Sample Stage for Fast, Continuous Tomography in In Situ Transmission Electron Microscopy

Current tomography holders do not allow dynamic experiments. Furthermore, the slow nature of data acquisition limits their use to materials that are robust under the electron beam. With the advancement of direct electron detectors, several functional materials that are electron beam sensitive such as perovskites, metal organic frameworks and lithium ion battery materials can now be studied in 3D by electron tomography. However, the current methods use the microscopeĺs goniometer to tilt the sample, which limits the speed of data acquisition and also has a limit in its tilt range, resulting in artifacts in the reconstruction due to the presence of a ômissing wedgeö. We have developed a prototype rotates the sample 360° as opposed to the conventional approach in which the rod is rotated by the goniometer. In Phase I, we prototyped a piezodriven continuously rotation tomography holder and an in situ heating tomography holder. Successful implementation of such in situ holders will also need a user-friendly acquisition software, for which we are collaborating with the National Center of Electron Microcopy, Berkeley Lab. We propose to continue this development in Phase II and hope to develop commercially viable specimen holders for electron microscopes with the following features. 1) Improved piezo-driven continuous rotation tomography holder with higher concentricity 2) In situ tomography holders: Features such as heating and biasing will be added to the tomography holder so that researchers can record time-resolved 3D data. 3) Develop a control system: A feedback control system will be developed connecting the holder, detector and the microscopeĺs stage using Python that will allow users to perform in situ tomography experiments from a single program. For the second phase of the project, we would i) Implement autofocusing and auto tracking features in the Python-based acquisition software and add acquisition software to record tilt series with spectroscopy data, 2) Develop a more robust continuous rotation tomography holder and its heated version, 3) Develop tungsten needle-based tip that allows missing wedge-free tilt series acquisition, 4) Develop a prototype for a MEMS-based in situ biasing/heating continuous rotation tomography holder, 5) Develop a Peltier-cooled in situ heating continuous rotation tomography holder and 6) Develop a prototype for a continuous rotation cryo tomography holder. Electron tomography holder with in situ capabilities can be used to understand failure mechanisms in various materials of interest in energy harvesting and storage applications.