Minerals at the atomic scale – new frontiers in atom probe tomography

Full text: Atom probe tomography is a powerful microscopy technique that provides beautiful three-dimensional 'maps' that show the position and elemental species of tens of millions of atoms in a given volume within a material, with a resolution on par with the most advanced electron microscopes. It has seen widespread use for the characterisation of bulk metals and alloys, but new developments in specimen preparation and the use of lasers to enable the study of less conducting materials have now made it applicable to the study of a much wider range of material types. Our atom probe techniques, originally driven by the needs of researchers investigating structural materials, has proven useful in other disciplines. This presentation will include recent work with geoscientists that provides information to more accurately date zircon, i.e., to determine the age of rocks. Atom probe data, reveals that the lead (Pb) used to date the mineral can diffuse through regions of the rocks that have experienced deformation events. This information is essential for accurate geochronological dating, showing that measurements from deformed areas of zircon are not as robust as previously thought. The presentation will also cover work undertaken in collaboration with dental researchers to provide the first-ever atom maps from human dental enamel, the decay of which affects 60- 90% of children and nearly 100% of adults worldwide. The results provided the first direct evidence for the presence of a proposed amorphous Mg-rich calcium phosphate phase that plays an essential role in governing the properties of teeth. The impact of these findings are expected to be wide-reaching: Treatments to avoid decay will be designed to protect against the dissolution of this specific amorphous phase, mechanical models will incorporate the true properties of the binding phase and research into methods to remineralise teeth will be able to incorporate a better understanding of how enamel forms. (author)