title: Alpha-plutonium's polycrystalline elastic moduli over its full temperature range.
abstract: alpha-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 gamma=5.3, obtained from the temperature dependence of the bulk modulus, is intermediate among previous estimates using other approaches, alpha-plutonium's Poisson ratio nu is low: 0.18, nearly temperature independent, and its small decrease on warming opposes usual behavior. The high gamma, large but equal bulk modulus and shear modulus fractional stiffening on cooling, and near-temperature-invariant nu are attributed to a single mechanism: 5-f electron localization-delocalization.
authors: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. migliori@cybermesa.com
authors: A
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authors: Migliori
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authors: Pantea
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authors: Ledbetter
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authors: Stroe
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authors: Betts
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authors: Mitchell
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authors: Ramos
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authors: Freibert
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authors: Dooley
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authors: Harrington
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authors: Mielke