EFFECT OF TEMPERATURE AND RECOIL-ENERGY SPECTRA ON IRRADIATION-INDUCED AMORPHIZATION IN CA2LA8(SIO4)6O2

Single crystals of Ca2La8(SiO4)6O2 have been irradiated with different ions/energies in an in-situ study of the effects of temperature and recoil-energy spectra on irradiation-induced amorphization. The dose for complete amorphization (approximately 0.36 dpa) is independent of recoil-energy spectra at 15 K and-increases with temperature in two stages. The low-temperature stage (below approximately 200 K) has an activation energy of 0.01 +/- 0.003 eV and may be associated with simultaneous close-pair recombination. The high-temperature stage (above approximately 200 K) has an activation energy of 0. 13 +/- 0.02 eV and may be associated with irradiation-enhanced defect mobility. The critical temperature for amorphization increases from approximately 360 K for 0.8 MeV Ne+ to approximately 710 K for 1.5 MeV Kr+. The amorphization dose increases more rapidly with temperature for Ne+ due to the larger fraction of recoverable defects produced by the low energy recoils.