Radiation-induced modifications in copper oxide growth
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Radiation‑induced modifications in copper oxide growth Jessica L. Bishop1,4 · Will F. Cureton1 · Miguel L. Crespillo2 · Michael Koehler3 · John D. Auxier II1,4 · Maik Lang1 Received: 7 July 2020 / Accepted: 4 November 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Cu samples were irradiated with 10 MeV Au3+ ions at 200 °C to damage levels of 5, 10, and 15 displacements per atom (dpa) as an analogue to study long term self-irradiation effects of alpha-decay in Pu. Samples were then subject to accelerated aging at 350 °C for 1 h in air resulting in mixed oxide layer growth ( Cu2O and CuO). Raman spectroscopy revealed that the CuO phase fraction was gradually decreased as the damage level increased. These findings indicate that accumulated damage from self-irradiation causes quantifiable modifications in metal oxidation that could serve as a novel forensic signature. Keywords Radiation damage · Oxidation · Copper · Raman spectroscopy · Nuclear forensics
Introduction The control of special nuclear material (SMN) and strategic special nuclear material (SSNM), namely Pu, is crucial to national security due to its utilization in nuclear explosives [1, 2]. Plutonium has a complex phase diagram with many different structure types that form over a range of temperatures; of interest for the nuclear forensic community is deltaphase Pu, which is stable from 310 to 452 °C for pure Pu and can be stabilized at room temperature with addition of ~ 0.3% Ga. It is of supreme importance that these materials be monitored, studied, and documented for (i) facility accountability and (ii) nuclear forensics and recovery in the event of their diversion from a nuclear facility. Both physical and chemical properties of SNM/SSNM evolve over time due to the decay and transmutation of radionuclides as well as the accumulated damage from self-irradiation [3–5]. These changes occur gradually with time and can be correlated with the age of the material for forensic purposes. For * Maik Lang [email protected] 1
Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996, USA
2
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
3
Joint Institute for Advance Materials Diffraction Facility, University of Tennessee, Knoxville, TN 37996, USA
4
Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
example, radiochronometry utilizes mass spectroscopy to determine the changes in chemical compositions and ratio of radioisotopes as a measure of the time that has passed since material fabrication [6]. Decay counting techniques based on alpha or gamma emission are in some cases employed to identify specific radionuclides that have formed in a given material [7, 8]. Many analytical techniques are currently used for SNM/ SSNM with each having some limitations, such as being destructive, requiring large sample quantities (> 20 g), or being only applicable to certain radionuclides [9]. Nuclear resonance fluorescence (NRF) techniques have been rec
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