On the measurement of dislocation core periods by nanodiffraction

Multiple-scattering calculations are used to demonstrate that the periodicity of dislocation cores may be measured from coherent convergent beam patterns obtained using a subnanometre probe with the electron beam aligned with the dislocation core. The resulting ‘half-order’ high-order Laue zone ring which results from a double-period core reconstruction is shown to be detectable above the background of thermal diffuse scattering. Multiple-scattering calculations which include thermal scattering are used to show the temperature and thickness dependences of this ring. Activation energies for core processes may be obtained by this method.