Atomic-scale physical imaging and chemical mapping of functional nanomaterials using STEM-EDX technique
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Young-Min Kim Department of Energy Science, Sungkyunkwan University Center for Integrated Nanostructure Physics, Institute for Basic Science Scanning transmission electron microscopy (STEM)-based structural analysis at an atomic scale has become routine with the successful correction of aberrations of the probe-forming lens. Atomic positions in the structure can be determined even with picometer precision, revealing subtle changes in structural parameters in the unit cell-wise framework, which has been hitherto unsolved. Furthermore, recent advances in detector technology for energy-dispersive X-ray spectroscopy (EDX) enable us to resolve chemical composition of functional nanomaterials on the atomic scale, since this allows detection efficiency being about 10 times higher than that of conventional detectors. Notably, these high-end analytical techniques are simultaneously utilized in the same position of interest in samples. Taking advantage of the simultaneous, multiple imaging and probing capabilities, we can successfully identify which atoms are where in the unit cell, which is essential information in understanding quantum phenomena occurring in nanomaterials. In this talk, I will introduce how this STEM-based analysis is effectively used to solve materials problems arisen from manifold aspects of nanomaterials in terms of structure-property relationship. Particularly, I will discuss defect-mediated structural phenomena observed at the atomic-scale in some of functional nanomaterials such as thermoelectric materials and complex oxides as exemplar applications of atomic-scale STEM and EDX technique. |