Effect of temperature and recoil-energy spectra on irradiation-induced amorphization in Ca{sub 2}La{sub 8}(SiO{sub 4}){sub 6}O{sub 2}

Abstract

Single crystals of Ca,,l..,as(SiO4)60_ " have been irradiated with different ions/energies in an in situ study of the effects of temperature and recoil-energy spectra on irradiation-induced amorphizatio,. The dose for compete amorphization increases with temperature in two stages. The low-temperature stage (below 250 Ix-'),. has an activation energy of 0.01 _.+ 0.003 eV and is believed to be associated with simultaneous close-pair recombination. The high-temperature stage (above 250 K) has an activation energy of 0.1.3 __.0.02 eV and may be associated with irradiation-enhanced defect mobility. The critical temperature for amorphization increases from-360 K for 0.8 MeV Ne* to-710 K for 1.5 MeV Kr*. At 15 K, the amorphization dose is-0.36 dpa and is independent of recoil-energy spectra. The amorphization dose increases more rapidly with temperature for Ne" due to the larger fraction of mobile defects produced by the low energy recoils. The temperature dependence is similar for 1.