In situ EELS observation of graphite structure modification due to hydrogen ion irradiation

Dynamic microstructural evolution of graphite under displacing irradiation

“…To date, however, the majority of work on microstructural radiation damage in graphite has been confined to ex situ analysis of neutron (for examples see [31][32][33][34][35]) and ion (for examples see [36][37][38][39][40]) irradiated material with only a small number of studies using TEM with in situ ion [41][42][43][44][45] and electron [15,[46][47][48] irradiation. Radiation damage is a complex dynamic process in which multiple mechanisms compete to determine the ultimate outcome.…”

In Situ EELS and TEM Observation of Boron Carbide (B4C) During Hydrogen- and Helium-Ion Bombardments

“…simultaneously with HI and He+ ion showed small but observable bubbles, the phenomenon of which can be expected from reference data on helium-ion bombarded B4C [7]. In the case of graphite [8,11], bubbles are also more easily formed by helium-ion bombardments rather than hydrogen-ion bombardments. It is reported [12] During the C -A transition of B4C due to the hydrogen-ion bombardments, plasmon-loss peak of an EELS profile shifted to lower energy side as shown in Figure 2.…”

“…This 7r* peak generally indicates the existence of sp2 bonding, i.e., C = C double bonding in the material. This 7r* peak have been observed even for amorphous graphite transformed by ion-bombardments, not only for crystalline graphite, indicating the existence of sp2 carbon atoms, or C = C double bonding [8] in the amorphous carbon. Because the 7r* peak appeared both for B4C bombarded with single (H+2) ion species and with double ( H2 and He+) ion species, as seen in Figure 6 and Figure 7, it is reasonable to think that the C = C double bonding has been produced by the displacements and rearrangement of constituent carbon atoms.…”

“…Generally, the decrease of plasmon-loss peak energy implies the decrease of free-or valence-electron density in the material. In this case, the change of plasmon-loss peak energy is correspondent on the C -A transition of B4C, as in the case of ion-bombarded graphite [8]. Figure 3 shows the relationship between hydrogen-ion fluence and plasmon-loss energy.…”

“…Previously, we have carried out EELS studies on ion-bombarded graphite and diamond [8][9][10], in which EELS technique was found highly valid to study the change of chemical structure of the ion-bombarded materials. This paper reports the results of in situ EELS and TEM observations of B4C during hydrogenand helium-ion bombardments.…”