THREE-DIMENSIONAL POLYMER WITH UNUSUAL MAGNETISM
Date: Monday, November 13, 2006 @ 20:44:27 UTC Topic: Science
Up to now it has not been possible to fabricate magnets from organic materials,
like for example plastics. Recently, however, experiments at the
Forschungszentrum Dresden-Rossendorf (Germany) in collaboration with an
international research team have revealed magnetic order in a polymer. The
structure which consists in particular of hydrogen, fluorine, carbon and copper,
has been realized in an entirely novel, three-dimensional and very stable form.
This will be described in an upcoming issue of the journal Chemical
Communications.
Magnetism is a physical property of matter related to the magnetic
spins of electrons. Iron, for example, is a ferromagnet because these
spins are aligned parallel to each other, generating a uniform magnetic
field. Antiferromagnetism, on the other hand, arises when neighboring
spins are oriented antiparallel to each other.
Such antiferromagnetism has been shown to exist for the new
polymeric compound studied at the Forschungszentrum Dresden-Rossendorf
(FZD). This polymer is characterized by a novel and unusual structure
where copper atoms together with pyrazin-molecules build layers, which
in turn through bridges of hydrogen and fluorine are connected with
each other. The three-dimensional polymer was prepared by chemists
working with Jamie Manson at Eastern Washington University and was
subsequently studied by physics teams in Great Britain and in the
research center in Dresden-Rossendorf.
Metallic copper is not magnetic. Joachim Wosnitza and his
colleagues at the Dresden High Magnetic Field Laboratory discovered at
a temperature of 1.54 Kelvin – that is 1.54 degrees above absolute zero
at -273.15 °C – that the embedded copper atoms order themselves
antiferromagnetically. In the compound, every copper ion possesses a
magnetic spin which interacts with neighboring spins through organic
units. How this interaction arises and how it can be influenced is
presently under investigation.
Additional polymeric samples from the laboratory of Manson will be
studied at the Forschungszentrum Dresden-Rossendorf with the objective
of a better understanding of the newly discovered magnetism for this
class of polymers. In the future, this would be a significant step, to
synthesize organic materials with tailored magnetic properties.
Permanent magnets can be made from iron and other ferromagnetic
materials, from polymers this is, according to the current knowledge,
not possible. The great vision of the scientists is to realize
ferromagnetic properties for novel polymeric compounds that eventually
would permit the development of innovative magnets.
Source: Forschungszentrum Rossendorf
Article from: http://www.physorg.com/news82641225.html
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