THE FUTURE OF LOW-TEMPERATURE SUPERCONDUCTORS Superconductivity is still a relatively new area of science,
and
although much research is now focused on high-temperature
cuprate perovskite superconductors, there remain significant research efforts
dedicated to developing
radically
different types of superconductive material. Some of the potentially
most useful
low-temperature superconductive products of recent research have been
based around
doped carbon. In particular, the superconductivity of doped
buckmisterfullerene (a spherical arrangement of 60 carbon
atoms) was correctly predicted in 1964, 16
years before the first buckminsterfullerene-based superconductor was
synthesised.
It has more recently been discovered that carbon nanotubes (carbon
atoms arranged in a tubular structure) superconduct without requiring
doping. These tubes have a wall one
or more atoms
thick, and given their tubular nature might be suitable for the
construction of superconducting integrated circuits.
Unfortunately, they are difficult to fabricate for this application,
and require extreme refrigeration before the
superconductivity is evidenced. Nevertheless, there have been recent
breakthroughs in the creation of nanotube transistors, which lay the
groundwork for more complicated electronics based solely on novel
superconductive components. Heating nanotubes in the presence of lead
has been shown to draw the metal into the tubes as if by
capillary action, and given lead's known superconductivity, this may
provide an alternative route to superconducting electronics.
Another breakthrough that has been made very recently is the
manufacture of metallic hydrogen. While this was predicted in
the 1930s, and more recently theorized to be superconductive at temperatures possibly reaching 290K, the
extreme conditions required to fabricate it have been outside the reasonable reach
of technology until recently. However, the discovery of magnesium
diboride superconductivity at 40K
provides an experimental
model of low-temperature superconductivity in boron which may be
applicable to other materials such as metallic hydrogen.
The discovery
of BCS superconductivity at high temperatures may lead to a significant
shift in the definitions of low- and high-temperature superconductivity
used today.
