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Lattice dynamics and elasticity in thermoelectric Mg2Si1-xSnx

Kolbes, Benedikt and de Boor, Johannes and Alatas, Ahmet and Hu, Michael Y. and Simon, Ronnie E. and Hermann, Raphaël P. (2019) Lattice dynamics and elasticity in thermoelectric Mg2Si1-xSnx. Physical Review Materials. American Physical Society. DOI: 10.1103/PhysRevMaterials.3.025404 ISSN 2475-9953

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Abstract

Lattice dynamics and elastic constants in Mg2Si1−xSnx were investigated using resonant ultrasound spectroscopy, Mössbauer spectroscopy, nuclear inelastic scattering, and inelastic x-ray scattering. Increasing the Sn content x results in smaller elastic constants, lower Sn specific Debye temperature, lower speed of sound, and a softening of acoustic Sn specific phonons. However, close to band convergence at about x=0.6, the shear modulus is well below the expected value, which suggests a pronounced connection between band convergence and lattice dynamics in this system. Based on the determined speed of sound and average phonon group velocity, the importance of optical phonons for lattice thermal conductivity is discussed, as the significant reduction in both velocities would yield an implausibly low lattice thermal conductivity of only about 60% of the experimental value. Sn specific thermodynamic quantities calculated from the Sn specific density of phonon states substantiate the general softening of lattice vibrations upon substitution of Si by Sn. A major contribution to the vibrational entropy is thus due to Sn specific vibrational modes. The generalized density of phonon states in Mg2Si1−xSnx derived from inelastic x-ray scattering for one composition shows that vibrational modes related to lightweight Mg and Si set in above 12.5 meV, whereas Sn specific modes are concentrated around 11 meV.

Item URL in elib:https://elib.dlr.de/130584/
Document Type:Article
Title:Lattice dynamics and elasticity in thermoelectric Mg2Si1-xSnx
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Kolbes, BenediktUniversity of Applied Sciences Bremerhaven, An der Karlstadt 8, 27568 Bremerhaven, Germany and Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, GermanyUNSPECIFIED
de Boor, JohannesGerman aerospace center, institute of materials research, köln, germanyhttps://orcid.org/0000-0002-1868-3167
Alatas, AhmetAdvanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USAUNSPECIFIED
Hu, Michael Y.Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USAUNSPECIFIED
Simon, Ronnie E.Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, GermanyUNSPECIFIED
Hermann, Raphaël P.Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USAUNSPECIFIED
Date:28 February 2019
Journal or Publication Title:Physical Review Materials
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1103/PhysRevMaterials.3.025404
Publisher:American Physical Society
ISSN:2475-9953
Status:Published
Keywords:Lattice Dynamics; elasticity; thermoelectric; Mg2Si1−xSnx
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Technik für Raumfahrtsysteme
DLR - Research theme (Project):R - Systemtechnologien
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Thermoelectric Materials and Systems
Deposited By: Yasseri, Mohammad
Deposited On:14 Nov 2019 17:45
Last Modified:28 Feb 2020 03:00

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