(FEI - 1994)
TEXTO PARA A PRÓXIMA QUESTÃO:
MERCURIAL SUPERCONDUCTOR SHOWS AN ACCEPTABLE FACE
By Maria Burke
IN New Scientist 21 August 1993, pp.16
IN March, a new high-temperature superconductor based on mercury was made by a Russian scientist. Now a team of American scientists has discovered that is possesses a property unique among such materials: it is easy to fabricate, making it very attractive commercially.
Most high-temperature superconductors, which are based on yttrium or bismuth, have properties WHICH depend on how the particles are aligned. So in order to produce the best results, all the particles must be made to point in the same direction, a process which is time-consuming and expensive.
For example, bismuth-based superconductors are usually made in a complex rolling, drawing and heating process, which limits the shapes that can be made. But Jennifer Lewis and her colleagues at the University of Illinois and the Argone National Laboratory found that the magnetic properties of the mercury superconductor do not depend on the way in which its particles are aligned. This was true at magnetic fields of about 1 tesla - similar to normal operating conditions - but not at very low fields. The researchers embedded particles of' the material, which also contains atoms of barium, copper and oxygen, in an epoxy matrix.
Easier fabrication would be a substantial money-saver for industry. However, the synthesis of the new superconductor is a little dangerous because it involves mercury, a hazardous substance.
Lewis and her colleagues have prepared a paper soon to appear in the journal Physical Review B.
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