Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 15: Poster Session

MM 15.80: Poster

Monday, March 11, 2013, 18:00–20:00, Poster E

Quantitative study of electron-radiation damage by in situ EFTEM investigations of the phase transformation from CaCO₃ to CaO at 80 kV, 40 kV and 20 kV — •Werner Schweigert¹, Ute Golla-Schindler¹, Gerd Benner², and Ute Kaiser¹ — ¹Group of Electron Microscopy of Materials Science, Central Facility of Electron Microscopy, 89081 Ulm, Germany — ²Carl Zeiss NTS GmbH, Application TEM / Materials Analysis, 73447 Oberkochen Germany

The TEM investigation showed that under electron irradiation a phase transformation from CaCO₃ to CaO occur. (This is the transformation route for CaO (quicklime) production out of calcite, taking place at elevated temperatures of 900 ^∘C.) The phase transformation is accompanied by a strong volume loss of the particles. We developed a method for measuring quantitatively the volume loss in dependence of the particle thickness and the accelerating voltage of the microscope. The determination of the volume is divided in two parts. Our method for segmenting the image into vacuum and particle is an edge detection process based on the canny algorithm. The thickness can be measured with the log-ratio method. The TEM investigations were performed on the SALVE (Sub-Angström Low-Voltage Electron) prototype microscope equipped with an image-side Cs-corrector, a field emission gun, a monochromator and a corrected in-column OMEGA energy filter. TEM studies were performed at 20, 40, 80 kV. We found that the volume-loss is dose-rate dependent and increases with lower voltages; the contrast however is increasing.