Scientists from the Texas Center for Superconductivity (TcSUH) and the University of Houston department of physics reached a superconducting transition temperature (Tc) of 151 Kelvin (about minus 122 degrees Celsius). That is now the highest Tc ever reported for a superconductor functioning at ambient pressure since superconductivity was first discovered in 1911.

The transition temperature marks the point where a material can carry electricity with zero resistance. Increasing this temperature has been one of the biggest goals in superconductivity research because higher operating temperatures could make superconducting technologies far more practical and affordable.

The findings by physicists Ching-Wu Chu and Liangzi Deng were published in the Proceedings of the National Academy of Sciences. Funding for the work came from Intellectual Ventures, the state of Texas through TcSUH, and several foundations.

"Transmitting electricity in the grid loses about 8% of the electricity," said Chu, professor of physics, TcSUH founding director and the paper's senior author. "If we conserve that energy, that's billions of dollars of savings and it also saves us lots of effort and reduces environmental impacts."

Why Superconductors Matter

Superconductors are materials that allow electricity to flow without resistance. Because no energy is lost as heat, they could dramatically improve the efficiency of electrical systems. Scientists also see superconductors as critical for technologies such as magnetic resonance imaging (MRI), fusion reactors, quantum technologies, and ultrafast electronics.

The challenge is that most superconductors only work at extremely low temperatures, requiring expensive cooling systems that limit widespread use.

"Once we bring the material to ambient pressure, it becomes much more accessible for scientists to use well-developed instrumentation to investigate it and further develop technologies for ambient condition operations," said Deng, assistant professor of physics, principal investigator at the TcSUH and lead author of the paper.

New Record Breaks Decades-Old Barrier

Researchers have spent decades searching for superconducting materials with increasingly higher transition temperatures.

A major milestone came in 1987 when Chu and his collaborators discovered that a material known as YBCO could become superconducting at minus 180 degrees C, or 93 K. That discovery helped launch a global race to develop high-temperature superconductors.

In 1993, scientists discovered a mercury-based copper-oxide ceramic called Hg1223 that reached superconductivity at minus 140 degrees C, or 133 K. That material held the ambient-pressure record for more than 30 years.

The new University of Houston achievement pushes the record 18 degrees C higher to 151 K.

Pressure Quenching Creates Stable Superconductivity

The breakthrough relied on a process known as pressure quenching. While pressure techniques are commonly used in other fields, including diamond production, the method is relatively new in superconductivity research.

Researchers first subjected the material to extremely high pressure, which enhanced its superconducting behavior and increased its transition temperature. While still under pressure, the material was cooled to a carefully chosen temperature before the pressure was suddenly removed.

That rapid release effectively preserved the enhanced superconducting properties, allowing the material to remain stable even after returning to normal pressure conditions.

"Other researchers have shown that reaching superconductivity at room temperature under pressure is achievable," Chu said. "Our method shows that it is possible to retain that state without maintaining pressure."

A Step Toward Room-Temperature Superconductors

Although room-temperature superconductivity at ambient pressure remains out of reach, researchers say the new record is an important advance toward that goal. Room temperature is roughly 300 K, leaving a gap of about 140 degrees C from the newly achieved record.

"This finding has great potential," Chu said. "We believe, with enough people working on it and given enough time, we should be able to realize the potential."

Chu and Deng also contributed to a companion perspective paper funded by Intellectual Ventures and published in PNAS. The paper discusses six different approaches researchers could use to raise superconducting temperatures further, including pressure quenching.

"Room-temperature superconductivity has been seen as a 'holy grail' by scientists for over a century," said Rohit Prasankumar, director of superconductivity research at Intellectual Ventures. "The UH team's result shows that this goal is closer than ever before. However, the distance between the new record set in this study and room temperature is still about 140 degrees C. Closing this gap will require concerted, intentional efforts by the broader scientific community, including materials scientists, chemists, and engineers, as well as physicists."