Cyclic twinning and internal defects of boron-rich nanowires revealed by three-dimensional electron diffraction mapping.

Structural characterization of individual nanosized boron-rich nanowires has been carried out through analysing the three-dimensional (3D) electron diffraction intensity distribution. Not only can the cyclic twinning structure of these nanowires be easily determined, the new approach also reveals the heterogeneous strain relaxation within the intact nanowire, through the accurate determination of the orientation relationship between the constituent crystallites. The quantitative analysis of the fine structure in the 3D diffraction dataset indicates that this may be related to the distribution of defects such as stacking faults, microtwins and dislocations. It is envisaged that the non-destructive nature of this approach could open the way for the in situ study of the structural evolution of complex nanomaterials and polycrystalline materials in general.