Fri, 02/24/2012 - 00:00 | Atlanta, GA
In 1982, Dan Shechtman made a discovery that would turn 70 years of crystallography on its head. As years went by and he fought to convince scientists around the world of his find, the person who emerged as his chief antagonist happened to be perhaps the most influential chemist in history, with two Nobel Prizes on his shelf.
Finally, in 2011, Shechtman earned the ultimate vindication, with a Nobel of his own.
In a standing-room-only lecture on Feb. 23 at Georgia Tech, Shechtman told the story of his 1982 discovery of quasi-periodic crystals, which went against everything that was known about the structure of crystals and resulted—30 years and many scientific battles later—in his being awarded the 2011 Nobel Prize in Chemistry.
Shechtman, who is Philip Tobias Professor of Materials Science at the Technion – Israel Institute of Technology (click here for full bio and abstract), laid the groundwork for his audience by explaining that modern crystallography began in 1912 with the seminal work of German physicist Max von Laue. Von Laue established the three basic principles of crystalline structure: order, periodicity and rotational symmetry. Shechtman then carefully defined each term, concluding with the universally accepted—until Shechtman’s discovery—definition of crystals as “solids composed of atoms arranged in a pattern that is periodic and in three dimensions,” and that the rotational symmetry of crystals could be one-, two-, three-, four- or six-fold—never five-fold and never more than six.
But in 1982 as a young faculty member at the Technion, Shechtman one day discovered an apparent tenfold crystalline rotational symmetry in a crystal composed of aluminum and manganese, and further found that the crystal’s structure was not periodic but quasi-periodic. To drive home his own surprise at the time, Shechtman displayed an image of the actual page from his 30-year-old notebook, with “10fold!!!” written clearly by a set of notations.
“At the end of the day, I knew this was something new and exciting,” he said, further adding that years earlier in graduate school he’d been given a test in which he had to prove that such rotational symmetry in crystals was impossible. “And I did it. I passed the test. I would not be here [talking to you] if I hadn’t.”
So began a decade-long odyssey of Shechtman persisting to convince more and more scientists of his findings. First it was his group research leader at the U.S. National Bureau of Standards (now called the National Institute of Standards and Technology), who called Shechtman a “disgrace” and kicked him out of the group. Then it was members of the International Union of Crystallography (IUCr), who rejected the study due to Shechtman’s having used an electron microscope; the IUCr insisted that legitimate studies of crystalline diffraction used X-rays, not electron beams.
Finally it came down to one man: Linus Pauling, winner of Nobel Prizes in two different fields and one of the greatest scientists of the 20th century. Pauling rejected the idea of quasi-periodic crystals right up until his death in 1994, and envious colleagues used Pauling’s objections to argue against Shechtman’s academic promotions, even as crystallographers around the world came to accept his work.
In the end, of course, the discovery was accepted, and Shechtman proudly pointed to a new definition of crystals, adopted in 1991, that acknowledges “aperiodic crystals … in which three-dimensional lattice periodicity can be considered to be absent.”
“It is a soft, humble definition,” he said. “And a humble scientist is a good scientist.”
Shechtman’s visit was sponsored by the Georgia Tech colleges of Computing, Science and Engineering, as well as the Georgia Tech Executive Vice President for Research, the Georgia Tech Research Institute, the Georgia Tech Institute for Leadership and Entrepreneurship, the American-Israel Chamber of Commerce-Southeast Region, the American-Israel Educational Institute, and Given Imaging.