Deuterium trapping at vacancy clusters in electron/neutron-irradiated tungsten studied by positron annihilation spectroscopy

Short positron lifetime at vacancies observed in electron-irradiated tungsten: Experiments and first-principles calculations

“…This value is comparable to that (193-200 ps) calculated for isolated monovacancies in W [7,8,9]. However, some experimental studies on irradiated W have reported a positron lifetime component of 169-175 ps [9,10,11], which is significantly shorter than that calculated for isolated monovacancies.…”

“…However, the vacancy-related positron lifetime of τ 2 = 171 ± 1 ps observed for the electron-irradiated sample at temperatures below 573 K is considerably shorter than the calculated values for isolated monovacancies. Table 2 shows the vacancy-related positron lifetimes reported in previous irradiation studies on W [4,5,6,9,10,11,13]. Some studies [9,10,11], including the present one, have reported vacancy-related positron lifetimes, which are significantly shorter than the value calculated for isolated monovacancies.…”

“…Table 2 shows the vacancy-related positron lifetimes reported in previous irradiation studies on W [4,5,6,9,10,11,13]. Some studies [9,10,11], including the present one, have reported vacancy-related positron lifetimes, which are significantly shorter than the value calculated for isolated monovacancies. Positron lifetime calculations for the V -X complexes summarized in Table 1 show that the decoration of a monovacancy with C, N, or O atom shortens the respective positron lifetimes to ∼170 ps.…”

Precipitation of supersaturated solute in H ion irradiated Fe-Au and Fe-Au-W alloys studied by positron annihilation spectroscopy

“…Hydrogen is an isotope of deuterium which only has valance electrons, no core electrons. Therefore, the momentum distribution as detected in CDB measurements will be different [54]. However, H + ions irradiated iron contains a large amount of H-V complexes, which will directly change the annihilation probability of the localized positrons with Fe electrons.…”

Recent advances in characterising irradiation damage in tungsten for fusion power

“…While TEM offers the great advantage of direct imaging of defects, it requires extensive and invasive sample preparation and cannot resolve defects smaller than 1.5 nm [63]. Another technique often adopted for examining vacancy type irradiation defects in crystalline materials like tungsten, is positron annihilation spectroscopy (PAS); for example to detect the annealing of radiation defects involving vacancy migration and evolution of vacancy dominated large defect clusters with changing temperature [64] or change in deuterium retention in tungsten due to deuterium trapping in vacancy-type defects [65] or to reliably estimate elementary point defects formed at cryogenic temperatures and their recovery kinetics as foundation for building predictive models on evolution of radiation damage [66]. However, interpretation of the PAS measurements requires supportive experimental methods or characterization techniques such as electron paramagnetic resonance (EPR).…”