Nuclear Science and Engineering

IVEM: TEM Capabilities

Transmission Electron Microscopy Capabilities

The IVEM interfaces with an ion beamline incident from above at 30° to the electron beam, allowing in situ irradiations during observation under controlled sample and diffracting conditions.

TEM
  • Hitachi-9000 with side-entry sample stages, LaB6 filament
  • Range of electron energies, 100-300 keV
  • A range of total electron currents directly measured with Faraday cup stage
  • Point resolution, 0.25 nm at 300 keV
  • Excellent mechanical stability of sample at elevated temperatures during in situ irradiation, resolving defects to 1 nm
  • Oil-free vacuum of 5x10-8 Torr at sample
Camera
  • GATAN OneView digital camera with full resolution images of 4kx4k pixels and 16 bit dynamic range
  • In situ movies in two modes:
    • ANL system with data bar, 1Kx1K and 10 frames per second (fps).
    • GATAN in situ mode (without data bar) up to 200 fps at 1Kx1K resolution with ​“look back” feature.
  • Data file sizes:
    • Single image at full resolution, 66 MB.
    • ANL movie with data bar, 2 GB in 10 minutes.
    • GATAN in situ movie at 1Kx1K resolution and 200 fps, 100 GB per minute.

Computer Vision Assisted Video Analysis

  • Automated analysis of irradiation-induced voids by a semantic segmentation model.
  • Individual voids can be identified and measured frame-by-frame to reveal the dynamics of microstructural evolution in materials under irradiation.   

Sample Stages for in situ TEM

  • High temperature (20-850°C, ±3°C), double tilt (±40°, ±20°). No epoxy above 300°C, no Cu grids above 600°C.
  • High temperature (20-1100°C), single tilt (±40°). Same restrictions as above.
  • Low temperature (20-300°K), double tilt (±40°, ±20°).
  • Triple axes, double tilt (±40°, ±10°) rotate (180°), room temperature.
  • Straining, high temperature (20-400°C), single tilt (±40°). No epoxy above 300°C.
  • Straining, low temperature (100-400°K), single tilt (±40°). With permission.
  • Environmental cell TEM holder (700°C) with an oxidizing reaction chamber (300°C), single tilt (±40°).

In Situ Capabilities

  • Continuous recording of image with in situ specimen conditions of ion dose, temperature and strain.
  • Sample stages for in situ irradiation include control of sample temperature to ±3C° over a range of 20 K to 1100°C.
  • Sample straining stage allows in situ experiments with samples under irradiation and stress at temperatures up to 400°C.
  • Three-rotation-axes sample stage (double-tilt rotate) allows a relatively easy tomography measurement (±40° tilting) for imaging of defects and microstructure in 3D maintaining constant diffraction conditions.
Irradiation defects in Mo in 3D

Movie of interstitial dislocation loops formed in Mo by 1 MeV Kr ion irradiation at 80°C, rotating in 3D and produced by reconstruction of tomographic data while maintaining constant diffraction condition.



Meimei Li, M.A. Kirk, P.M. Baldo, Donghua Xu, and B. D. Wirth, ​“Study of Defect Evolution by TEM with in situ Ion Irradiation and Coordinated Modelling,” Phil Mag. 92 (2012) 2048.