Research Highlights 2013

Phase Contrast in STEM

Phase-contrast STEM imaging in an aberration-corrected microscope represents an increasingly important alternative to the well-established HRTEM method. In both methods, the image contrast is coherently generated and thus depends not only on illumination and collection angles but on defocus and specimen thickness as well. This can be understood on the basis of the reprocity principle as demonstrated in this review. The application of PC-STEM is demonstrated by the image of LiBC shown above that reveals the positions of all atoms in the graphite-related structure.

Phase-Contrast Imaging in Aberration-Corrected Scanning Transmission Electron Microscopy
F. Krumeich, E. Müller, and R. A. Wepf
Micron 49 (2013) 1-14 DOI

Characterization of LiBC by Phase-Contrast Scanning Transmission Electron Microscopy
F. Krumeich, M. Wörle, P. Reibisch, and R. Nesper
Micron 63 (2014) 64-68 DOI

Tin Nanocrystals for Battery Applications

Uniform and monodisperse Sn and Sn/SnO₂ nanoparticles can be obtained with sizes in the range 9-23 nm. In electrochemical measurements, 10 nm Sn/SnO₂ nanocrystals have demonstrated high Li insertion/removal cycling stability superior to commercial 100−150 nm powders of Sn and SnO₂.

Monodisperse and Inorganically Capped Sn and Sn/SnO₂ Nanocrystals for High Performance Li-ion Battery Anodes
K. Kravchyk, L. Protesescu, M. Bodnarchuk, F. Krumeich, M. Yarema, M. Walter, C. Guntlin, and M. Kovalenko
J. Am. Chem. Soc. 135 (2013) 4199-420 DOI

Recent Research Hightlights