June 25, 2003 12:51 PM PDT
IBM meta-molecules open new doors
Collaborating with researchers from Columbia University and the University of New Orleans, IBM was able to create an environment where lead selenide, a semiconductor with optical properties, and iron oxide, a magnetic material, combined to form large crystals exhibiting electrical, optical and magnetic properties.
A paper on the experiment will be published this week in the journal Nature.
Years from now, materials like this could, hypothetically, be used to make optical equipment with light that's controlled by magnetic fields, said Christopher Murray, manager of nanoscale materials and devices at IBM Research.
The method for combining these materials, however, is just as important as the result in this experiment. These so-called meta-materials, which consist of tens of thousands of atoms, don't occur naturally. The basic crystal unit in this experiment, for instance, consists of 63,000 atoms. They also exhibit behavior not found in the separate materials.
"This is something where two plus two equals five," Murray said. "Our building blocks are much larger than those in classical chemistry."
Meta-materials hold the potential for substantially changing the field of chemistry because they allow researchers to find new materials exhibiting as-yet-unknown characteristics out of more basic molecules that have been studied for years and, to a large degree, are fairly well understood. The potential for finding new, untapped properties is largely the promise of nanotechnology.
"Some people refer to this area as developing a new periodic table," Murray said. "We see phenomena that is not represented in the current materials but is represented in the collective materials."
Another key breakthrough in the experiment was getting the molecules to assemble themselves. In the early 1990s, IBM managed to arrange a series of atoms with a scan probe microscope to spell "IBM."
This experiment differs in that the molecules moved themselves and formed three-dimensional, rather than two-dimensional, structures. Kyung Sang Cho, a researcher at the Advanced Materials Research Institute of the University of New Orleans, designed the lead selenide particle, while Franz Redl from Columbia designed the iron oxide particles. Redl then tailored the experimental conditions under which the particles assembled themselves into repeating crystals.
"What we'd like to do is extend that assembly process to larger levels of organization.
In many ways, research in this area is just beginning. Researchers are now trying to come up with materials that can combine into different meta-materials. Taking meta-materials and turning those into products will likely take years.