Electronic and optical properties of plutonium metal and oxides from Reflection Electron Energy Loss Spectroscopy

DFT + U Study of Uranium Dioxide and Plutonium Dioxide with Occupation Matrix Control

“…Similar to UO 2 , PuO 2 bulk remains face-centered cubic after optimization and the optimized lattice parameter increases with the U value ( Figure 6 c), with 4.0 eV ≤ U ≤ 5.0 eV giving values close to experiments for AFM and NM. 34 , 43 − 46 These states have similar lattice parameters for a given U , while a much larger lattice parameter is predicted for FM PuO 2 with the same U value. This is by contrast to UO 2 , where although the largest lattice parameter was also obtained for the FM state, it is close to the AFM and NM lattice parameters for a given U value ( Figure 4 a).…”

“… As a function of U , the (a) energies of AFM, FM, and NM PuO 2 , (b) energy difference between AFM and NM PuO 2 ( E NM – E AFM ), (c) lattice parameter of AFM, FM, and NM PuO 2 , experimental values from refs ( 34 , 43 , 46 ), and (d) band gap of AFM, FM, and NM PuO 2 , experimental values from refs ( 38 , 47 ). Inset to panel (d) shows the band gap of NM PuO 2 calculated with U = 5–11 eV.…”

Quantitative XPS of plutonium: Evaluation of the Pu4f peak shape, relative sensitivity factors and estimated detection limits

“…The Pu6p 3/2 peak was fit using two peaks constrained to having equal FWHM, as well as the two peaks representing Pu 2 O 3 (O2s + Pu6p 3/2 ), and this afforded an oxide quantity of 11.6%. This approach suffers from having the Pu6p 3/2 oxide peak position and intensity ratio with the O2s constrained which may be incorrect as other reported spectra of Pu 2 O 3 show different intensities for these two peaks 40,49 . The IMFP for the Pu6p 3/2 core level makes this the most representative of the bulk material.…”

“…This negative intensity is indicative of a slightly larger FWHM in the δ-Pu (Ga) sample which has never been reported before. In developing a curve fit model to quantify the Pu4f satellite intensity, the first step was to obtain ideal parameters for the Pu4f spectrum of Pu 2 O 3 shown in Figure 2 which included the shake-up satellite of the Pu6p 3/2 transition 12,49 and applying constraints to the spin-orbit splitting, area ratio and FWHM. The curve fit model for Pu 2 O 3 was then included in fitting both the spectra of α-Pu and δ-Pu(Ga) with two asymmetric lines to represent spin-orbit doublet of the metal or alloy typical of actinide metals.…”

“…This approach suffers from having the Pu6p 3/2 oxide peak position and intensity ratio with the O2s constrained which may be incorrect as other reported spectra of Pu 2 O 3 show different intensities for these two peaks. 40,49 The IMFP for the Pu6p 3/2 core level makes this the most representative of the bulk material. Currently, it is also not clear how the Pu6p 3/2 two-peak structure will change with alloying, also noting that the Ga3d peak overlaps with this transition, and until this is known, it is likely to exclude the use of this core level for quantification.…”