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Materials Science at Oregon State University

Convergent Beam Electron Diffraction - An Overview of a Misunderstood Technique

Date: Thursday, May 17th
Presenter: Dr. John Mansfield, Associate Director, Electron Microbeam Analysis Laboratory (EMAL), Department of Materials Science and Engineering, University of Michigan (Ann Arbor)

Abstract


Convergent beam electron diffraction, usually referred to by its acronym, CBED, but pronounced as a word, hence SEEBED, is one of the most powerful techniques available to the transmission electron microscopist.

Although first used by Kossel and Mollenstadt in 1939, it took the development of scanning transmission electron microscopes in the late 1960s and early 1970s to really allow the technique to flourish. Leading developers of the technique include Lehmpfuhl, Goodman, Moddie, Gjonnes, Watanabe, Buxton, Steeds, Eades, Tanaka and Terauchi. CBED can be used to perform crystallographic analysis of materials down to the nanometer length scale and can reveal the full three dimensional symmetry of a crystal. Users new to the technique are often frustrated, however, as their patterns are not the same as the beautiful, high symmetry, detailed patterns seen in the literature. This presentation will introduce CBED and outline its applications and show how it can use useful even when the patterns are far from perfect.

Biography
John Mansfield is an Associate Research Scientist in Materials Science and Engineering and the Associate Director and Manager of the North Campus Electron Microbeam Analysis Laboratory (EMAL), a University-wide user facility for the structural and chemical analysis of materials at nanometer length scales.

Mansfield received his B.Sc. in Chemical Physics at the University of Bristol, Bristol, UK in 1979. He continued his studies at Bristol receiving his M.Sc. in the Physics of Materials in 1980 and his Ph.D. in Physics in 1983. He was a post-doctoral researcher at Argonne National Laboratory between 1984 and 1986 and a visiting scientist at the Microelectronics Center of North Carolina from 1986 to 1987. In 1987, Mansfield joined the faculty of the Department of Materials Science and Engineering and became manager of the North Campus EMAL and has been at the University of Michigan and responsible for the laboratories and offices of the North Campus Electron Microbeam Analysis Laboratory (EMAL) for the past 20 years.

Since his arrival at the University of Michigan, Mansfield has been committed to the development of the North Campus EMAL into a world class state-of-the-art characterization facility that not only serves the campus community, but also supports a range of local industries and sister academic institutions in southeastern Michigan, northern Ohio and southwestern Ontario.

Mansfield currently serves as Editor of Microscopy and Microanalysis, and President of the Microanalysis Society.