Temperature dependence of electron-beam induced effects in amorphous apatite

Irradiation effects on pre-amorphized Sr2Nd8(SiO4)6O2 have been investigated under 200 and 300 keV electron-beam (e-beam) irradiation at 130 and 480 K using in situ transmission electron microscopy. At 480 K, recrystallization occurred from the amorphous/crystalline interface under both 200 and 300 keV e-beam irradiation. At 130 K, the 200 keV e-beam irradiation induced recrystallization only; however, 300 keV e-beam irradiation induced both recrystallization and an electron hammering effect in the amorphous material that resulted in radial expansion perpendicular to the incident e-beam direction and shrinkage parallel to the e-beam direction. Ionization-induced processes and knock-on displacement damage are suggested to be the mechanisms for the recrystallization and the electron hammering effect, respectively.