Fultz, B. and Stephens, T. A. and Alp, E. E. and Hu, M. Y. and Sutter, J. P. and Toellner, T. S. and Sturhahn, W. (2000) Atom clusters and vibrational excitations in chemically-disordered Pt357Fe. Physical Review B, 61 (21). pp. 14517-14522. ISSN 0163-1829 http://resolver.caltech.edu/CaltechAUTHORS:FULprb00
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Inelastic nuclear resonant scattering spectra of Fe-57 atoms were measured on crystalline alloys of Pt3Fe-57 that were chemically disordered, partially ordered, and L1(2) ordered. Phonon partial density of states curves for Fe-57 were obtained from these spectra. Upon disordering, about 10% of the spectral intensity underwent a distinct shift from 25 to 19 meV. This change in optical modes accounted for most of the change of the vibrational entropy of disordering contributed by Fe atoms, which was (+0.10 +/- 0.03) k(B) (Fe atom)(-1). Prospects for parametrizing the vibrational entropy with low-order cluster variables were assessed. To calculate the difference in vibrational entropy of the disordered and ordered alloys, the clusters must be large enough to account for the abundances of several of the atom configurations of the first-nearest-neighbor shell about the Fe-57 atoms.
|Additional Information:||©2000 The American Physical Society. Received 12 November 1999. The work at Caltech was supported by the U.S. National Science Foundation under Contract No. DMR-9816617, and the work at Argonne was supported by the U.S. Department of Energy under Contract No. W-31-109-ENG-38.|
|Subject Keywords:||NUCLEAR RESONANT SCATTERING; FIRST-PRINCIPLES; ENTROPY; NI3AL; STATES; DIFFERENCE; DENSITIES; ALLOYS; ENERGY; FE-57|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||15 May 2006|
|Last Modified:||26 Dec 2012 08:52|
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