Conductive ceramics grow in a solution - ability to make highly conductive ceramic, called a defect chemistry superlattice, from layers of thallium oxide - Brief Article

Science News, June 18, 1994 by Richard Lipkin

Highly conductive ceramics, especially the superconducting copper oxide variety are extremely hard to make.

Typically, scientists painstakingly deposit elements atom by atom on a thin film inside a multi-million-dollar vacuum chamber, then bake the film in a high-temperature kiln--an expensive, tedious, and labor-intensive process.

Now, a group of researchers reports an entirely different approach. In the June 10 Science, Jay A. Switzer, a chemist at the University of Missouri at Rolla, and his colleagues describe "growing" highly conductive ceramics in a solution in a beaker, with no costly vacuum chambers or clumsy kilns.

This new ceramic, which they call a "defect chemistry superlattice," is made from sandwichlike layers of thallium (III) oxide. Using electrochemical deposition, the scientists build the layers one at a time by pulsing electric current through the solution.

The ceramic's main advantage, says Robert Van Leeuwen, a chemist and coauthor, is its quick, cheap, and easy production. "Instead of using a $2 million molecular beam epitaxy machine, which most people use to make copper oxide superconductors, a high school student could make this material with a few thousand dollars' worth of equipment."

Of interest, too, are the new compound's optical properties. Like optical fibers, the new material transmits light efficiently in the near infrared, "where most optical communication occurs these days," Van Leeuwen explains. The ceramic may also find a use in optical switches in high-speed computers.

Owing to its structure and chemical properties, the new ceramic can conduct electricity almost as well as metal can, Switzer says. The compound may also prove to be a superconductor. Currently, the chemists are trying to determine if it can superconduct and, if so, at what temperature.