Israeli scientist wins Nobel for Chemistry

Prof. Daniel Shechtman, 70, a professor of materials science at Technion-Israel Institute of Technology

Israeli scientist wins Nobel for Chemistry

The 2011 Nobel prize for Chemistry has been won by Daniel Shechtman, a professor of materials science at Technion-Israel Institute of Technology and at Iowa State University as well as a researcher at the Department of Energy’s Ames Laboratory.

Recent Nobel prizes have generally split credit for scientific advances among two or three people but this year’s chemistry prize and accompanying 10 million Swedish kronor ($1.4 million) went to a single scientist: 70 years-old Dr. Shechtman

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

Random jumble

Such 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 it was thought impossible in the packing of atoms.

Yet Dr. Shechtman discovered the same type of structure in a mix of aluminum and manganese.

During a sabbatical in the United States 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.

“10 Fold???”

Yet when he examined his metal with an electron microscope, Dr. Shechtman found that the atoms were not random.

His notebook recorded the exact date: April 8, 1982.

Scientists believed that crystals in materials all contained repeating patterns. For example, a square lattice has fourfold 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 Dr. Shechtman bounced off his aluminum-manganese alloy formed a pattern that indicated ten-fold symmetry.

Dr. Shechtman himself could not quite believe it.

He wrote in his notebook, “10 Fold???”

“Discrete diffraction diagram”

While a periodic lattice could not produce that pattern, a quasicrystal could.
It took years for Dr. Shechtman to persuade others.

During the announcement, the Nobel committee noted that one colleague said, “Go away, Danny” and that he was even asked to leave the research group.

Many scientists, notably Linus Pauling, the Nobel-winning giant of chemistry, argued vehemently that Dr. Shechtman’s data could be explained by defects within ordinary periodic crystals.

“That must have been intimidating,” said Nancy 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 realise he was right.”

Even the definition of crystal had to be redefined. Previously, a crystal had “a regularly ordered, repeating three-dimensional pattern,” according to the International Union of Crystallography.

The new definition, adopted in 1992, states that a crystal is simply a solid with a “discrete diffraction diagram” — that is, something that produces patterns like Dr. Shechtman saw.

That leaves the door open for yet more different kinds of crystals in the future.

Quasicrystals have since been found in many other materials, including a naturally occurring mineral from a Russian river. Materials scientists have been exploring quasicrystals because of their distinct properties.

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.

NP/Uche Iheanacho/Hajia Sani