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Characterization anomaly leads to Nobel Prize

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ImageWhen Danny Shechtman first saw the diffraction pattern with 10 points in 1982, he had no idea the ridicule he would face because of it, or that it would eventually lead to complete vindication in the form of the 2011 Nobel Prize in chemistry.  As a scientist characterizing a new aluminum-manganese alloy, he simply knew he was seeing something unique that didn’t fit with the accepted rules for crystalline structure. And he believed what his eyes were seeing.

“I was working alone in the electron microscope lab (as a guest researcher at what was then the National Bureau of Standards) studying this new material and right away, it looked very strange to me,” Shechtman says. “So I took an electron diffraction and I counted 10 spots and said, ‘No, it cannot be!’”

“I counted again another way and it was still 10 spots,” he continues.  “I thought, ‘10-fold symmetry … this is an amazing thing! I must share it with somebody.’ So I went out in the corridor, but there was no one else around, so I went back and spent the rest of the day performing experiments.”

His initial thought was that the pattern he was seeing was the result of a phenomenon known as twinning, where two rows of atoms form a mirror image with a boundary in between them.  But as he looked, he could find no evidence of twins. In rotating the crystal, he also discovered the material actually had an equally impossible five-fold rotational symmetry, not 10-fold as he first suspected, and he knew he was seeing something new and unexplained.

ImageShechtman’s discovery, which contradicted conventional wisdom, was discounted as “outrageous” and he was ridiculed by even his colleagues, including being dismissed from his research group. But he continued to study the material and in November 1984, with support from physicist John Cahn, materials scientist Ian Blech, and crystallographer Denis Gratias, published his data in an article, “Metallic Phase with Long-Range Orientational Order and No Translational Symmetry,” in Physical Review Letters.

The article took Shechtman’s discovery, and criticism of it, to a whole new level. One of the harshest opponents was two-time Nobel Prize winner Linus Pauling.

“He was a highly respected scientist and the idol of the American Chemical Society and to his last day, he would stand on those platforms and declare, ‘Danny Shechtman is talking nonsense,” Shechtman recalls. “Pauling would often say, ‘There is no such thing as quasicrystals, only quasi-scientists.’”

However, Shechtman’s article also began to win over supporters who were able to replicate his results. Theoretical support for quasicrystals soon came about from an aperiodic mosaic developed by British mathematician Roger Penrose.  By 1992, the International Union of Crystallography altered its definition of a crystal to “any solid having an essentially discrete diffraction diagram,” where it had previously suggested crystals had to be periodic in nature.

Shechtman’s selection for the 2011 Nobel Prize in chemistry is the ultimate vindication for the years spent defending his discovery.  His unwavering belief in his original findings holds an important lesson for anyone in the field of science or the broader scope of human endeavor.

“If you’re a scientist and believe in your results, then fight for it … fight for the truth,” he says. “Listen to others, but fight for what you believe in.”

ImageAmes Laboratory senior scientist Pat Thiel, who was instrumental in bringing Shechtman to Ames Lab and Iowa State University, marvels at Shechtman’s tenacity and his ability to stay cordial and respectful with even his most vocal critics.

“The stories of his life and career have been inspirational to me, especially the controversy with Linus Pauling and the fact that they remained on cordial terms even as they battled professionally,” says Thiel.  “In fact they met several times for dinner at conferences, and Danny once made a special visit to Linus to try to convince him about quasicrystals.”

“Most people would have become bitter and incensed,” Thiel continues, “but Danny didn’t and in fact, he did not even take the controversy as a personal affront. To remain on civil and respectful terms with people, even in the face of strong disagreements, is one of my professional aspirations and also one of the most remarkable aspects of Danny’s achievement.”

ImageFor Paul Canfield, Ames Lab senior physicist, Shechtman’s discovery has been an ongoing subject of study throughout Canfield’s career.

“Danny’s discovery was profound,” Canfield says. “Quasicrystals offered a mysterious waystation between crystalline and amorphous.  Just how this new form of order affects the physical properties of quasicrystals is something I keep coming back to over the decades.”
Canfield’s first publication as a graduate student at UCLA was the measurement of meltspun quasicrystalline ribbons.  At Ames Lab, he was able to grow some of the first faceted single-grain, rare-earth-magnesium-zinc quasicrystals, a perfect blend of Ames Lab’s expertise in rare earths and quasicrystals.

“With (Ames Lab senior physicist) Alan Goldman we were able to determine that rare earths, ordered in a quasicrystal, act in a manner similar to a glass, but a highly ordered one,” he says. “With our discovery that solution growth was an excellent way to grow these complex materials, we expanded the number of systems we studied and actually taught the world how to grow these compounds.”

“It is my firm belief that if we look carefully enough and grow carefully enough, there will be many examples of quasicrystals lurking in binary and ternary phase diagrams,” Canfield concludes. “The real big remaining question is to understand why a material forms a quasicrystal rather than a crystalline phase.”

ImageAlan Goldman agrees that Shechtman’s findings have ultimately changed the way researchers think about the composition of matter.

“Danny’s discovery really opened a new frontier in materials research and certainly had a very strong impact on my own career,” Goldman says. “Very soon after his discovery, I began to study the structure and properties of quasicrystals  at Brookhaven National Laboratory. When I came to Ames in 1988, I continued that work with other Ames Lab scientists such as Pat Thiel, Paul Canfield, Matt Kramer, Bill McCallum and Tom Lograsso,” he continues, “and I can only say that it has been a ‘fantastic journey’ that epitomizes the Ames Lab’s interdisciplinary approach to science.”


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far left: A holmium-magnesium-zinc (Ho-Mg-Zn) quasicrystal, grown by Ames Laboratory senior physicist Paul Canfield, that clearly shows five-fold (pentagonal) symmetry.

left: An X-ray diffraction image captured by Alan Goldman that shows the “10-spots” that Shechtman first noticed through his transmission electron microscope.