INTERNATIONAL

Chemistry Nobel for Dan Shechtman

An Israeli scientist won this year's Nobel Prize in Chemistry for discovering quasicrystals, a material in which atoms were packed together in a well-defined pattern that never repeats.

Recent Nobel prizes have generally split credit for scientific advances among two or three people, but this year's chemistry prize and the accompanying 10 million Swedish kronor ($1.4 million) went to a single scientist: Dan Shechtman (70), a professor of materials science at Technion-Israel Institute of Technology in Haifa, Israel. Prof. Shechtman is also a professor at Iowa State University and a researcher at the U.S. Department of Energy's Ames Laboratory.

The citation from the Royal Swedish Academy of Sciences states simply, “for the discovery of quasicrystals.”

Regular but non-repeating patterns, defined by precise rules, have been known in mathematics since antiquity, and medieval Islamic artists made decorative, non-repeating tile mosaics, but the phenomenon was thought impossible in the packing of atoms.

Yet Prof. Shechtman discovered the same type of structure in a mixture of aluminium and manganese. During a sabbatical in Maryland at the National Bureau of Standards, now known as the National Institute of Standards and Technology, he took a molten glob of the metals and chilled it rapidly. The expectation was that the atoms would have been a random jumble, like glass. Yet when he examined his metal with an electron microscope, Prof. Shechtman found that the atoms were not random.

His notebook recorded the date: April 8, 1982.

Scientists believed that crystals in materials all contained repeating patterns. For example, a square lattice has four-fold symmetry. Rotate it by 90 degrees, and it looks identical. A repeating lattice with five-fold symmetry, however, is impossible. On that morning in 1982, the electrons Prof. Shechtman bounced off his aluminium-manganese alloy formed a pattern that indicated ten-fold symmetry. He could not quite believe it. He wrote in his notebook, “10 Fold???”

While a periodic lattice could not produce that pattern, a quasicrystal could.

Opposition

It took years for Prof. Shechtman to convince others.

During the announcement, the Nobel committee noted that one colleague initially said, “Go away, Danny,” because he thought there was a simpler explanation for what Prof. Shechtman had observed. Many scientists notably Linus Pauling, the Nobel-winning giant of chemistry argued that Prof. Shechtman's data could be explained by “twinning,” where two ordinary periodic crystals are fused together at an angle.

“That must have been intimidating,” said Nancy B. Jackson, president of the American Chemical Society. “When he first discovered these materials, nobody thought they could exist. It was one of these great scientific stories that his fellow scientists thought was impossible, but through time, people came to realize he was right.”

Quasicrystals have so far had a modest impact in the everyday world. For example, one kind of highly resilient steel, consisting of hard steel quasicrystals embedded within softer steel, is now used in razor blades and thin needles for eye surgery.

“The applications haven't panned out,” said Patricia A. Thiel, a colleague of Prof. Shechtman's at Iowa State and Ames Laboratory who also studies quasicrystals. “But they revolutionised our understanding of how atoms arrange themselves in solids. It was a scientific revolution.”

Israeli leaders expressed delight and pride at the 10th Nobel Prize won by a citizen of Israel, which has a population of less than eight million. Two years ago, Ada E. Yonath of the Weizmann Institute of Science in Rehovot, Israel, shared the award for chemistry as well.

Shimon Peres, Israel's President, spoke by telephone with Prof. Shechtman at a news conference in Haifa and said, “Professor Shechtman, you today brought an enormous gift to the State of Israel, truly.”

Prime Minister Benjamin Netanyahu also called and told him, “Every Israeli is happy today, and every Jew in the world is proud.” — New York Times News Service