Materials Research Society

High-Resolution TEM of Layered Crystals and Incommensurate Misfit Layer Compounds and Their Interfaces

Wolfgang Jäger
Microanalysis of Materials, Institute of Materials Science, Christian-Albrechts-University, Kiel, Kaiserstraße 2, 24143 Kiel, Germany, EU

Materials research for advanced nano-scale and thin film materials, layered structures and interfaces has established itself as a fascinating and attractive research field because of its fundamental importance in understanding the chemical and physical properties of these materials and in evaluating their potential for technological applications. Advanced high-resolution imaging and spectroscopic techniques of electron microscopy play a crucial role in characterizing the microstructure and the structure-property relationships and in the metrology of nanomaterials and interfaces. The presentation will summarize investigations of interface and surface phenomena of transition metal dichalcogenide crystals, with a focus on self-assembled surface nanofolds and metal intercalation for layered chalcogenide crystals1,2,3 and on the effects of interface incommensurability in epitaxial layers4 and in misfit layer compounds5,6. First investigations of the incommensurate misfit layer compound (PbS)1.14NbS2 using aberration-corrected high-resolution TEM under imaging conditions with negative values of the spherical aberration coefficient Cs (NCSI-contrast) demonstrate that direct imaging of light atomic columns (S) and heavy atomic columns (mixed Pb/S) becomes possible, thus enabling to locally investigate interfaces, layer distortions, and stacking disorder6.
References:

6. M. Garbrecht, E. Spiecker, W. Jäger, K. Tillmann, Aberration-corrected HRTEM of the incommensurate misfit layer compound (PbS)1.14NbS2, Mater. Res. Soc. Symp. Proc. Vol. 1026 © 2008 Materials Research Society 1026-C10-01
5. E. Spiecker, M. Garbrecht, C. Dieker, W. Jäger, U. Dahmen, High-resolution TEM and diffraction study of layer stacking and long-period undulations in the incommensurate misfit layer compound (PbS)1.14NbS2 , Microsc. Microanal. 13 (Suppl.3), 424-425 (2007)
4. E. Spiecker, W. Jäger, J. Brandt, L. Kipp: Anisotropic film strain and dislocation pairing induced by uniaxial interface incommensurability, Proc. 16th Int. Microscopy Congress IMC-16. Sapporo, Japan, Eds. H. Ichinose, T. Sasaki, Vol. 3, 1369 (2006).
3. E. Spiecker, A. Schmid, A. Minor, U. Dahmen, S. Hollensteiner and W. Jäger: Self-Assembled Nanofold Network Formation on Layered Crystal Surfaces during Metal Intercalation. Phys. Rev. Lett. 96, 086401 (2006).
2. S. Hollensteiner, W. Sigle, E. Spiecker and W. Jäger (2005): Combined EELS, EDX and STEM investigations of Cu-induced nanostructures and thin surface layer phases. Z. Metallkunde, 96, 888–893 (2005)
1. S. Hollensteiner, E. Spiecker, W. Jäger (2004). Metal-Induced Nanostructures on Surfaces of Layered Chalcogenides. Appl. Surf. Sci., 241, 49 - 55 (2005).
We acknowledge funding by the German Science Foundation (DFG FOR 353, SP648) and the contributions of our colleagues and co-authors on the related publications.