In 2015, Mikhail Eremets, a physicist at the Max Planck Institute for Chemistry in Mainz, reported that hydrogen sulfide – a molecule made up of two hydrogen atoms and one sulfur atom – became superconducting at a pressure of about 22 million pounds per square inch at minus 94 degrees Fahrenheit. That was a record temperature for a superconductor back then.
“This is what I would say is the groundbreaking paper that sets the tone,” said Dr. Slides.
Dr. Eremets and other scientists then discovered that lanthanum hydride – a compound containing hydrogen and lanthanum – reached a superconducting temperature of minus 10 degrees Fahrenheit at ultra-high pressures.
Dr. Dias’ group studied a mixture of three elements: hydrogen, sulfur and carbon. With three elements, the scientists were able to adjust the electronic properties in order to achieve the higher superconducting temperatures.
“You can start with knowing what the good binary systems are and then potentially add another element to get more complex,” said Eva Zurek, professor of chemistry at the University of Buffalo who does numerical calculations on behavior predict the high -print materials. “And hopefully this complexity can raise the superconducting critical temperature or lower the stabilization pressure.”
Dr. Zurek, who was not involved in the latest research, said carbon was a good third element because it formed strong bonds that could potentially hold the material together. “If you take the pressure off, those ties may not break,” she said.
To make the superconductor, the scientists had to squeeze the substance between two diamonds to nearly 40 million pounds per square inch. That is roughly the pressure you would experience if you could tunnel more than 3,000 miles into the earth and land at the bottom of the outer core of molten iron.
The process created patches of material over the volume of a single inkjet particle.
The experimental results did not completely agree with Dr. Zurek’s computer calculations match that predicted the highest superconducting temperatures at lower pressures. Dr. Instead, Dias found that the superconducting temperature continued to rise with increasing pressure.