Alpha-plutonium's polycrystalline elastic moduli over its full temperature range

α -plutonium's volume-corrected polycrystal elastic moduli were measured between 18 K and the upper limit of its occurrence, near 400 K . The two independent moduli for a polycrystal-bulk and shear-behave smoothly, indicating no phase transition. Both moduli show the same 50% increase on coolin...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2007-10, Vol.122 (4), p.1994-2001
Main Authors: Migliori, A., Pantea, C., Ledbetter, H., Stroe, I., Betts, J. B., Mitchell, J. N., Ramos, M., Freibert, F., Dooley, D., Harrington, S., Mielke, C. H.
Format: Article
Language:English
Subjects:
Exact sciences and technology
Fundamental areas of phenomenology (including applications)
Physics
Solid mechanics
Static elasticity (thermoelasticity...)
Structural and continuum mechanics
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Summary:α -plutonium's volume-corrected polycrystal elastic moduli were measured between 18 K and the upper limit of its occurrence, near 400 K . The two independent moduli for a polycrystal-bulk and shear-behave smoothly, indicating no phase transition. Both moduli show the same 50% increase on cooling, an order of magnitude larger than in other metals. The Debye temperature obtained from low-temperature elastic moduli, 207 K , significantly exceeds most previous estimates. The Gruneisen parameter γ = 5.3 , obtained from the temperature dependence of the bulk modulus, is intermediate among previous estimates using other approaches, α -plutonium's Poisson ratio ν is low: 0.18, nearly temperature independent, and its small decrease on warming opposes usual behavior. The high γ , large but equal bulk modulus and shear modulus fractional stiffening on cooling, and near-temperature-invariant ν are attributed to a single mechanism: 5 - f electron localization-delocalization.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.2767419