Preparation of high-quality ultrathin transmission electron microscopy specimens of a nanocrystalline metallic powder
Article first published online: 1 DEC 2011
Copyright © 2011 Wiley Periodicals, Inc.
Microscopy Research and Technique
Volume 75, Issue 6, pages 711–719, June 2012
How to Cite
Riedl, T., Gemming, T., Mickel, C., Eymann, K., Kirchner, A. and Kieback, B. (2012), Preparation of high-quality ultrathin transmission electron microscopy specimens of a nanocrystalline metallic powder. Microsc. Res. Tech., 75: 711–719. doi: 10.1002/jemt.21116
- Issue published online: 21 MAY 2012
- Article first published online: 1 DEC 2011
- Manuscript Accepted: 10 OCT 2011
- Manuscript Received: 21 APR 2011
- Deutsche Forschungsgemeinschaft via Emmy Noether program
- TEM specimen thickness;
- ion beam milling;
- nanocrystalline materials
This article explores the achievable transmission electron microscopy specimen thickness and quality by using three different preparation methods in the case of a high-strength nanocrystalline Cu–Nb powder alloy. Low specimen thickness is essential for spatially resolved analyses of the grains in nanocrystalline materials. We have found that single-sided as well as double-sided low-angle Ar ion milling of the Cu–Nb powders embedded into epoxy resin produced wedge-shaped particles of very low thickness (<10 nm) near the edge. By means of a modified focused ion beam lift-out technique generating holes in the lamella interior large micrometer-sized electron-transparent regions were obtained. However, this lamella displayed a higher thickness at the rim of ≥30 nm. Limiting factors for the observed thicknesses are discussed including ion damage depths, backscattering, and surface roughness, which depend on ion type, energy, current density, and specimen motion. Finally, sections cut by ultramicrotomy at low stroke rate and low set thickness offered vast, several tens of square micrometers uniformly thin regions of ∼10-nm minimum thickness. As major drawbacks, we have detected a thin coating on the sections consisting of epoxy deployed as the embedding material and considerable nanoscale thickness variations. Microsc. Res. Tech. 75:711–719, 2012. © 2011 Wiley Periodicals, Inc.