Nanoscale analysis of three-dimensional structures by electron tomography

A significant challenge to the design of nanoscale materials and devices is the difficulty of characterising complex three-dimensional structures on small length scales. Electron tomography, a technique pioneered in the life sciences, has been developed for materials science by using high-angle annular dark-field scanning transmission electron microscopic tomography and energy filtered transmission electron microscopic tomography. We present tomographic analyses that reveal three very different types of information: the crystal habit of magnetite in magnetotactic bacteria, the morphology and composition of a silicon–germanium quantum dot, and compositional variations in iron–nickel nanoparticles. Both techniques are shown to return chemical and structural information that would be unattainable using conventional two-dimensional microscopy.