The u3si2-H system

Understanding xenon and vacancy behavior in UO2, UN and U3Si2: a comparative DFT+Ustudy

“…Not considering spin-orbit coupling (SOC) for UO 2 can yield reasonable lattice parameters and bulk moduli, [99][100][101][102] and the SOC effect is not considered in most of investigations of U 3 Si 2 [103][104][105] due to its negligible impact on its structural, mechanical and electronic properties. 51 For the defective UN system, although the formation energies of point defects with and without the consideration of SOC exhibit a significant decrease, energetic value comparisons show the same trend.…”

Structural and Phase Evolution in U3si2 During Steam Corrosion

“…x approaching 0) and still has highest (least favourable) formation energy at x = 0.25. Shivprasad et al [12] suggested that there are two stages of hydrogen absorption. We propose that this may be connected to H residing at different sites.…”

“…The unit cell volume increases almost linearly with hydrogen concentration, with ~3.3% volume expansion per formula unit x in U3Si2Hx. To the extent we can apply a linear relationship to recent experimental unit cell volume results [12], this suggests 4.3% volume expansion per H. This ratio is used below to estimate stoichiometry from lattice strain.…”

“…Mašková et al originally proposed the 8j site for H, but could not confirm this experimentally because the X-ray scattering cross section of H is negligible compared with those of U and Si. Middleburgh et al and Shivprasad et al calculated the solution energies of H at different crystallographic positions in a unit cell of U3Si2, for stoichiometry ranging U6Si4H1-4 [11,12]. They reinforced 8j site as the most favorable for H in this small, and therefore highly ordered, cell and without considering thermal and entropic effects.…”