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Sans Measurements of Deuterium Trapped at Grain Boundaries in Palladium
Published online by Cambridge University Press: 21 February 2011
Abstract
Small-angle neutron scattering from grain boundary interfaces has been investigated in polycrystal palladium with and without deuterium dissolved in the solution phase. Polycrystalline samples were prepared using two different procedures: (1) single crystal material was recrystallized at 517°C after 78% cold working, and (2) an extruded polycrystal rod was investigated as received, or recrystallized at 600°C and 680°C. The expected 1/Q2 scattering profile (where Q is the neutron wavevector transfer) from grain boundaries has been observed, and the absolute cross sections permit a determination of the grain boundary surface concentration of missing palladium atoms and of trapped deuterium. The vacancy and trapped deuterium surface concentration determined in these measurements was 0.2-0.3 vacancies/Å2 and 0.4-0.6 deuterons/Å2, respectively. The measurements were extended to the low Q region (Q ≥0.006 1/Å) where the scattering response was dominated by Porod 1/Q4 behavior typical of internal voids. This behavior was especially strong for the samples fabricated from the extruded polycrystal, but was also present in the as-received single crystal. The degradation of the single crystal Porod response after compressional cold working is in reasonable agreement with the calculated effect of flattening a spherical void.
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- Copyright © Materials Research Society 1994
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