MRI: Development of a Dynamic Atom Probe

Colorado School Of Mines, Golden CO

Investigators

Abstract

Technical Summary: Atom probe tomography (APT) is a materials characterization technique widely recognized as having the highest combined spatial and chemical resolution currently available. Limitations to true atomic scale APT still exist, however, including 3-D volume reconstruction following data acquisition and the lack of knowledge of specimen geometries either a-priori or during analysis. Additionally, 3-D atomic scale information combined with sub-ns temporal resolution is now a technological possibility. This project aims to develop a Dynamic Atom Probe (DynAP) capable of (1) in-situ monitoring of specimen geometry during atom probe field evaporation experiments for substantially improved APT reconstructions and (2) ultrafast electron diffraction in conjunction with APT to enable monitoring of thermally induced atomic scale motions for the first time. These goals will be accomplished using a combination of APT with scanning transmission electron microscopy and an ultrafast laser pump / electron diffraction probe experiment. The completed instrument will allow for sub-nm spatial resolution, 10^17 atoms / cm^3 chemical resolution, and sub-ns temporal resolution. DynAP will be used to probe atomic scale processes such as the effects of solute drag on grain boundary and dislocation motion, the kinetics of crystallization in amorphous semiconductors and metallic and ceramic glasses, and displacive phase transformations in metallic and ceramic systems. The instrument will be developed by researchers at the Colorado School of Mines in close collaboration and consultation with Atom Probe manufacturers. A portion of the instrumentation time will be utilized for outreach to and training of a diverse group of next generation scientists. Layman Summary: The ability to directly image how materials behave at high processing temperatures, and to do so at the atomic scale, would enable scientists and engineers to develop the next generation of materials for structural, electronic, and energy storage applications. Unfortunately, most of these atomic scale processes occur faster than we are able to image using even state of the art microscopy techniques, some of which also suffer from a lack of chemical information. This program aims to overcome these limitations through the development of a Dynamic Atom Probe (DynAP). The DynAP will be the first instrument of its kind to enable 3-dimensional imaging and chemical identification at the atomic level with ultrafast time resolution, typically one billionth of a second. Studying these ultrafast atomic scale processes will enable advances in a wide range of materials, including structural metals for aircraft and automotive applications, high speed electronic devices and solar energy conversion, as well as the potential for storing hydrogen in engineered ceramics. The instrument will be developed by researchers at the Colorado School of Mines in close collaboration and consultation with Atom Probe manufacturers. A portion of the instrumentation time will be utilized for outreach to and training of a diverse group of next generation scientists.