Tuesday, March 17, 2009
Superconductors transport electrons with zero resistance by synchronizing their movement through changes in the internal structure of materials. Hence, no physical collisions occur. The exact character of these changes has been the subject of much speculation, prompting over 100,000 scholarly papers on the subject in the last 20 years. A novel theory developed by university reseachers in the U.S. and China now attempts to explain high-temperature superconductivity using a new class of materials discovered last year called iron pnictides (pronounced NIK-tides). The key to high-temperature superconductors, according to the new theory, is their different "quantum phases," which are similar to the difference between solids and liquids, according to researchers from Rice University, Rutgers University, Zhejiang University and the Los Alamos National Laboratory. Ice and water are two phases of H2O; above the critical melting point the molecules are ordered as solids, but below it they melt in a disordered liquid. Likewise, above its critical melting point, the quantum phase of high-temperature superconductors is antiferromagnetic; below it, they melt into magnetic disorder.
BOTTOM LINE: Superconductors can supply unlimited energy by virtue of their perpetual motion around coils whose resulting magnetic energy is used today for tasks that would otherwise be too expensive to power--such as levitating trains. Unfortunately, such superconductors have to be cooled to near absolute zero, the cost of which confines their applications to really big projects. High-temperature superconductors, on the other hand, reduce the cooling costs, but they are not well understood. These researchers claim to have an explanation for high-temperature superconductors that could lead to the fabrication of designer materials that supply perpetual-motion-like energy generation. The theory will be proven out experimentally within a year, and if its valid, could eventually lead to room-temperature superconductors within our decade.
Posted by R. Colin Johnson at 9:16 AM