Molecular dynamics modeling of irradiation damage in pure and uranium-doped zircon

Molecular dynamics (MD) with empirical potentials of the Born-Mayer-Hugging s (BMH) type has been used to study irradiation damage in pure and uranium- doped zircon (ZrSiO4). Displacement threshold energies (DTE) have been calc ulated and displacement cascades (DC) initiated by a-decay recoil nuclei ha ve been modeled. A DC directly produces an amorphous core inside the cascad e track, with a structure identical to the one of fully amorphous material. The analysis of the disorder of cations first neighbors shell shows that t he cascade track has a concentrical shape with decreasing disorder from the core to the outer shell of the track. In the amorphous zone, some silicon atoms are connected to each other, indicating the appearance of SiO2-rich a nd ZrO2-rich nanophases. (C) 2001 Elsevier Science B.V. All rights reserved .