Scientists say they have discovered superconductivity — the ability to conduct electricity perfectly — at the highest temperatures ever recorded.
The researchers at the University of Chicago in the USstudied a class of materials in which they observed superconductivity attemperatures of about minus 23 degrees Celsius — a jump of about 50 degreescompared to the previous confirmed record.
Though the superconductivity happened under extremely highpressure, the result still represents a big step towards creatingsuperconductivity at room temperature — the ultimate goal for scientists to beable to use this phenomenon for advanced technologies.
Just as a copper wire conducts electricity better than arubber tube, certain kinds of materials are better at becoming superconductive,a state defined by two main properties.
The material offers zero resistance to electrical currentand cannot be penetrated by magnetic fields, according to the results published in the journal Nature.
The potential uses for this are as vast as they areexciting: electrical wires without diminishing currents, extremely fast supercomputersand efficient magnetic levitation trains, said Vitali Prakapenka, a researchprofessor at the University of Chicago.
However, scientists have previously only been able to createsuperconducting materials when they are cooled to extremely cold temperatures— initially, minus 240 degrees Celsius and more recently about minus 73degrees Celsius.
Since such cooling is expensive, it has limited theirapplications in the world at large.
Recent theoretical predictions have shown that a new classof materials of superconducting hydrides could pave the way forhigher-temperature superconductivity.
Researchers at the Max Planck Institute for Chemistry inGermany teamed up with University of Chicago to create one of these materials,called lanthanum superhydrides, test its superconductivity, and determine itsstructure and composition.
The only catch was that the material needed to be placedunder extremely high pressure — between 150 and 170 gigapascals, more than oneand a half million times the pressure at sea level.
Only under these high-pressure conditions did the material— a tiny sample only a few microns across — exhibit superconductivity at thenew record temperature.
The material showed three of the four characteristics neededto prove superconductivity.
It dropped its electrical resistance, decreased its criticaltemperature under an external magnetic field and showed a temperature changewhen some elements were replaced with different isotopes.
The fourth characteristic, called the Meissner effect, inwhich the material expels any magnetic field, was not detected.
That is because the material is so small that this effectcould not be observed, researchers said.
In the experiment, researchers squeezed a tiny sample of thematerial between two tiny diamonds to exert the pressure needed, then usedX-rays to probe its structure and composition.Since the temperatures used to conduct theexperiment is within the normal range of many places in the world, that makesthe ultimate goal of room temperature — or at least zero degrees Celsius —seem within reach, researchers said.