Thickness dependence of higher-order Laue zone line positions at strongly dynamic zone axes

Abstract

Simulation of bright-field convergent-beam electron diffraction (CBED) discs has revealed that, at zone axes where there are two strongly excited branches of the zero-layer dispersion surface that may interact with the HOLZ, the deficiency HOLZ line positions should be sensitive to changes in thickness. Examination of experimental patterns at carefully chosen accelerating voltages have corroborated the findings of the calculations. The effects are subtle; however, they are large enough to introduce significant errors into lattice parameter or strain measurements made by monitoring HOLZ positions. The magnitude of the effect is considerably reduced at zone axes where the dynamic diffraction is weaker (e.g. ), so much so that, with care, these axes are suitable for use in strain or lattice parameter determination.