Electron Backscatter Diffraction (EBSD)

Bowdoin Geology: Professor Rachel Beane in the LabBowdoin College's Electron Backscatter Diffraction (EBSD) system purchased with funds awarded through the NSF Major Research Instrumentation program (proposal 0320871 funded to Rachel Beane). The EBSD system, by HKL Technology Inc., includes a Nordlys II EBSD Detector, forescatter detectors and software for orientation mapping (stage and beam control), texture determination, and phase identification (using the American Mineralogist Geological Phase database). The system is attached to a LEO 1450VP SEM (variable pressure scanning electron microscope) with an EDAX energy dispersive spectrometer (EDS) for mineral chemistry.

What is EBSD?

Click image to enlarge
Kink banding and undulatory extinction in kyanite from the UHP Kokchetav Massif, Kazakhstan
Bowdoin Geology: Kink banding and undulatory extinction in kyanite from the UHP Kokchetav Massif, Kazakhstan

In geology, EBSD is a powerful tool for the observation and analysis of microstructures and for phase identification. The EBSD system uses backscattered electrons (BSE) emitted from a specimen in a SEM to form a diffraction pattern that is imaged on a phosphor screen. Analysis of the diffraction pattern allows identification of the phase and its crystal lattice orientation. The scanning and mapping capabilities of the system permit rapid acquisition of data, from polished rock thin sections, at sub-micron resolutions. Among other uses, these data may be applied to evaluate crystallographic preferred orientations (CPO) of mineral fabrics, and to examine misorientation axes and angles that may signify processes such as subgrain development and dislocation creep.

Invitation for Collaboration

Researchers interested in applying EBSD methods to textural problems in rocks are encouraged to contact Professor Rachel Beane for possible collaborations.

Publications from EBSD lab

  • Bowdoin Geology: KikuchiBeane, R.J. and Field, C., 2007. Kyanite deformation in whiteschist of the UHPM Kokchetav Massif, Kazakhstan. Journal of Metamorphic Geology v. 25, p. 117-128.
  • Hawkins, A.T., Selverstone, J., Brearley, A.J., Beane, R.J., Carlson, W.D. and Ketcham, R., 2007. Origin and mechanical significance of honeycomb garnets in high-pressure metasedimentary rocks from the Tauern Window, Eastern Alps. Journal of Metamorphic Geology v 25, p. 565-583.
  • Beane, R. J., 2004. Using the scanning electron microscope for discovery based learning in undergraduate courses. Journal of Geoscience Education, v. 52, p. 250-253.
  • Msall, M.E., Dietsche, W., Beane, R., Wichard, R. and Carpenter, J.*, 2004. Examination of an unusual grain boundary in CaF2. Physica Status Solidi (c), v. 1, no. 11, p. 2983-2986.
  • Beane, R. J. and Prior, D.J. in revision. Crystallographic orientation evidence for the formation of atoll garnet in eclogite. Geology.

Conference Abstracts from EBSD lab

  • Bowdoin Geology: Simulation Naus-Thijssen, F., Johnson, S., and Beane, R., 2007. Crenulation cleavage development and its rheological implications. Geological Society of America, Abstracts with Programs, v. 39, p.78.
  • Rodriguez, A.* and Beane, R.J., 2006. Pigeonite Microstructures in Martian Meteorite EETA79001. Geological Society of America, Abstracts with Programs, v. 38, No. 7, p.77.
  • Beaulieu, J., McFadden, R. and Fayon, A., 2007. Grain-scale deformation and kinematics along a strain gradient, Pioneer Metamorphic Core Complex, Idaho. Geological Society of America, Abstracts with Programs, v. 39, p.74.
  • Naus-Thijssen, F., Johnson, S., and Beane, R.J., 2006. Chemical and Mechanical Development of Crenulation Cleavage. Knowledge Based Materials, Marie Curie Summer School on Polyphase and Composite Materials, Älvdalen, Sweden.
  • Rodriguez, A.* and Beane, R.J., 2006. Pigeonite Microstructures in Martian Meteorite EETA79001. Maine Space Grant Consortium, Annual Meeting, Boothbay, Maine.
  • Beane, R.J. and Field, C.F., 2005. Kyanite deformation in whiteschist of the UHPM Kokchetav Massif, Kazakhstan. Eos Trans. AGU, 86(52), Fall Meet. Suppl., Abstract V43A-1549.
  • Hawkins, A., Selverstone, J., Brearley, A. and Beane, R., 2005. Fishnet and atoll garnets from the Tauern Window, Eastern Alps: Conditions and Mechanisms of Formation. Geological Society of America, Abstracts with Programs,v. 37, p. 226.
  • Msall, M.E., Dietsche, W., Beane, R., Wichard, R. and Carpenter, J*, 2004. Examination of an unusual grain boundary in CaF2. The 11th International Conference on Phonon Scattering in Condensed Matter (Phonons2004), St. Petersburg, Russia.
  • Beane, R. J. and Prior, D. J , 2002. Using EBSD analysis to interpret garnet microstructures. Geological Society of America, Abstracts with Programs, v. 34, p. 9.

Kibbe Science Symposium

Saturday, April 16, 2005
Microstructure Analysis Using Electron Backscatter Diffraction link will open a PDF - Portable Document Format

Methods

The typical methods this lab uses for collection and processing of EBSD data follow. Specific projects will vary from these methods.

Electron backscatter diffraction (EBSD) analyses are conducted at Bowdoin College on a LEO 1450VP SEM outfitted with an HKL Nordlys II detector and Channel 5 software. Samples are prepared by taking standard polished thin sections weighted with halved brass rods (M. Cheadle, personal communication) and polishing an additional six hours in a non-crystallizing colloidal silica suspension on a Buehler Vibromet2 vibratory polisher (SYTON method of Fynn and Powell, 1979). Thin sections are not carbon coated; charging is minimized by using a chamber pressure of 10-15 Pa, combined with the 70° tilt. Operating parameters for collecting EBSD patterns are an accelerating voltage of 20kV, working distance of 25 mm, and probe current of 2.2nA. Channel 5 acquisition and indexing settings vary by phase, but typical values are 2x2 or 4x4 binning, high gain, Hough resolution=75, 7 bands, and 80 reflectors. Mean angular deviations between the detected Kikuchi bands and the simulations are less than 1.3 degrees (and often less than 0.8 degrees). Data are post-processed by removing wild spikes, removing observed systematic misindexing, and by extrapolating zero solutions based on 4 neighbors (if required).

Oxford Instruments (formerly HKL Technology) (instrument manufacturer)

Bowdoin SEM webpage

These web pages and material are based upon work supported by the National Science Foundation under Grant Nos. 9951390 and 0320871 to R. Beane. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.