Atomic scale observations of interface structure and dynamics by electron microscopy
Ulrich Dahmen, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, USA
The development of aberration correction for electron microscopy has greatly increased our ability to characterize materials at the atomic scale. The same technological advances that have extended the resolution limit to 0.5Å have also made it possible to record images with better signal-to-noise and at faster rates. This has allowed us to observe atomic-scale mechanisms and dynamics of reactions in interfaces and to compare them directly with atomistic simulations. Using a technique of event detection and cumulative averaging in combination with Molecular Dynamics simulations, we have recently uncovered a mechanism of collective atomic motion responsible for the advance of steps in 90° tilt grain boundaries in Au. This mechanism is relevant to interface motion during grain growth and deformation. Examples of atomic-scale dynamic observations of interface motion will be shown and related to thermodynamic and structural parameters. Finally, this talk will also outline some recent developments in electron microscopy with a view toward future research on interfaces in materials.