In-situ TKD with Heating and Biasing
Dr. Vijay Bhatia
University of Sydney, Sydney, Australia
Date: Tuesday, December 1, 2020
Time: 9 AM Central European Summer Time (CEST) | 3 PM China Standard Time (CST)
Date: Wednesday, December 2, 2020
Time: 10 PM Central European Summer Time (CEST) | 1 PM Pacific Daylight Time (PDT)
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In-situ electron microscopy is an important pillar in the study of materials. Imaging samples after exposure to different stimuli and inferring the processes that have occurred creates the potential to miss key pieces of information. The advances of MEMS based heating and biasing chips for the TEM have enabled researchers to observe dynamic processes involving high temperatures (up to 1300°C) and/or through electrical biasing at the atomic scale. While this is a mature technique [1-2], the process of using these holders inside an SEM has not been largely documented [3-6]. By adapting this technology and combining it with the versatility of Transmission Kikuchi Diffraction (TKD) [7-8] it is possible to also observe the crystallographic changes that occur in the sample such as the texture of grains, phase transformations and, in some cases, strain measurements .
While in-situ TEM is a well established technique, many structural changes occur at the µm length scale. For example, in some nano-crystalline materials, phase transformations (like those seen in the figure below) and grain growth happen dynamically throughout the sample at different times and temperatures . The strength of TKD is in obtaining crystallographic information across, micron sized ROI at approximately 4nm resolution, therefore ensuring that statistically significant regions of the material are included in the data.
In this work we have shown the development and implementation of in-situ TKD on poly-crystalline materials under both heating and electrical biasing stimuli, including manganese steel and nano crystalline Cu. We discuss the development of the in-situ holder geometry for use in the SEM, as well as the limitations and future developments to improve the versatility. We also show how this can be used for correlative experiments between TKD and TEM.
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- The authors acknowledge the facilities and the scientific and technical assistance of the Microscopy Australia at the Australian Centre for Microscopy & Microanalysis at the University of Sydney.