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Low-temperature instability in [sup 242]Pu[sub 0.98]Ga[sub 0.02] [electronic resource].

Published:
Washington, D.C. : United States. Dept. of Energy, 2001.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description:
5 pages : digital, PDF file
Additional Creators:
Los Alamos National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary:
We have made an unsuccessful attempt to make a detailed characterization by neutron powder diffraction of the δ-α' transformation that is known to occur at low temperatures in dilute Pu-Ga alloys. The α'-structure is a variant of the monoclinic a α'-phase, except that the lattice constants are a bit different, with some (or all) of the Pu sites partially occupied by Ga. This transformation is easily detected by dilatometric methods because of the 19% volume difference between the δ and α'-phases. In our study, we used 242Pu in a Pu0.98Ga0.02 alloy to minimize neutron absorption and cooled the sample very slowly to maximize the degree of transformation. We did not detect any transformation to the α'-phase, but instead observed a slight line broadening effect that was visible in the raw data. The onset temperature of the line broadening (150K) coincides with observations of the δ-α' transformation. We have developed two alternative explanations for the line broadening effect: (1) the occurrence at low temperatures of a cubic-tetragonal transformation in Ga-stabilized alloy or (2) the occurrence at low-temperature of a spontaneous anisotropic microstrain that is supported by the highly anisotropic elastic constants of δ-Pu.
Report Numbers:
E 1.99:la-ur-01-5833
la-ur-01-5833
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Note:
Published through SciTech Connect.
01/01/2001.
"la-ur-01-5833"
Submitted to: International Conference Actinides 2001/Journal of Nuclear Science and Technology, Nov. 4-9, 2001, Hayama, Japan.
Lawson, A. C.; Martinez, B. S.; Roberts, J. A.; von Dreele, R. B.
View MARC record | catkey: 14710909