Structural Relationship between Negative Thermal Expansion and Quartic Anharmonicity of Cubic ScF_3
Abstract
Cubic scandium trifluoride (ScF_3) has a large negative thermal expansion over a wide range of temperatures. Inelastic neutron scattering experiments were performed to study the temperature dependence of the lattice dynamics of ScF3 from 7 to 750 K. The measured phonon densities of states show a large anharmonic contribution with a thermal stiffening of modes around 25 meV. Phonon calculations with first-principles methods identified the individual modes in the densities of states, and frozen phonon calculations showed that some of the modes with motions of F atoms transverse to their bond direction behave as quantum quartic oscillators. The quartic potential originates from harmonic interatomic forces in the DO_9 structure of ScF_3, and accounts for phonon stiffening with the temperature and a significant part of the negative thermal expansion.
Additional Information
© 2011 American Physical Society. Received 16 March 2011; published 4 November 2011. The authors thank A. P. Wilkinson for important discussions. This work was supported by DOE BES under Contract No. DE-FG02-03ER46055. The work benefited from software developed in the DANSE project under NSF Grant No. DMR-0520547. Research at Oak Ridge National Laboratory's SNS was sponsored by the Scientific User Facilities Division, BES, DOE.Attached Files
Published - Li2011p16450Phys_Rev_Lett.pdf
Supplemental Material - EPAPS.pdf
Supplemental Material - MD-300k.mpg
Supplemental Material - README.TXT
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Additional details
- Eprint ID
- 28424
- Resolver ID
- CaltechAUTHORS:20111212-121400317
- DE-FG02-03ER46055
- Department of Energy (DOE)
- DMR-0520547
- NSF
- Created
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2011-12-22Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field