Researchers at the University of Houston have achieved a major advance in superconductivity by setting a new temperature record for superconductors operating under atmospheric pressure conditions. This progress could ultimately help create more efficient power grids, improved energy storage systems, faster electronics, and new technologies for fusion energy and medical imaging.
Scientists from the Texas Superconductivity Center (TcSUH) and the University of Houston Department of Physics have reached a superconducting transition temperature (Tc) of 151 Kelvin (about minus 122 degrees Celsius). This is the highest Tc ever reported for a superconductor functioning at atmospheric pressure since superconductivity was first discovered in 1911.
Transition temperature indicates the temperature at which a material can conduct electricity with zero resistance. Increasing operating temperatures has the potential to make superconducting technology more practical and affordable, making it one of the biggest goals in superconductivity research.
The research results by physicists Chin Wu Chu and Liangji Deng are Proceedings of the National Academy of Sciences. Funding for this research was provided by Intellectual Ventures, the State of Texas through TcSUH, and several foundations.
“When we transmit electricity through the grid, about 8% of the electricity is lost,” said Chu, a physics professor, founding director of TcSUH and lead author of the paper. “If we can save energy, we can save billions of dollars, we can save a lot of labor, and we can reduce our environmental impact.”
Why superconductors are important
A superconductor is a material that allows electricity to flow without resistance. Because no energy is lost as heat, the efficiency of electrical systems can be dramatically improved. Scientists also believe superconductors are important for technologies such as magnetic resonance imaging (MRI), fusion reactors, quantum technology, and ultrafast electronics.
The challenge is that most superconductors only operate at extremely low temperatures, requiring expensive cooling systems, limiting their widespread use.
“Bringing materials to atmospheric pressure makes it much easier for scientists to use well-developed instruments to investigate materials and further develop techniques for manipulating them in atmospheric conditions,” said Deng, assistant professor of physics, principal investigator at TcSUH, and first 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 Celsius, or 93 K. This discovery helped launch a worldwide 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 Celsius, or 133 K. This material held atmospheric pressure records for over 30 years.
New results from the University of Houston push the record 18 degrees higher to 151K.
Achieving stable superconductivity through pressurized quenching
This breakthrough technology relied on a process known as pressure quenching. Although pressure techniques are commonly used in other fields such as diamond production, the method is relatively new to superconductivity research.
The researchers first subjected the material to extremely high pressures, which enhanced its superconducting behavior and raised its transition temperature. While still under pressure, the material was cooled to a carefully chosen temperature, and then the pressure was suddenly released.
This rapid release effectively preserved the enhanced superconducting properties, allowing the material to remain stable even after returning to atmospheric pressure conditions.
“Other researchers have shown that reaching superconductivity at room temperature under pressure is achievable,” Chu said. “Our method shows that you can maintain that state without maintaining pressure.”
A step towards room temperature superconductors
Room-temperature superconductivity at atmospheric pressure remains elusive, but the researchers say this new record is an important step toward that goal. The room temperature was approximately 300 K, a difference of approximately 140 °C from the newly achieved record.
“This discovery has great potential,” Chu said. “We believe that if enough people work on it and given enough time, we can realize the potential.”
Chu and Deng also contributed to a related perspective paper published in PNAS, which was funded by Intellectual Ventures. The paper describes six different approaches, including pressure quenching, that researchers can use to further increase superconducting temperatures.
“Room-temperature superconductivity has been considered the ‘holy grail’ by scientists for more than a century,” said Rohit Prasankumar, director of superconductivity research at Intellectual Ventures. “The UH team’s results show that this goal is closer than ever. However, the distance between the new record set in this study and room temperature is still about 140 degrees Celsius. Closing this gap will require a concerted and intentional effort by the broader scientific community, including not only physicists but also materials scientists, chemists, and engineers.”
