Semester Projects | Fall 2023

(can be adapted to Bachelor or Master level)

Evaluation of the effects of various filters for 4D-STEM data processing
Available

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a promising technique to measure the electric field of a potential induced process in an electron microscope. In these experiments, the interaction between the electron beam and the electric field causes a shift in the beam position (Lorentz-like interaction), which can be measured to map the field. One of the major challenges in 4D-STEM experiments lies in the data processing procedure used to track the beam shift, such as center of mass of template matching, which is complicated by the effect of diffraction contrast that makes the intensity of the beam inhomogeneous. The aim of the project is to develop a robust data filtering procedure for 4D-STEM experiments that improves the detection of beam deflection. This procedure is particularly challenging due to the subpixel-scale nature of the beam shift that needs to be detected. The reliability of the results will be assessed by comparison with a COMSOL simulation of the experiment (which will not be performed by the student). Python is the preferred programming language for this project. However, alternative tools such as ImageJ or MATLAB can also be used, as long as the file format is unchanged (TIFF).

Contact: Mr. Pierpaolo Ranieri
 
 
Exploring the impact of electrolyte on oxide catalysts for the oxygen evolution reaction
Reserved

Materials that catalyze the oxygen evolution reaction (OER) is at the forefront of clean and sustainable renewable energy production technologies. Catalysts stabilize intermediates and enhance the reaction efficiency. However, designing the ideal catalyst requires a detailed study of each step of the process. This project involves employing electrochemical methods such as cyclic voltammetry and open-circuit voltage measurements. The student will conduct a series of experiments in a microvolume liquid cell using MEMS chips, with a specific focus on investigating the impact of electrolyte composition on the activity and stability of transition metal oxide catalysts.

Contact: Ms. Elizaveta Shcherbacheva
 
 
Preparation of rechargeable battery electrodes and their cycling in microcells
Unvailable

There is significant research dedicated to rechargeable batteries with the current technology based on lithium ion processes remaining the candidate of choice for further enhancements. These include cathode electrodes based on novel materials due to the fact that the degradation of the cathodes remains the main reason for capacity decay. Electron microscopy experiments can provide unique insights into the degradation processes and can be performed in real-time, however the modification of the bulk cell to a microcell configuration requires optimisation of the system. In detail, the student will work on the battery assembly that includes the ink preparation for the cathode and counter electrodes, the dropcasting, the evaluation of adhesion to the current collector, and its cycling ex-situ at the first instance.

Contact: Mr. Morgan Binggeli
 
 
Microfabrication of chips for graphene membrane-based microcells
Available

The aim of this project is to fabricate MEMS-based electrochemical chips with integrated graphene membrane for high-resolution imaging in liquid-phase TEM. The student will be introduced to microfabrication processes inclusive of photolithography, thin film deposition, dry and wet etching. The student will acquire hands-on experience in MEMS fabrication processes. Previous hand-on experience in cleanroom is preferred for this project.

Contact: Ms. Saltanat Toleukhanova
 
 
Simulating atomic defects in Bi2Se3
Reserved

Step into the world of topological insulators and electron microscopy with Bi2Se3. This material possesses surface-conducting states with locked spins, opening doors to breakthroughs in spintronics, optoelectronics, quantum computing and beyond. Yet, the presence of Se vacancies arising from Bi-Se off-stoichiometry introduces a non-polarized current component, limiting its potential. Although these defects have not been observed directly, scanning transmission electron microscopy (STEM) has the potential to reveal them under appropriate conditions. In this project, the student will optimize the configuration of the microscope and specimen to precisely identify atomic defects. This will be achieved through systematic simulations (using JEMS and Dr Probe) of S/TEM images of defective Bi2Se3 crystals.

Contact: Dr. Saul Estandia
 
 
SEM imaging of Cu nanocatalysts under CO2 electroreduction conditions
Reserved

Studying catalysts’ restructuring behavior under CO2 reduction conditions is important for identifying their degradation mechanism. Liquid-cell electron microscopy allows real-time imaging of materials under controlled biasing conditions. The aim of this project is to study Cu nanocatalyst restructuring behavior under CO2 reducing conditions. In the first part of the project the student will perform a series of control experiments to identify the best imaging conditions for graphene-based liquid cells. In the second part, the student will perform imaging of nanocatalysts under CO2 reducing conditions to track their morphological evolution. The student will gain hands-on experience in SEM operation, liquid electrochemical microcell processes and analysis of SEM data.

Contact: Ms. Saltanat Toleukhanova
 
 
Sample preparation design by finite element methods for in-situ TEM biasing experiments
Available

Sample preparation is critical for the success of in-situ biasing experiment where this consists in preparing a thin lamella of the material of interest and placing it on a nano-chip patterned with electrodes that allows to control the different conditions during the observation. The aim of the project is to design a sample preparation procedure that will be realized afterwards in a real experiment. The student will investigate the effect of different design conditions, including the shape of the lamella, its position on the chip, and the design of the chip itself (the distance between two electrodes) using finite element methods (FEM), a tool used to solve partial differential equations in a wide range of physics problems, such as structural analysis, heat transfer, fluid flow, mass transport, and electromagnetic potential.

Contact: Mr. Pierpaolo Ranieri