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Development of Elastic Recoil Detection Technique for Quantifying Light Isotope Concentrations in Irradiated TPBAR Materials

Doyle, Barney L.; Taylor, Caitlin A.; Hattar, Khalid M.; Muntifering, Brittany R.

The National Nuclear Security Administration's Tritium Sustainment Program is responsible for the design, development, demonstration, testing, analysis, and characterization of tritium-producing burnable absorber rods (TPBARs) and their components, in addition to producing tritium for the nation's strategic stockpile. The FY18 call for proposals included the specific basic science research topic, "Demonstration and evaluation of advanced characterization methods, particularly for quantifying the concentration of light isotopes (1H, 2H, and 4He, 6Li, and 7Li) in metal or ceramic matrices". A project IWO-389859 was awarded to the Ion Beam Lab (IBL) at Sandia-NM in FY18. This reports the success we had in developing and demonstrating such a method: 42 MeV Si+ 7 from the IBL' s Tandem was used to recoil these light isotopes into special detectors that separated all these isotopes by simultaneously measuring the energy and stopping power of these reoils. This technique, called Heavy Ion - Elastic Recoil Detection or HI-ERD, accurately measured the enriched 6 Li/Li-total of 0.246 +- 0.016, compared to the known value of 0.239. The isotopes 1H, 2H, 4He, 6Li and 7Li were also measured. (page intentionally left blank)

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TYPE SAND Report YEAR 2018
OSTIDOI

Impact of oleylamine: oleic acid ratio on the morphology of yttria nanomaterials

Journal of Materials Science

Treadwell, LaRico J.; Boyle, Timothy J.; Bell, Nelson S.; Rodriguez, Mark A.; Muntifering, Brittany R.; Hattar, Khalid M.

The impact on the final morphology of yttria (Y2O3) nanoparticles from different ratios (100/0, 90/10, 65/35, and 50/50) of oleylamine (ON) and oleic acid (OA) via a solution precipitation route has been determined. In all instances, powder X-ray diffraction indicated that the cubic Y2O3 phase (PDF #00-025-1200) with the space group I-3a (206) had been formed. Analysis of the collected FTIR data revealed the presence of stretches and bends consistent with ON and OA, for all ratios investigated, except the 100/0. Transmission electron microscopy images revealed regular and elongated hexagons were produced for the ON (100/0) sample. As OA was added, the nanoparticle morphology changed to lamellar pillars (90/10), then irregular particles (65/35), and finally plates (50/50). The formation of the hexagonal-shaped nanoparticles was determined to be due to the preferential adsorption of ON onto the {101} planes. As OA was added to the reaction mixture, it was found that the {111} planes were preferentially coated, replacing ON from the surface, resulting in the various morphologies noted. The roles of the ratio of ON/OA in the synthesis of the nanocrystals were elucidated in the formation of the various Y2O3 morphologies, as well as a possible growth mechanism based on the experimental data.

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TYPE Journal Article YEAR 2017
ScopusOSTIDOI

In situ Transmission Electron Microscopy He+ implantation and thermal aging of nanocrystalline iron

Journal of Nuclear Materials

Muntifering, Brittany R.; Fang, Youwu; Leff, Asher C.; Dunn, Aaron; Qu, Jianmin; Taheri, Mitra L.; Dingreville, Remi P.; Hattar, Khalid M.

The high density of interfaces in nanostructured materials are hypothesized to improve radiation tolerance compared to coarse-grained materials. In order to investigate the roles of vacancies, self-interstitials, and helium, both room temperature in situ TEM He+ implantation and annealing, as well as high temperature He+ implantation was performed on nanocrystalline iron. Dislocation loops are formed by the accumulation of mobile point defects rather than by displacement cascades at intermediate temperatures. Around 600 °C, loops disappeared through gradual shrinking, which is hypothesized to correspond to the annihilation of self-interstitial atoms by mobile vacancies that also resulted in cavity formation. The room temperature implantation resulted in cavities evenly distributed throughout the grain after annealing, whereas cavities were predominately observed at grain boundaries for the elevated temperature implantation. This difference is associated with the formation of stable helium-vacancy complexes in the grains during room temperature implantation, which is not present during high temperature implantation.

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TYPE Journal Article YEAR 2016
ScopusOSTIDOI

Cavity evolution at grain boundaries as a function of radiation damage and thermal conditions in nanocrystalline nickel

Materials Research Letters

Muntifering, Brittany R.; Blair, Sarah J.; Gong, Cajer; Dunn, Aaron; Dingreville, Remi P.; Qu, Jianmin; Hattar, Khalid M.

Enhanced radiation tolerance of nanostructured metals is attributed to the high density of interfaces that can absorb radiationinduced defects. Here, cavity evolution mechanisms during cascade damage, helium implantation, and annealing of nanocrystalline nickel are characterized via in situ transmission electron microscopy (TEM). Films subjected to self-ion irradiation followed by helium implantation developed evenly distributed cavity structures, whereas films exposed in the reversed order developed cavities preferentially distributed along grain boundaries. Post-irradiation annealing and orientation mapping demonstrated uniform cavity growth in the nanocrystalline structure, and cavities spanning multiple grains. These mechanisms suggest limited ability to reduce swelling, despite the stability of the nanostructure.

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TYPE Journal Article YEAR 2016
ScopusOSTIDOI
32 Results
32 Results