Oxygen gets superconducting powers.Oxygen, essential for life and one of the most abundant elements on Earth, has now acquired another distinction. It is the first gas to be made superconductive, a team of researchers in Japan reports. "This experiment is a big advance [toward] hydrogen, which is theoretically expected to be a 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. in the metallic state," says Katsuya Shimizu of Osaka University. Shimizu and his colleagues chilled oxygen almost to absolute zero and squeezed it in a diamond anvil cell A diamond anvil cell (DAC) is a device used by physicists to exert extreme pressures on a material. It consists of two opposing cone-shaped diamonds squeezed together. The resultant high pressures — in excess of a million atmospheres — are produced when force is applied (SN: 10/26/96, p. 261). At nearly 1 million times atmospheric pressure, the gas becomes a metal and loses its electrical resistance, they report in the June 25 Nature. To demonstrate superconductivity superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Kamerlingh Onnes, who found that the resistance of mercury dropped suddenly to zero at a temperature of about 4.2°K;. , the researchers connected metal electrodes to the tiny, solid oxygen sample. They had to design a layer of aluminum oxide aluminum oxide: see alumina. to insulate the oxygen and electrodes from the metal chamber that held the sample, says Shimizu. |
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