Strain fields and line energies of dislocations in uranium dioxide

Abstract

Computer simulations are used to investigate the stability of typical dislocations inuranium dioxide. We explain in detail the methods used to produce the dislocationconfigurations and calculate the line energy and Peierls barrier for pure edge and screwdislocations with the shortest Burgers vector . The easiest slip system is found to be the{100}⟨110⟩ system forstoichiometric UO2, in agreement with experimental observations. We also examine the differentstrain fields associated with these line defects and the close agreement betweenthe strain field predicted by atomic scale models and the application of elastictheory. Molecular dynamics simulations are used to investigate the processes of slipthat may occur for the three different edge dislocation geometries and nudgedelastic band calculations are used to establish a value for the Peierls barrier,showing the possible utility of the method in investigating both thermodynamicaverage behaviour and dynamic processes such as creep and plastic deformation.