UW Today

July 25, 2011

Materials scientist John Cahn awarded international Kyoto Prize

News and Information

John Cahn

John Cahn

A Kyoto Prize was recently awarded to John Cahn, a UW affiliate professor in the departments of physics and materials science & engineering.

The Inamori Foundation, established by the president of Kyocera Corp., initiated the prizes in 1984 “to honor those who have contributed significantly to the scientific, cultural, and spiritual betterment of mankind.” It is Japans equivalent of the Nobel Prize, said Japanese native Fumio Ohuchi, a UW materials science and engineering professor and colleague of Cahns.

The Kyoto Prizes are awarded annually in three categories: advanced technology, basic sciences, and arts and philosophy. Each honoree is presented with a gold medal and an award of 50 million yen, about $615,000.

“Total amazement,” Cahn said of his reaction to learning the news. “Its a great honor, and a little surprising to come at my age,” added the 83-year-old.

The selection committee noted Cahns contributions to understanding the behavior of mixed materials and how they tend to separate at the microscale.

“The prize is given for an equation which I wrote down in 1961,” Cahn said.

He modified the standard diffusion equation that predicts how materials tend to clump together and evolve over time. It has proven useful for developing new alloys, mixtures of two or more metals that are commonly used in manufacturing.

British scientist John Hilliard and his students at Northwestern University did the experiments to prove that Cahns theoretical work was correct and expanded its applicability; it is now known as the Cahn-Hilliard equation.

The work has been cited more than 10,000 times, Cahn said, in fields ranging from population dynamics to clumping in the early universe.

“Its entered so many fields, because this is something that occurs quite commonly, and until this modification was introduced there was no way of treating this behavior mathematically to make any predictions.”

Most recently, said Ohuchi, the equation is being used at the UW and other research institutions to develop new solar cells. An emerging technology uses two different types of plastic, instead of silicon, to trap solar energy and feed it to the electrical grid.

“If you try to combine these two materials in an artificial way its very time consuming, almost impossible in terms of time and also economics,” Ohuchi said. Instead, materials scientists use Cahns equation to create conditions where the two plastics mix in the right way.

“So although his original contribution was for metals, half a century later people are using the identical concept and applying it to organic solar cells,” Ohuchi said.

Cahn earned his bachelors degree in chemistry at the University of Michigan and his doctorate in physical chemistry in 1953 at the University of California, Berkeley. He spent two years as a junior faculty member at the University of Chicago before joining General Electric for 10 years. From 1964 to 1978 he was a professor of materials science at the Massachusetts Institute of Technology.

In the late 1970s Cahn took a two-year leave of absence from MIT to work at the National Institute of Standards and Technology in Gaithersburg, Md. He liked it so much he accepted a permanent position in the metallurgy division of the Material Measurement Laboratory, where he is currently an emeritus senior fellow.

Cahn joined the UWs department of materials science & engineering as an affiliate professor in 1984 at the invitation of late professor Ryoichi Kikuchi, and then joined the UWs physics department at the invitation of late professor Greg Dash. Cahn moved to Seattle in 2006 to be closer to two sons and four grandchildren. He shares an office in the Physics & Astronomy Building, currently serves on a thesis committee and is completing some research on metallic glass.

“Now its dabbling,” Cahn says of his research. “Its very relaxed, doing things Im interested in.”

Cahn will attend a prize ceremony in Kyoto in November and another ceremony in San Diego in March.

Cahn is a member of the American Academy of Arts and Sciences, the Japan Institute of Metals, the National Academy of Engineering and the National Academy of Sciences.

This years Kyoto Prize for basic sciences was awarded to the Russian and German astrophysicist Rashid Sunyaev. The arts and philosophy prize went to Japanese Kabuki actor Tamasaburo Bando.