FIGURE 9.6 Computer graphic showing how potassium atoms (smaller balls) fit in between larger buckyballs to make an artificial metal that becomes superconducting when chilled to 18 degrees Kelvin. (Courtesy of University of California, Los Angeles/State University of New York.)

much potassium should be allowed to slip into the carbon network to make it superconducting, and they speculated that a three-to-one ratio of potassium to buckyballs was required. Whetten and his co-workers at UCLA began painstaking experiments to quantify the superconducting formula for this particular artificial metal and confirmed the Bell Labs group's suspicions that a three-to-one ratio is correct. Through this work the UCLA team also found a method to produce this artificial metal so that a large fraction of it ends up with the correct potassium-to-C60 ratio for superconductivity. The original material prepared by the Bell Labs team was only about 1 percent superconducting. Within months—attesting to the pace of fullerene advances—the UCLA team improved the material first to 60 percent superconducting and then all the way to 100 percent.

In the meantime, the Bell Labs and UCLA researchers were also trying to slip other atoms into the buckyball crystals to see the effect on

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