Defect production and amorphisation due to energetic uranium recoils in zircon (ZrSiO4), which is a promising ceramic nuclear waste form, is studied using molecular dynamics simulations with a partial charge model. An algorithm that distinguishes between undamaged crystal, crystalline defects and amorphous regions is used to develop a fundamental understanding of the primary damage state. The amorphous cascade core is separated from the surrounding crystal by a defect-rich region. Small, chemically inhomogeneous amorphous clusters are also produced around the core. The amorphous regions consist of under-coordinated Zr and polymerised Si leading to amorphisation and phase separation on a nanometer scale into Zr- and Si-rich regions. This separation could play an important role in the experimentally observed formation of nanoscale ZrO2 in ZrSiO4 irradiated at elevated temperatures.
Revised: January 10, 2007 |
Published: October 11, 2006
Citation
Devanathan R., L.R. Corrales, W.J. Weber, A. Chartier, and C. Meis. 2006.Molecular Dynamics Simulation of Energetic Uranium Recoil Damage in Zircon.Molecular Simulation 32, no. 12-13:1069-1077.PNNL-SA-50764.