Full Recovery of Electron Damage in Glass at Ambient Temperatures

An unusually complete recovery of extensive electron-beam-induced damage in a thin film of a $\mathrm{CaO}\mathrm{\text{−}}{\mathrm{Al}}_2{\mathrm{O}}_3\mathrm{\text{−}}{\mathrm{SiO}}_2$ glass was discovered. Nanoscale measurements show that the Ca ions migrate about 10 nm away during irradiation and return during recovery. Oxygen atoms are trapped largely as molecular oxygen and do not migrate. Electron energy loss measurements demonstrate that the glass returns completely to the original compositional and structural state thus indicating that the glass is in a deep thermodynamic energy minimum.

Figure 1

ADF images of glass particle. (a) Before the damage, (b) after 2 min of electron-beam damage (only $6.3\times 6.3{\mathrm{nm}}^2$ area was damaged); (c)–(d) images recorded after 30 sec and 2 min of recovery with beam turned off; (e) line scans of the ADF intensities across damaged area [dashed line in (a)] obtained from images before and after damage [images (a) and (b)] and during recovery; (f) difference between line scans from (b) and (a).

Figure 2

(a) Evolution of the spectra of Ca $L_{2,3}$ edge and (b) O $K$ edge with continues damage. The bottom spectra in (a) and (b) were recorded after recovery, having beam off for 2 min. Spectrum of the O $K$ edge of ${\mathrm{O}}_2$ is reproduced from Ref. 16.

Figure 3

(a) Changes in integrated intensity of the Ca $L_{2,3}$ edge calculated using 346 to 354 eV energy range and the O $K$ edges, calculated using 525 to 555 eV energy range, with electron-beam exposure; (b) the ratio of the integrated intensity of the O $K$ edge in ${\mathrm{O}}_2$ to the total intensity of O $K$ edge. The decay of Ca $L_{2,3}$ edge is proportional to $\exp [-t/62]$, whereas the increase of the ratio $({\mathrm{O}}_2)/(\mathrm{\text{total}})$ is proportional to $\exp [-t/20]$.

Figure 4

(a) Measured EELS spectra of the Al and Si $L_{2,3}$ edges; (b) evolution of this spectra with continues damage and the recovery after 2 min. (c) Integrated intensity (from 74 to 90 eV energy range) of the Al $L_{2,3}$ edge with continues damage.