Department of Physics

By the way, here are a few other pages for people with advanced WWW browsers:

• If you use Netscape 3.0, or have a VRML viewer, see a Fullerene molecule in 3D: VRML of C₆₀
• Take a virtual tour inside the various doped C₆₀ structures!
• MPEG movie of C₆₀ (681Kb Big!) made by Michael C. Martin, using the Moviemol molecular animation program.
• See also the Stony Brook Buckyball Server.

	In order to make solids, first we need the material in large quantities. This is why we consider the 1990 contribution of W. Krätschmer and D.R. Huffman so important. They gave us an inexpensive and efficient method to produce (kilo)grams of this stuff! Instead of looking at the interstellar space, or studying some mass spectra, we can grab the material and look at it with "table top" experiments. Of all the fullerenes C60 is produced in the largest quantities. Nowadays one can buy purified C60 at reasonable prices. For interested parties, here is a WEB page describing the "Krätschmer - Huffman" method of preparation.
	The solid C60 crystallizes in the fcc structure. In this respect, the fullerene molecules behave more or less like perfect spheres. (In fact, at room temperature the bucky balls are not at rest: they rotate continuously and randomly.) The fcc structure is well known from metallurgy: this is the most densely packed structure. (Here is an MPG movie of the fcc structure from the LASSP, Cornell University.) However, there is a major structural difference between ordinary metals and the solid fullerene: with the C60 as a building block, there is plenty of empty space between the balls, even if the packing is as close as possible. This opens up the possibility of putting other atoms into the structure.
	Solid C60 differs from simple metals in another crucial property: it is an insulator. But we have space for other atoms; let us see what can we do! Here, for example, one Rb atom is placed into the larger (called octahedral) holes between the buckyballs. This material is a metal. Simply speaking, an electron is donated from the Rb atom to the buckyball, and this electron can easily move around by jumping from one ball to the next. Quite a few of our published papers deal with this compound.
	Even more interesting is the K3C60. As discovered in 1991 by a research group in the Bell Laboratories this compound becomes a superconductor if cooled to low temperatures. In the picture on the right the buckyballs are represented by yellow spheres, and the potassium ions are light and dark blue. The structure of this and related materials has been determined in a collaboration between UCLA and Stony Brook researchers. Our most recent work discusses a particularly important property of this supercondutor.
	Yet another material is an organic ferromagnet. This one was made by Fred Wudl at UC Santa Barbara.

When we started to look at buckyballs put together in a solid, we found a whole new world, waiting to be discovered. The fullerene molecule proved to be the basic building block of larger structures with surprising properties. At this point we can not say for sure if any one of these compounds will be as useful as semiconductors are, or nuclear magnetic resonance is. As the XIXth century physicist Michael Faraday said, when asked about the usefulness of electricity: "But who knows what is a newborn baby good for?"

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