&Bullet; physics 14, p36
A new synthesis technology brings high-temperature superconducting materials one step closer to ambient pressure.
In October 2020, Elliot Snider from the University of Rochester, New York, and colleagues demonstrated superconductivity at room temperature at high pressures. With a new synthesis method, the group has now created a material that is superconducting at a similar temperature but lower pressure  . The new technology could lead to the development of further novel superconducting materials and thus to new possibilities to test theories of superconductivity.
As in the previous year, the researchers used a diamond anvil cell in their new demonstration to create a hydrogen-rich compound under high pressure. In the previous experiment, the researchers combined hydrogen with carbon and sulfur. This time they combined the hydrogen with yttrium, a reactive transition metal, to create superconducting yttrium superhydride. Specifically, the researchers placed gaseous hydrogen and solid yttrium between two diamond anvils, with the two materials being separated by a thin layer of palladium. The palladium layer shielded the yttrium and prevented oxidation, but also acted as a catalyst and helped transport hydrogen atoms into the yttrium.
It is believed that high hydrogen content promotes high temperature superconductivity and the new formulation confirms this. The new material is superconducting at around 262 K and 182 GPa – a significantly lower pressure than the roughly 267 GPa required for last year’s room temperature superconductor, but still far too high for practical applications.
The researchers hope that the technique will enable the synthesis of other high-temperature superconductors and thus lead to a better understanding of the structures and mechanisms behind the phenomenon. The ultimate goal is to find high-temperature superconductors that work at lower pressures and to develop ways to synthesize them in large quantities.
–Erika K. Carlson
Erika K. Carlson is Corresponding Editor for physics based in New York City.
- E. Snider et al., “Synthesis of yttrium superhydride superconductors with a transition temperature of up to 262 K by catalytic hydrogenation at high pressures”, Phys. Rev. Lett.126, 117003 (2021).