Troubling connections.Troubling connections Making an electrical connection An electrical connection between discrete points allows the flow of electrons, (current). A pair of connections is needed for a circuit. Between points with a low voltage difference between them, direct current flow can be controlled by a switch. between a high-temperature superconductor A material that has little resistance to the flow of electricity. Traditional superconductors operate at absolute zero (-459.67 degrees Fahrenheit or -273.15 degrees Celsius). Experiments in the 1980s raised the temperature to -321 degrees Fahrenheit. and a metal wire may be trickier than many researchers had hoped or expected. A series of careful studies conducted by John H. Weaver of the University of Minnesota (body, education) University of Minnesota - The home of Gopher. http://umn.edu/. Address: Minneapolis, Minnesota, USA. in Minneapolis and his collaborators reveals that metals such as titanium, iron copper and aluminum react with a ceramic superconductor. The reaction often disrupts the superconductor's surface to create a layer that is no longer superconducting. "These are fragile surfaces," Weaver says. The only metals that appear to be safe for making electrical contact with a copper-oxide-based superconductor are gold and silver. The researchers have also found that depositing layers of compounds such as aluminum oxide aluminum oxide: see alumina. or calcium fluoride can protect a superconducting surface without disrupting and changing the surface's properties. |
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