McQueeney, R. J. and Lawson, A. C. and Migliori, A. and Kelley, T. M. and Fultz, B. and Ramos, M. and Martinez, B. and Lashley, J. C. and Vogel, S. C. (2004) Unusual phonon softening in delta-phase plutonium. Physical Review Letters, 92 (14). Art. No. 146401. ISSN 0031-9007 http://resolver.caltech.edu/CaltechAUTHORS:MCQprl04
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The phonon density of states and adiabatic sound velocities were measured on fcc-stabilized (242)pu(0.95)Al(0.05). The phonon frequencies and sound velocities decrease considerably (soften) with increasing temperature despite negligible thermal expansion. The frequency softening of the transverse branch along the  direction is anomalously large (similar to 30%) and is very sensitive to alloy composition. The large magnitude of the phonon softening is not observed in any other fcc metals and may arise from an unusual temperature dependence of the electronic structure in this narrow 5f-band metal.
|Additional Information:||©2004 The American Physical Society. Received 11 June 2003; published 7 April 2004. R. J. M. thanks M. Graf, B. Harmon, M. Manley, J. Sarrao, J. Schmalian, S. Shastry, J. L. Smith, C. Stassis, J. D. Thompson, and J. Wills for valuable discussions. This research is sponsored by the United States Department of Energy National Nuclear Security Administration and by the Office of Science DE-FG03-96ER45572. The work has benefited from the use of the Los Alamos Neutron Science Center at Los Alamos National Laboratory. LANSCE is funded by the U.S. Department of Energy under Contract No.W-7405-ENG-36.|
|Subject Keywords:||plutonium; plutonium alloys; aluminium alloys; soft modes; phonon spectra; neutron diffraction; acoustic wave velocity|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||12 Jun 2006|
|Last Modified:||26 Dec 2012 08:54|
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