5:15 PM - 6:30 PM
[SMP25-P18] Meliorating the spatial resolution of SEM-EBSD
Keywords:SEM-EBSD, Spatial resolution, Quantitative microanalysis
Electron Backscatter Diffraction (EBSD) is a commonly applied analytical practice for quantitative analysis in the scanning electron microscope (SEM). The spatial resolutions of SEM-EBSD are known to be about a few μm for the tungsten filament electron gun SEM and a few tens of nm for the Schottky field-emission electron gun SEM.
Quartz grain size provides important information regarding the flow stress during the plastic deformation of mylonite (Stipp and Tullis, 2003). Some mylonite samples contains quartz grains with size of smaller than 1 μm (Okudaira and Shigematsu, 2012). It has been described that these quartz grains developed through dynamic recrystallisation mechanism. Thus, a higher spatial resolution is required during EBSD mapping in order to fully represent the microstructures of such sub-micro scale grains and techniques to meliorate the spatial resolution is essential for this purpose.
The SEM used for this study is located in the GSJ laboratory of AIST, Japan with a Hitachi SU-3500 (W filament gun SEM) and HKL Nordlys EBSD sensor. Quartz, a common mineral on the continental crust is first chemo-mechanically polished with colloidal silica before the analysis. The investigation was preformed with the sample coated with a 0.2 nm thick Osmium coating to reduce the charging effects.
There is a trade-off between the spatial resolution and the signal intensity of the EBSD, which is control by the probe diametre and accelerating voltage. This trade-off was investigated by adjusting the objective lens movable aperture, condenser lens and accelerating voltage to obtain the most optimal condition. The spatial resolution is qualitatively and quantitatively analysed from the kikuchi bands images obtained through a line profile. We investigated the spatial resolution for both X (parallel to the tilt axis) and Y axes (perpendicular to the tilt axis) as samples used for EBSD analysis are generally tilted at 70°, thus yielding different spatial resolutions at both X and Y directions.
The knife-edge method was also applied to measure the beam diameter at different optical conditions. In this presentation, we show the preliminary results.
Quartz grain size provides important information regarding the flow stress during the plastic deformation of mylonite (Stipp and Tullis, 2003). Some mylonite samples contains quartz grains with size of smaller than 1 μm (Okudaira and Shigematsu, 2012). It has been described that these quartz grains developed through dynamic recrystallisation mechanism. Thus, a higher spatial resolution is required during EBSD mapping in order to fully represent the microstructures of such sub-micro scale grains and techniques to meliorate the spatial resolution is essential for this purpose.
The SEM used for this study is located in the GSJ laboratory of AIST, Japan with a Hitachi SU-3500 (W filament gun SEM) and HKL Nordlys EBSD sensor. Quartz, a common mineral on the continental crust is first chemo-mechanically polished with colloidal silica before the analysis. The investigation was preformed with the sample coated with a 0.2 nm thick Osmium coating to reduce the charging effects.
There is a trade-off between the spatial resolution and the signal intensity of the EBSD, which is control by the probe diametre and accelerating voltage. This trade-off was investigated by adjusting the objective lens movable aperture, condenser lens and accelerating voltage to obtain the most optimal condition. The spatial resolution is qualitatively and quantitatively analysed from the kikuchi bands images obtained through a line profile. We investigated the spatial resolution for both X (parallel to the tilt axis) and Y axes (perpendicular to the tilt axis) as samples used for EBSD analysis are generally tilted at 70°, thus yielding different spatial resolutions at both X and Y directions.
The knife-edge method was also applied to measure the beam diameter at different optical conditions. In this presentation, we show the preliminary results.