Environmental TEM for Micro- and Nanostructure Research

• Applicant: Professor Dr. Benjamin Butz
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 286873388

In materials science, both, development of novel materials and in depth analysis of the failure of employed materials strongly rely on electron microscopic and spectroscopic methodology. Especially, recent developments in transmission electron microscopy (TEM) like high-speed spectrometers, cameras and of course aberration correctors significantly contribute to successful research. However, for many functional materials in catalysis or energy conversion (batteries, fuel cells) as well as structural alloys (corrosion-resistant steel, super alloys, biocompatible alloys) and ceramics (high-temperature/biocompatible ceramics), TEM investigation under application-relevant environmental conditions would be beneficial. Aberration-corrected environmental TEM (ETEM), still being rather exotic, provides the exceptional opportunity to in situ study microstructure, crystal structure, local composition and atomic bonding/oxidation state exactly under those conditions down to the atomic scale, meaning to study materials at temperatures in the range from room temperature above 1000 °C in almost any gaseous environment ranging from highly reducing to oxidizing conditions. Moreover, gaseous precursors can be introduced into nowadays instruments to observe, e.g., catalytically activated formation of nanostructures. The major objective of this project is to apply ETEM to solve dedicated materials science issues in different fields of application like catalysis, energy conversion and novel carbon-based functional materials: i) Structure formation in metallic/metal oxide nanoparticles/-structures using model systems and real materials - Quantitative comparison of ETEM to the inert-gas transfer of ex situ prepared TEM samples using glove box + vacuum-transfer holder (which might be applicable to a wide range of materials and for many groups who do not operate a dedicated ETEM instrument), ii) Environment-dependent conductivity degradation of Ni-containing yttria-stabilized zirconia (YSZ) ceramics at high temperatures - Characterization of the inherent chemical decomposition and accompanied phase transformations especially in reducing atmosphere on the nm-scale, iii) Electron-beam induced and gas-phase assisted reduction of high-quality monolayer graphene oxide - Evolution of microstructure and chemical bonding upon reduction on the molecular scale. Working on most different material classes will allow for compilation of current experimental limitations of ETEM, which is essential for the community to best design own ETEM experiments and, moreover, to identify prospective developments in this field.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Robert Sinclair