WEBINARS
Extending TEM capabilities with Scanning Precession Electron Diffraction (PED)
Dr. Jing Lu, Application scientist NanoMEGAS USA
In this webinar, Dr. Jing Lu will explain how modern TEM microscopes benefit from PED, a breakthrough in electron crystallography, now commonly used for synchronized scanning and precession (4D-STEM). In this presentation we will show how the NanoMEGAS system provides streamlined PED acquisition with automated precession alignments and analysis featuring ASTAR orientation /phase mapping and Topspin strain mapping while achieving high spatial resolution and precision
ACOM/TEM (ASTAR) : Automated crystal orientation mapping with TEMs
Dr. Edgar Rauch SiMAP Laboratory CNRS France
In this webinar Dr. Rauch introduces the coupling of scanning Precession Electron diffraction patterns (4D-STEM) with template matching approach to generate orientation and phase maps (ASTAR system). As evidenced by the many published studies (more than 500 papers published using ASTAR since 2009) this technique is well suited to characterize local orientation and phase maps (up to 1-2 nm resolution) in metals , alloys, minerals , nanostructures etc.. Using virtual apertures in ASTAR/ 4D-STEM images and correlation coefficient maps, superimposed secondary phases, hidden dislocations /defects and amorphous areas can be clearly highlighted in the material under examination.
Applications of orientation and phase maps in metallurgy
Prof. Muriel Veron, CNRS Grenoble INP France
In this webinar Prof. Veron reviews important ASTAR (orientation & phase maps) applications in metallurgy, like in heavily deformed metals, precipitate identification, steels for nuclear applications, oxidation & corrosion studies in alloys, grain boundary studies and semiconductor interconnects. The use of “virtual dark field apertures” allows to study nanocrystalline and amorphous areas. In this webinar will be also presented ASTAR examples from geology (analysis of heavily deformed mineral structures) and life science (bone mineralization) from various laboratories around the world.
Combining in situ TEM and Orientation mapping /understanding the deformation and annealing
Dr. Christian Kuebel KIT , Germany Institute of Nanotechnology
In this webinar, Dr. Kuebel is presenting the work of his team in relation of how external stimuli (biasing, deformation, gas, heating) can provide direct information on materials properties and performance. In particular he is showing how ASTAR can reveal information down to nm scale on grain boundary type and orientation, grain size, phase & orientation distribution after a deformation process. He is presenting examples about texture evolution (grain structure & grain´s correlations) during deformation process as well as in situ phase formation during thermal annealing of nanocrystalline compositionally complex alloys .
Advance Characterization of materials using PED /ACOM (ASTAR)
Dr. Partha Ghosal, DMRL India
In this webinar, Dr. Ghosal he is presenting various examples of how the combination of advanced characterization techniques (ASTAR with 3D diffraction tomography) are critical to understand material´s structural properties with processing conditions. In the first example characterization of brittle Ni-Cr-W fuel manifold in R-29 Aero-engine by ASTAR phase and orientation mapping in TE. A detailed study using 3D diffraction tomography revealed a novel Cr-rich M23C6 carbide cubic phase (a=9.6 nm) responsible for the failure.
In the second example oxidation resistant Pt-aluminide coatings (applied to advanced gas turbine engine component for enhancing high temperature capability) were studied with ASTAR. That present study examines the role of local microstructure on tensile failure mechanism of PtAl coatings. In the third example TiAlTaCrBC phase was studied by ASTAR phase and orientation mapping, which is used for turbine blade applications. Studies of this phase are important to understand the effects of minor elements on the microstructure.
Local structure at the nanoscale (e-PDF)
Prof. Simon Billinge , Columbia University
The study of nanocrystalline or amorphous materials can be optimally performed with Electron Pair Distribution function (e-PDF) in the TEM. This technique allows the study of materials at the local environment (nm scale) using collected (ED) patterns. We will show how e-PDF has been recently applied to study nanoparticles and amorphous materials.
The use of Precession Diffraction for in situ Cross-correlative microscopy
Prof. Greg Thomson, University of Alabama
In this webinar, Prof Greg Thomson from the University of Alabama will present his work with Cross correlative PED. With the ever growing importance for understanding nanoscale phenomena, the ability to quantify the material structure at the appropriate length scale is important in ultimately elucidating underlying mechanisms. Scanning Precession (SPED) electron diffraction in quantifying the green texture and grain boundary character is correlated to 2 two examples: in the first case study, its impact in understanding nanoscale deformation is described. Here, a multilayered crystalline and amorphous multilayer stack is subjected to Nano-indentation using SPED the mechanical induced grain growth in the crystalline layers is capture along with grain rotation. Using Finite element modeling, the loading response in the nanostructure is then able to be directly linked to the scanning PED outcomes. In the second example the use of SPED is cross- correlated to atom probe tips to reveal the grain boundary specificity of solute segregatio enabling verification and validation of atomistic computational models.
Structural Characterization in TEM by Electron Pair Distribution function (e-PDF)
Dr. Partha Das Application Scientist NanoMEGAS Belgium
Understanding and possible prediction of material physical properties depends upon the knowledge of the atomic structure. Study of nanocrystalline or amorphous materials can be optimally performed with techniques like Pair Distribution Function (PDF) that is used to understand local atomic arrangement by using X-Ray, Neutron and Electron sources. Electron Diffraction related PDF (e- PDF) in Transmission Electron Microscope (TEM) has the advantage over X- Ray or Neutron PDF technique that allows studying materials in local environment (nm scale instead of micron scale) by collecting (ED) patterns in short time (ms instead of hours with conventional X-Ray Au or Mo sources). In this webinar we will show how e-PDF has been recently applied to study nanoparticles and amorphous materials and it will also be demonstrated that e-PDF results matches well with equivalent X-Ray PDF.
Structural Characterization in TEM by 3D Electron Diffraction / Micro-ED
Dr. Partha Das Application Scientist NanoMEGAS Belgium
In recent years there has been a huge interest in characterization for various materials where more than 300 structures have been solved (minerals, zeolites, MOFS, aperiodic crystals, archaeological artefacts, functional materials, organic pharmaceuticals, proteins etc.) using 3D Electron Diffraction from nanometer size crystals in TEM. The principle of acquiring TEM 3D-ED data consists of focusing the electron beam on a nanometer size crystal (50-500 nm), while sampling thereciprocal/diffraction space in small steps using beam precession or continuous crystal rotation (with or without beam PED, technique known as 3D Electron Diffraction Tomography/Micro-ED). ED intensities can be registered using CCD cameras or ultra- sensitive pixelated detectors. Acquired 3D-ED data can be used to determine ab-initio crystal unit cell, space group and atomic positions. Further dynamical refinement can also be performed using PED to detect H atoms, refine occupancies an improve reliability of the structural model down to 1-3 pm accuracy. In this webinar various examples will be shown how 3D-ED method has been applied successfully to solve structures of a big variety of nanocrystalline materials.
