An investigation was made of the instability mechanisms of extended interstitial defect clusters (charged dislocation loops) which formed in stabilized cubic zirconia, under 100 to 1000keV electron irradiation, due to selective displacement damage in the O sub-lattice. A new theoretical model was suggested for the growth and instability of interstitial clusters. The model took account of an accumulation of effective charge, on growing dislocation loops, due to the trapping of electrons in dislocation cores. The calculations showed that the elastic stress and strain fields were more intense around charged dislocation loops than around non-charged dislocation loops; due to additional stress and strain fields which were driven by the electric field of accumulated charge. The stress which was induced by charged dislocation loops, with 0.4 trapped electrons per atom, was comparable to the theoretical yield stress of zirconia. This explained an experimentally observed increase in the dislocation network at a critical defect-cluster size.

Instability of Interstitial Clusters under Ion and Electron Irradiation in Ceramic Materials. A.I.Ryazanov, K.Yasuda, C.Kinoshita, A.V.Klaptsov: Journal of Nuclear Materials, 2003, 323[2-3], 372-9