Isochronal annealing effects on local structure, crystalline fraction, and undamaged region size of radiation damage in Ga-stabilized δ-Pu

Abstract

The effects on the local structure due to self-irradiation damage of Ga stabilized δ-Pu stored at cryogenic temperatures have been examined using extended x-ray absorption fine structure (EXAFS) experiments. Extensive damage, seen as a loss of local order, was evident after 72 days of storage below 15 K. The effect was observed from both the Pu and Ga sites, although less pronounced around Ga. Isochronal annealing was performed on this sample to study the annealing processes that occur between cryogenic and room temperature storage conditions, where damage is mostly reversed. Damage fractions at various points along the annealing curve have been determined using an amplitude-ratio method, standard EXAFS fitting, and a spherical crystallite model, and provide information complementary to previous electrical resistivity-and susceptibility-based isochronal annealing studies. The use of a spherical crystallite model accounts for the changes in EXAFS spectra using just two parameters, namely, the crystalline fraction and the particle radius. Together, these results are discussed in terms of changes to the local structure around Ga and Pu throughout the annealing process and highlight the unusual role of Ga in the behavior of the lowest temperature anneals.

Towards quantitative inference of nanoscale defects in irradiated metals and alloys

“…2(c). EXAFS has been used to study the impact of self-irradiation in Pu and its alloys as a function of dose [71][72][73][74]. Booth et al use EXAFS to determine the fraction of a sample that is damaged and compare these measurements to estimates based on point defect production and annealing [72].…”

Towards Quantitative Inference of Nanoscale Defects in Irradiated Metals and Alloys

“…This enables experiments to be directly compared to simulations, as demonstrated by Andrianov et al (Andrianov et al, 2021) in Figure 2C. EXAFS has been used to study the impact of self-irradiation in Pu and its alloys as a function of dose (Booth et al, 2007;Booth et al, 2013;Olive et al, 2016;Booth and Olive, 2017). Booth et al use EXAFS to determine the fraction of a sample that is damaged and compare these measurements to estimates based on point defect production and annealing (Booth et al, 2013).…”

Effect of temperature and radiation damage on the local atomic structure of metallic plutonium and related compounds

“…Most recently, Olive et al [93] performed isochronal annealing EXAFS measurements on the same δ-Pu sample measured in Ref. [86], and introduced an analysis of particle size based on a method used in nanoparticles [94,95].…”