photo/©: Thomas Hartmann
Researchers of the Max Planck Institute for Chemistry and
Johannes Gutenberg University Mainz observed new record high for
superconductivity / Publication in Nature
(August 19, 2015) Researchers
at the Max Planck Institute for Chemistry in Mainz and Johannes Gutenberg
University Mainz observed that hydrogen sulfide becomes superconductive at
minus 70 degree Celsius – when the substance is placed under a pressure of 1.5
million bar. This corresponds to half of the pressure of the earth's core. With
their high-pressure experiments the researchers in Mainz have thus not only set
a new record for superconductivity, their findings have also highlighted a
potential new way to transport current at room temperature with no loss. Their
scientific paper "Conventional superconductivity at 203 K at high
pressures" was published in the renowned journal Nature on August 17,
2015.
For many solid-state physicists, superconductors that are
suitable for use at room temperature are still a dream. Up to now, the only
materials known to conduct current with no electrical resistance and thus no
loss did so only at very low temperatures. Accordingly, special copper oxide
ceramics, so-called cuprates, took the leading positions in terms of transition
temperature, i.e., the temperature at which the material loses its resistance.
The record for a ceramic of this type is roughly minus 140 degrees Celsius at
normal air pressure and minus 109 degrees Celsius at high pressure. In the
ceramics, a special, unconventional form of superconductivity occurs. For
conventional superconductivity, temperatures of at least minus 234 degrees
Celsius have so far been necessary.
A team led by Dr. Mikhael Eremets, head of the working group
"High pressure chemistry and physics" at the Max Planck Institute for
Chemistry, working in collaboration with Dr. Vadim Ksenofontov und Sergii
Shylin of the Institute of Inorganic Chemistry and Analytical Chemistry at
Johannes Gutenberg University Mainz has now observed conventional superconductivity
at minus 70 degrees Celsius in hydrogen sulfide (H2S). To convert the
substance, which is a gas under normal conditions, into a superconducting metal
the scientists did however have to subject it to a pressure of 1.5 megabar or
1.5 million bar.