnesium
Abstract :
[en] The lattice dynamics of polycrystalline Mg2Ge and Mg2Si are compared using both microscopic and macroscopic measurements as well as theoretical calculations. The volume thermal expansion coefficient between 200 and 300K was found to be 4.37(5)•10-5K-1 in Mg2Ge, compared to 3.69(5)•10-5K-1 in Mg2Si. Inelastic neutron scattering measurements yield densities of phonon states which are in line with theoretical calculations. The microscopic data were corroborated with macroscopic calorimetry measurements and provide quantified values for anharmonicity. The estimated macroscopic Grneisen parameter is, γMg 2Si=1.17(5) and γMg 2Ge=1.46(5) at 295K, in excellent agreement with Raman scattering data. Although the element specific mean force constants are practically the same, in Mg2Ge and Mg2Si, a mass homology relation alone cannot reproduce the difference in the partial densities of vibrational states in these compounds and differences in elemental bonding should be taken into account. © 2014 IOP Publishing Ltd.
Disciplines :
Physics
Author, co-author :
Bessas, D.;  Jülich Centre for Neutron Science JCNS, Peter Grünberg Institut PGI, Forschungszentrum Jülich GmbH, Jülich, Germany, Faculté des Sciences, Université de Liège, Liège, Belgium, European Synchrotron Radiation Facility, Grenoble, France
Simon, R. E.;  Jülich Centre for Neutron Science JCNS, Peter Grünberg Institut PGI, Forschungszentrum Jülich GmbH, Jülich, Germany, Faculté des Sciences, Université de Liège, Liège, Belgium
Friese, K.;  Jülich Centre for Neutron Science JCNS, Peter Grünberg Institut PGI, Forschungszentrum Jülich GmbH, Jülich, Germany
Koza, M.;  Institut Laue Langevin, 6 rue Jules Horowitz, Grenoble Cedex 9, France
Hermann, Raphaël ;  Université de Liège > Département de chimie (sciences) > Département de chimie (sciences)
Language :
English
Title :
Lattice dynamics in intermetallic Mg2Ge and Mg2Si
Publication date :
2014
Journal title :
Journal of Physics: Condensed Matter
ISSN :
0953-8984
eISSN :
1361-648X
Publisher :
Institute of Physics Publishing
Volume :
26
Issue :
48
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 02 June 2015

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