Response of zircon to electron and Ne+ irradiation

Zircon (ZrSiO4) is an actinide host phase in vitreous ceramic nuclear waste forms and a potential host phase for the disposition of excess weapons plutonium. In the present work, the effects of 800 and 900 keV electron, and 1 MeV Ne+ irradiations on the structure of single crystals of ZrSiO4 have been investigated. The microstructural evolution during the irradiations was studied in situ using a high-voltage electron microscope interfaced to an ion accelerator at Argonne National Laboratory. The results indicate that electron irradiation at 15 K cannot amorphize ZrSiO4 even at fluences an order of magnitude higher than that required for amorphization by 1.5 MeV Kr+ ions. However, the material is readily amorphized by 1 MeV Ne+ irradiation at 15 K. The temperature dependence of this amorphization is discussed in light of previous studies of radiation damage in ZrSiO4.