TEM Examples

Method Development

While state-of-the-art electron microscopy techniques are extremely powerful, some research problems require dedicated method development to answer challenging structural or functional questions.

We are focusing on three main methdology areas in repsonse to the needs of our collaborations partners, developing approaches for dedicated structural and functional analysis of materials at the atomic or nanoscale.

In-situ TEM

In-situ and operando TEM provides a direct link between structural evolution and materials properties or function and the ability to identify transient structures, which cannot be observed ex-situ. We are using and optimizing the techniques, combining them in particular with various 4D-STEM and spectroscopic techniques.

  • Mechanical testing
  • Heating
  • Cooling
  • Biasing
  • Electrochemistry
  • Gas environment
In-situ TEM Atmosphere Holder Protochips Inc.
In-situ TEM

Heating, biasing, electro-chemistry, gas environment, mechanical deformation

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4D-STEM

4D-STEM techniques have been shown to be extremely powerful, opening the possibility of high-end structural characterization using ptychography, pair distribution function mapping or quantitative crystal orientation analysis as well as functional characterization by quantitatively measuring magnetic or electric field distributions.

  • ACOM-STEM: Crystal orientation mapping
  • STEM-PDF: Atomic pair distribution function mapping for local atomic bonding and coordination in disordered and amorphous materials
  • STEM-DPC and STEM-iDPC: Differential phase contrast imaging for local mean potential and magnetic field imaging
4D-STEM Xiaoke Mu, KIT
4D-STEM

Automated crystal orientaton mapping

Pair distrubution function mapping

Differential phase contrast

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Electron Tomography

We are developing electron tomography as an approach to quantify the 3D nano and micro structure. In collaborations, we are using this experimental 3D structure as basis for diffusion or flow simulations.

  • STEM tomography
  • EDX tomography
  • FIB Slice & View
  • Quantitative tomography analysis
Electron Tomography in Catalysis Wu Wang, KIT
Electron Tomography

Quantitative 3D nanoscale and microscale analysis

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Supporting Developments

Electron Beam Damage

While radiation damage in electron microscopy is no research topic by itself, understanding the implications especially for in-situ TEM is absolutely essential for a meaningful interpretation of results. Therefore, it is important to develop approaches to evaluate damage in different materials and at different levels. In addition to the well established approach follwoing the fading of the diffraction pattern, we are using PDF analysis to look into changes in armohpous materials and understand the different steps of the degradation. Independent of the structural changes, in-situ conductivity measurements turned out to be a very sensitive probe of beam induced functional changes in materials.

Sample Handling

Sample handling, in particular of air sensitive samples, can be challenging and often limits practical work. Therefore, we are working on approaches to prepare dedicated samples for TEM testing and remote controled approaches to handle TEM grids.

In addition, we are developing improved approaches for FIB prepration, minimizing the mechanical impact and the electron/ion dose and gas injection needed for TEM sample preparation to provide samples as closely as possible representing the native state of a material for further analysis.

 

Research Data Management

Research Data Management (RDA) aims to make the research process as efficient as possible by providing structured access to information, meeting expectations and requirements of the university, research funders, and industry as well.

RDM Mehrdad Jalali, KIT
Research Data Management

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