University of Saskatchewan Canada Research Chair John Tse and colleagues in Germany have identified a new family of superconductors – research that could eventually lead to the design of better superconducting materials for a wide variety of industrial uses.
In an article published in the journal Science, the team has produced the first experimental proof that superconductivity can occur in hydrogen compounds known as molecular hydrides.
“We can show that if you put hydrogen in a molecular compound and apply high pressure, you can get superconductivity,” said Tse. “Validation of this hypothesis and understanding of the mechanism are initial steps for design of better super-conducting materials.”
Superconductors conduct electricity without creating friction or heat loss. An electric current can therefore flow in a loop of superconducting wire indefinitely with no power source. Examples of existing superconducting materials include magnets used in MRI machines and the magnets that enable high-speed trains to float above the track without friction or energy loss as heat.
Team member Mikhail Eremets of the Max Plank Institute in Germany did the laboratory work in detecting superconductivity in the hydrogen compound silane, while Tse and his graduate student Yansun Yao provided the theoretical basis for understanding the mechanism involved and identified the key chemical structures.
Most commercial superconducting materials have to operate at very low temperatures which requires expensive super-cooling equipment.
“Our research in this area is aimed at improving the critical temperature for superconductivity so that new superconductors can be operated at higher temperatures, perhaps without a refrigerant,” said Tse.
It has long been hypothesized that hydrogen, the simplest of the elements, may be able to conduct electricity without creating friction or heat loss (superconductive behavior) if it’s compressed into a very dense solid form. Though many researchers have tried using pure hydrogen, they have not been able to achieve the necessary hydrogen density to produce superconductivity.
Instead of using pure hydrogen, the Germany-Canada team, following an earlier suggestion by Prof. Neil Ashcroft at Cornell University, compressed hydrogen-rich molecules (hydrides). They were able to reach the necessary density for superconductivity at much lower pressure than with pure hydrogen – an achievement that will shed greater understanding on the fundamental nature of superconductivity.
The U of S work, funded by NSERC and the Canada Research Chairs program, involved extensive calculations – some taking as long as a month – at the WestGrid computing facility and with the Canada Foundation for Innovation-funded high-performance computing facility at the U of S.
In related research, Tse’s team is using the Canadian Light Source synchrotron to study high pressure structures of other hydrides systems on potential superconductivity and making use of them to store hydrogen for fuel cells.
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