Superconductors are hailed as the key to driving next-generation electronics and energy technologies—such as zero-power electronic devices (for achieving ultra-fast computation and energy-saving data centers), next-generation energy grids (creating lossless smart power transmission systems), quantum and advanced technologies (speeding up the development of quantum computers and nuclear fusion reactors)—but the prerequisite is that they don’t have to be so “difficult to handle.”
To bring materials into a superconducting state, which means achieving almost zero electrical resistance and almost zero energy loss in current transmission, it usually requires extremely harsh conditions: extremely low temperatures, extremely high pressures, or a combination of both.
In other words, even though we know that superconducting technology could bring revolutionary applications to our daily lives—such as creating heatless ultra-fast electric vehicle charging cables, lossless national power grids, or powerful magnetic levitation trains—we cannot afford to equip every vehicle or wire with massive liquid nitrogen cryogenic equipment, or even the kind of high-pressure “Diamond Anvil Cell” that can be found deep underground.
However, a research team led by physicists at the University of Houston in the United States has recently achieved a new world record for the highest superconducting transition temperature (Tc) to date under ambient pressure conditions, taking a significant step toward developing superconductors that can operate under “everyday conditions.”
This breakthrough has significantly increased the transition temperature of ambient pressure superconductors by nearly 20℃, reaching -122.15℃ (about 151K).
While -122.15℃ may still sound cold, compared to the conditions where early superconductors had to approach absolute zero (-273.15℃) to operate, this is already a quite “warm” breakthrough. More importantly, this breakthrough breaks the stalemate that has been maintained in the field for decades.
“This is a crucial step towards practical room temperature, ambient-pressure superconductors,” said Hua Zhou, a physicist at the Argonne National Laboratory in the United States. “Because this material can maintain its superconductivity at ambient pressure, scientists can use commonly available experimental instruments to study it and begin developing related technologies that can operate under everyday environmental conditions.”
The material involved in this breakthrough belongs to the well-known cuprate superconductors, with a microstructure consisting of layers of copper oxide interspersed with other metal oxide layers, including the chemical elements mercury (Hg), barium (Ba), and calcium (Ca), abbreviated as Hg1223.
In fact, since its introduction in 1993, Hg1223 has been holding the record for the highest Tc under ambient pressure conditions at 140.15℃ (about 133K). However, in the thirty years since then, the advancement of ambient pressure superconducting transition temperatures has nearly stagnated.
To break through this barrier, the University of Houston team employed a key physical processing technique called “pressure-quenching.”
1. Applying Extreme Pressure:
Researchers first applied pressures as high as 30 gigapascals (GPa) to the Hg1223 material using a diamond anvil cell—a pressure equivalent to 300,000 times the atmospheric pressure at sea level. The high pressure forces the atoms in the lattice to compress tightly and reorganize into a structure with higher superconducting potential.
2. Rapidly Releasing the Pressure:
Subsequently, the research team rapidly released this high-pressure condition within a short timeframe, “locking” the material in a specific metastable state.
What is a metastable state? The most classic example is the diamond we are familiar with. Carbon atoms deep in the earth’s mantle form diamond crystals under high temperature and pressure, and when brought to the surface in ambient pressure conditions, the crystal structure formed under high pressure is “frozen” and preserved.
During the “pressure-quenching” process, rapid pressure release induces unique microscopic lattice strain and structural rearrangement within the material. Researchers point out that it is these microstructures preserved in the metastable state that allow Hg1223 to retain and exhibit superconductivity at higher temperatures even after the pressure drops back to normal ambient pressure.
The research team then used the Advanced Photon Source (APS) at the Argonne National Laboratory to analyze the material, confirming its superconducting properties. The APS is a powerful synchrotron X-ray light source that can observe microscopic structural changes within materials with extreme precision.
While Hg1223 is not the superconductor with the highest transition temperature in history if looking solely at the “highest temperature,” the current record holder is lanthanum decahydride (LaH₁₀), which can maintain a superconducting state at -13.15℃ (close to household freezer temperatures). However, it requires up to 190 gigapascals of extremely high pressure to operate—pressure equivalent to the extreme environment of the Earth’s outer core, which is nearly impractical for widespread applications in real life.
In comparison, through “pressure-quenching,” Hg1223 has successfully broken free from the constraints of high-pressure equipment, achieving a significant leap toward “ambient-pressure operation.”
The ultimate dream of physicists is to create “room-temperature, ambient-pressure” superconducting materials. If this goal is achieved, it will revolutionize human energy and electronic technologies.
Of course, there is still a long way to go before these applications are truly realized, but each new breakthrough pushes humanity closer to this goal.
This research was published in March in the Proceedings of the National Academy of Sciences.