"Are your nanostructures feeling the strain?"

01-05-2010: In collaboration with the Argonne National Laboratory, Dr. Marcus Newton of the Advanced Technology Institute at the University of Surrey and Professor Ian Robinson of the London Centre for Nanotechnology have for the first time mapped strain in three-dimensions in a single nanoscale object.

Nanoscale structures can be highly strained because of confinement effects and the strong influence of their external boundaries. This results in dramatically different electronic, magnetic and optical material properties of considerable utility. Third-generation synchrotron-based coherent X-ray diffraction has emerged as a non-destructive tool for three-dimensional imaging of strain and defects in crystals that are smaller than the coherence volume, typically a few cubic micrometres, of the available beams that have sufficient flux to reveal the material's structure. Until now, measurements have been possible only at a single Bragg point of a given crystal because of the limited ability to maintain alignment; it has therefore been possible to determine only one component of displacement and not the full strain tensor. The researchers report major advances in fabrication and experimental techniques, which have enabled diffraction patterns to be obtained from six Bragg reflections of the same ZnO nanocrystal for the first time. All three Cartesian components of the ion displacement field, and in turn the full nine-component strain tensor, have thereby been imaged in three dimensions.

Professor Ravi Silva, Director of the Advanced Technology Institute (ATI), comments: "We are very pleased with the quality of the work presented in this paper that maps out fundamental findings in materials characterisation that have profound implications for future device structures. The ATI has expertise that spans the materials sector from fundamental to applied technology. This is a prime example of fundamental research that can be applied to next generation electronic, magnetic and optical devices."

Original publication: "Three-dimensional imaging of strain in a single ZnO nanorod"; Nature Materials Letters 2009.