Molecular dynamics simulation of the α-recoil nucleus displacement cascade in zirconolite

Molecular dynamics simulation with Buckingham empirical potentials has been used to study irradiation damage in crystalline zirconolite (CaZrTi2O7). Threshold displacement energies have been calculated and displacement cascades (DCs) initiated by α-decay recoil nuclei have been modeled. DCs result in an highly disordered core around the track of the projectile surrounded by a distribution of isolated point defects. The number and types of point defects created by the cascades are calculated. Radial distribution functions of ions in the disordered core are intermediate between the ones of crystalline and amorphous zirconolite. The simulated cascades are consistent with the experimentally observed direct impact amorphization associated with phase transitions in the crystalline areas.