Dr. Dan Shechtman, winner of the 2011 Nobel Prize in Chemistry, will deliver a Distinguished Lecture, "Quasi-Periodic Materials: Crystal Redefined," in the Georgia Tech College of Management's LeCraw Auditorium on Thursday, Feb. 23, at 5:30 p.m. Shechtman is Philip Tobias Professor of Materials Science at the Technion – Israel Institute of Technology, an associate of the U.S Department. of Energy's Ames Laboratory, and professor of materials science at Iowa State University.

There will be refreshments served beginning at 5 p.m.

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Abstract

Crystallography has been one of the mature sciences.  Over the years, the modern science of crystallography that started by experimenting with x-ray diffraction from crystals in 1912, has developed a major paradigm – that all crystals are ordered and periodic.  In-deed, this was the basis for the definition of “crystal” in textbooks of crystallography and x-ray diffraction. Based upon a vast number of experimental data, constantly improving research tools, and deepening theoretical understanding of the structure of crystalline materials no revolution was anticipated in our understanding the atomic order of solids.

However, such revolution did happen with the discovery of the Icosahedral phase, the first quasi-periodic crystal (QC) in 1982, and its announcement in 1984 [1, 2].  QCs are ordered materials, but their atomic order is quasiperiodic rather than periodic, enabling formation of crystal symmetries, such as icosahedral symmetry, which cannot exist in peri-odic materials.  The discovery created deep cracks in this paradigm, but the acceptance by the crystallographers' community of the new class of ordered crystals did not happen in one day.  In fact it took almost a decade for QC order to be accepted by most crystallographers. The official stamp of approval came in a form of a new definition of “Crystal” by the International Union of Crystallographers. The paradigm that all crystals are periodic has thus been changed. It is clear now that although most crystals are ordered and periodic, a good number of them are ordered and quasi-periodic.

While believers and nonbelievers were debating, a large volume of experimental and the-oretical studies was published, a result of a relentless effort of many groups around the world. Quasi-periodic materials have developed into an exciting interdisciplinary science. 

This talk will outline the discovery of QCs and discuss their structure as well as some of their properties and uses.

Bio

After receiving his doctorate from the Technion in Haifa, Israel, Danny Shechtman was an NRC fellow at the Aerospace Research Laboratories of Wright Patterson AFB, Ohio, where for three years he studied the microstructure and physical metallurgy of titanium aluminides. In 1975 he joined the Department of Materials Engineering at Technion, where he is currently a Distinguished Professor. Between 1981 and 2004 he was visited Johns Hopkins University several times on sabbatical as part of a joint program with NBS-NIST. During this period he discovered by TEM the Icosahedral Phase, which opened the new science of quasiperiodic crystals, and performed research on other subjects. As of 2004 he is also a Professor at MSE and Ames Lab at Iowa State University. His current research efforts center on developing strong and ductile magnesium alloys for a variety of applications and deformation mechanisms in B2 intermetallics.

Shechtman is a member of several academies, including the National Academy of Engineering, and he is an honorary member of professional societies around the globe. He has been awarded many prizes, including the Wolf Prize in Physics, the Gregori Aminoff Prize of the Royal Swedish Academy of Sciences, the EMRS award and the 2011 Nobel Prize in Chemistry.