Electron Backscatter Diffraction (EBSD)

Electron Backscatter Diffraction (EBSD)

Electron Backscatter Diffraction (EBSD) is a technique used for crystal structure analysis using the diffraction patterns of an incident electron beam, focused on the sample from a scanning electron microscope (SEM). The diffracted electrons impinge on a phosphor screen placed near the sample, where they generate visible lines called Electron Backscatter Diffraction (EBSD) patterns or Kikuchi Diffraction Bands. The technique involves placing the crystalline sample in the SEM, at a suitable angle to the incident electron beam, along with the phosphor screen located close to the sample to detect the diffraction patterns. A digital camera captures the EBSD patterns which are processed by a computer. Since the diffraction patterns represent the projections of lattice planes in the crystal onto the flat phosphor screen, they provide information on crystal orientation, allow differentiation between different crystalline phases, indicate grain boundaries, and local crystal defects. Individual grains, aggregates or multiple crystal phases near the surface of the sample can be investigated. In fact, thousands of individual grains and individual spots can be scanned using EBSD, in a few hours. It is possible to obtain images with a resolution level of several microns.

EBSD with the use of SEM is an important tool for collecting crystallographic information routinely on a range of natural and synthetic crystalline materials like metals, ceramics, rocks, ice and semiconductors.

Common Uses of Electron Backscatter Diffraction (EBSD)

• Measurements of Grain size, Grain boundary characterization, local and global texture
• Crystalline boundary characterization
• Substructure analysis
• Phase identification and distributions
• Phase transformation studies
• Fracture analysis

Advantages of Electron Backscatter Diffraction (EBSD)

• Once samples are prepared, it is a rapid and reliable method of crystallographic analysis
• The spatial resolution is of the order of several microns

Limitations of Electron Backscatter Diffraction (EBSD)

• Since the technique analyses surface crystals, mechanical grinding and polishing of samples (such as microprobe samples) can damage crystal lattices near the surface. Hence chemical polishing is also needed.
• When working with insulating materials like ceramics or minerals, conductive coatings may be needed, which affects the analysis.

Industrial Applications of Electron Backscatter Diffraction (EBSD)

• Fabrication related microstructure studies of metals and alloys, intermetallic phases, inclusions, precipitates
• Research and development in microelectronics, thin films, solar cells, ceramics, semiconductors, superconductors