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Vibrational modes in nanocrystalline iron under high pressure

Papandrew, Alexander B. and Yue, Alan F. and Fultz, Brent and Halevy, Itzhak and Sturhahn, Wolfgang and Toellner, Thomas S. and Alp, E. Ercan and Mao, Ho-kwang (2004) Vibrational modes in nanocrystalline iron under high pressure. Physical Review B, 69 (14). Art. No. 144301. ISSN 1098-0121. http://resolver.caltech.edu/CaltechAUTHORS:PAPprb04

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Abstract

The phonon density of states (DOS) of nanocrystalline 57Fe was measured using nuclear resonant inelastic x-ray scattering (NRIXS) at pressures up to 28 GPa in a diamond anvil cell. The nanocrystalline material exhibited an enhancement in its DOS at low energies by a factor of 2.2. This enhancement persisted throughout the entire pressure range, although it was reduced to about 1.7 after decompression. The low-energy regions of the spectra were fitted to the function AEn, giving values of n close to 2 for both the bulk control sample and the nanocrystalline material, indicative of nearly three-dimensional vibrational dynamics. At higher energies, the van Hove singularities observed in both samples were coincident in energy and remained so at all pressures, indicating that the forces conjugate to the normal coordinates of the nanocrystalline materials are similar to the interatomic potentials of bulk crystals.


Item Type:Article
Additional Information:©2004 The American Physical Society. Received 7 November 2003; published 12 April 2004. This work was supported by the U.S. National Science Foundation under Grant No. DMR-0204920. Use of the Advanced Photon Source is supported by the U.S. Department of Energy under Contract No. W-31-109-ENG-38.
Subject Keywords:iron; nanostructured materials; phonons; X-ray scattering; potential energy functions; high-pressure effects
Record Number:CaltechAUTHORS:PAPprb04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:PAPprb04
Alternative URL:http://dx.doi.org/10.1103/PhysRevB.69.144301
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3297
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:26 May 2006
Last Modified:26 Dec 2012 08:53

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