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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
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Localization of propagative phonons in a perfectly crystalline solid
S Pailhès1, H Euchner2, V M Giordano3
1Institute of Light and Matter, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
Physical Review Letters
|July 26, 2014
Summary
Intermetallic clathrates like Ba(8)Si(46) exhibit ultralow thermal conductivity. This study reveals how guest-atom interactions in these thermoelectric materials localize phonons, reducing heat transfer.
Area of Science:
- Solid-state physics
- Materials science
- Thermoelectrics
Background:
- Perfectly crystalline solids are typically excellent heat conductors.
- Intermetallic clathrates are guest-host materials with potential for thermoelectric applications due to their low thermal conductivity.
Purpose of the Study:
- Investigate the lattice dynamics of the binary intermetallic clathrate Ba(8)Si(46).
- Identify the mechanism responsible for the reduced lattice thermal conductivity in this perfect crystal structure.
Main Methods:
- Combined experimental and theoretical investigation.
- Analysis of lattice dynamics and phonon behavior.
Main Results:
- Identified a mechanism reducing lattice thermal conductivity intrinsic to the perfect crystal.
- Observed a drastic transfer of spectral weight to guest atoms above a critical wave vector.
- Demonstrated localization of propagative phonons due to harmonic guest-host interactions.
Conclusions:
- The guest-host interaction in Ba(8)Si(46) is key to its low thermal conductivity.
- Phonon localization driven by guest-atom dynamics explains the reduced heat transport in these thermoelectric materials.
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