Repurposing deep-Earth tools in the hunt for practical superconductors
This story originally appeared in Yale Engineering magazine.
If scientists could find a material that acts as a superconductor — that is, one that transmits energy with zero resistance — at normal pressures and relatively high temperatures, it would open up a massive number of possibilities. These include medical imaging, quantum computing, and numerous other fields. So, yes, it would be a big deal.
“Right now, almost 50% of the energy in transmission is just heat in copper wires,” said Shomeek Mukhopadhyay. “If you can transmit electricity through wires without dissipating energy, that’s a huge economic benefit. I would say it’s equivalent to having thermonuclear fusion.”
Mukhopadhyay, a research scientist in Chemical & Environmental Engineering, is on the third floor of the Kline Geology Laboratory. Nearby, Natalia Nevskaya, a postdoctoral associate in Earth & Planetary Sciences preps a massive device called the Kawai multi-anvil press. The machine is designed to simulate Earth’s deep mantle conditions by generating very high temperatures and extreme pressures. Its intended purpose is for studying materials billions of years old, but for the past five years or so, a multidisciplinary group of scientists has been using it to potentially create materials of the future. Heading up the project is Lisa Pfefferle, the C. Baldwin Sawyer Professor of Chemical & Environmental Engineering.
Natalia Nevskaya positions a sample cube into the Kawai multi-anvil press, preparing to simulate extreme deep-Earth pressures for superconductivity experiments.
Specifically, they’re aiming to create materials that act as superconductors under normal pressure levels and at relatively high temperatures (when discussing superconductivity, “relatively high temperatures” usually means anything above the temperature liquid nitrogen freezes, or about -196 Celsius). Currently, they’re focusing on sulfur trihydride (H3S). A close relative of hydrogen sulfide (H2S), H3S is made up of three parts hydrogen to one part sulfur. It began getting attention a few years ago when scientists found that it acted as a superconductor at higher-than-normal temperatures (about -23 Celsius). The catch is that it did so only under extreme pressures — 150 to 200 gigapascals (the unit of measurement is named for Blaise Pascal, who helped clarify our concept of pressure). That’s the kind of pressure found halfway to Earth’s core, approximately 3,200 kilometers into the Earth’s interior. Such pressure levels are obviously too high for any practical use, and the superconductivity disappears once the pressure is released.
So the trick then is, how do you get it to stay superconductive after relieving the pressure? And at a temperature high enough to make it practical?
Researchers in Pfefferle’s lab think they may have found a way and have teamed up with researchers from Yale’s Earth & Planetary Sciences and Chemistry departments, as well as the U.S. Navy, to help them achieve it.
One of the inconvenient things about H3S is that it’s highly unstable. Under normal conditions, it essentially dissipates. To that end, Pfefferle’s lab has made a significant breakthrough, developing a technique to synthesize H3S under much lower pressures (about 15 gigapascals), and in a way that it remains stable after the pressure is relieved. As for making it superconductive, they’ve already seen some encouraging results while working with other materials. Last year, they were able to turn platinum into superconductors. Doing so required super-low temperatures (about 2 degrees above absolute zero or 6 Kelvin), “but the interesting thing is that this material, which is never superconducting, can turn superconducting,” Mukhopadhyay said. That is, they were able to “freeze” those materials’ superconductive properties after letting up on the pressure. So the next step is to see if they can freeze the superconductivity of H3S at both higher temperatures and ambient pressures.
The method they’ve developed for doing so involves placing sulfur and a hydrogen precursor between two graphene sheets with only a few nanometers of spacing. Metal particles are also placed between the graphene sheets to generate strain and induce more pressure. Platinum is the preferred choice of metal particle, as it also works best as a catalyst for the hydride formation. The choice of graphene as a material is important because it’s flexible and does not break under extreme pressure.
“What we have shown is that with this graphene sheet system, we can produce H3S at lower pressures because constraint — having two walls very close together of the order of half a nanometer — acts like high pressure,” Mukhopadhyay said. “So instead of producing it at pressures found at the Earth’s crust, we can produce it with 10 times less pressure.”
Heike Kamerlingh Onnes, a Dutch physicist, discovered superconductivity in 1911 when he observed that mercury had zero resistance to electricity when it was cooled to a few degrees above absolute zero. Ever since, scientists have struggled to understand the phenomenon, and importantly, find a way to put it to practical use. As researchers searched for ways to harness it for various applications — everything from levitating trains to portable MRIs to quantum computing — the idea of superconductivity proved as confounding as it was promising. The few times it has been discovered at relatively high temperatures, it has required extremely high pressures.
Pfefferle’s interest in this line of research has its roots in her extensive work with nanotubes. Boron nanotubes, it turns out, have superconductive properties. That led Pfefferle to look further into the matter of superconductivity.
“For the past several years, people have been recording higher temperature superconductivity for a number of compounds, especially hydrides, but only when they’re at very, very high pressures,” she said. “So our work with the geology team was in order to use their different pressurization devices.”
“If you can transmit electricity through wires without dissipating energy, that’s a huge economic benefit. I would say it’s equivalent to having thermonuclear fusion.
Shomeek Mukhopadhyay
research scientist, Chemical & Environmental Engineering
Her lab reached out to Nevskaya and Jennifer Girard, a research scientist in Earth & Planetary Sciences. Victor Batista, the John Gamble Kirkwood Professor of Chemistry, has also lent his expertise to the project. Curious though she was about this line of research, Pfefferle wondered what practical benefits there could be if all these materials just lost their superconductive powers once they returned to ambient conditions.
“So I thought, ‘OK, strain and confinement are likely possibilities,’” she said. That is, what if they could find a way to apply pressure in such a way that the acquired properties became stable at ambient pressure? “So I put together a model system of H2S between two graphene layers to test our ideas.”
Batista’s group modeled this system, showing that the confinement effect could allow formation of the superconducting H3S phase at much lower pressures; this motivated the Pfefferle lab’s experiments.
For the next phase of their work — inducing superconductivity in H3S — they’ve received a 5-year grant from the Naval Research Laboratory. Some of that work will take place at Argonne National Laboratory in Illinois. There, they’ll make use of high-pressure machines that allow users to see the actual process as it happens. And as part of their collaboration, they’ll use the U.S. Navy’s Superconducting Quantum Interference Device (SQUID) magnetometer to measure the magnetic fields of the samples. The SQUID is critical to their research because it can pick up on the small samples’ very low magnetic fields (about a billion times weaker than those of the Earth). That’s crucial, because when a material takes on superconductivity, it expels its magnetic field. Ultimately, they want to hone their methods so that they’re reliably reproducible, and viable for industry and military use.
Pfefferle’s lab has been working with the Earth & Planetary Sciences department for about five years. In the Kline Geology Lab, they’ve made good use of the Kawai multi-anvil press, which applies extreme pressure to its sample from all directions. When discussing extreme pressure levels, the researchers tend to identify each level according to its proximity to the Earth’s core.
“There’s not much on the Earth’s surface that reaches these high pressures,” Nevskaya explains. “That’s why they built this machine. The history of the machine is not superconductivity, it’s geology. The idea of the machine is to reach lower mantle conditions, or even beyond. We know a lot about the oceans. We know a lot about space — in fact, we know more about space than about what is actually happening beneath our feet.”
As more has been learned about superconductivity and the effects of extreme pressures, Mukhopadhyay notes, materials scientists and geologists have increasingly been teaming up to see what more they can learn.
“The landscape has changed significantly because I think people realize there’s a lot of overlap between mineral physics or high pressure, rock studies, and material science,” he said.
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Published Date
Aug 4, 2026
