Heavy-ion bombardment of a glass surface is a conventional laboratory
technique for producing damage of interest for radioactive waste
encapsulation. At energy of order 100 keV such a bombardment simulates the
damage produced by α-recoil nuclei and fission fragments resulting from the
nuclear decay. The damage region is 100–500 nm depending on conditions of
the bombardment.
In the present work some results of EPR study of point defects formed in
silicate, borate, borosilicate, phosphate and other oxide glasses irradiated
with different charge particles (C, N, O, Ar. Mn, Cu, Pb) at energy E=150
keV and large total fluence of ions (up to 1017 cm-2)
are reported. Electron paramagnetic resonance (EPR) is a very sensitive
technique which gives an information on the structure of point defects and
their content. It is shown that in some cases (for example, in borate
glasses) the oxygen hole centers similar to ones observed in γ-irradiated
glasses are formed after ion bombardment. However, in the majority of cases
new defects which are not typical of γ-irradiated oxide glasses were found
They were large molecular oxygen ions (O2-O3-O4-) located in the cavities formed under ion bombardment in the
near surface layer of glass. It should be noted that the relative content of
these defects is of the order of several tens per 1000 incident ions. This
content decreases with increasing fluence and atomic mass of incident ions.
It indicates indirectly that point defects are clustered when the damage of
the near surface layer becomes strong. The formation of gaseous oxygen is
possible in cavities of the damage surface layer.
It was found that some elements (for example C, N and transition metals)
form chemical compounds with oxygen. The migration of alkali ions promotes
the formation of such compounds since the chemical compounds were detected
by means EPR in glasses rich in alkali oxides.