The push for practical superconductors

Overview

For 33 years, a mercury-based ceramic held the record for superconductivity at normal atmospheric pressure: 133 Kelvin, set in 1993. Physicists at the University of Houston just pushed that mark 18 degrees higher.

Ching-Wu Chu and Liangzi Deng used a pressure-quench technique to lock a high-pressure superconducting state into the same mercury cuprate after the squeezing stopped. Their result, published in the Proceedings of the National Academy of Sciences, opens a path toward materials that could carry current without loss in ordinary conditions. The temperature still requires deep cooling, but every degree gained shrinks the cost of getting there.

Why it matters

Ambient-pressure superconductors are the kind you can actually build into a power grid; every degree gained brings lossless transmission closer.

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Key Indicators

151 K

New ambient-pressure Tc

The temperature at which the pressure-quenched mercury cuprate begins superconducting at one atmosphere.

+18 K

Gain over 1993 record

The improvement over Schilling's Hg1223 result that stood from 1993 until 2026.

33 yrs

How long the old record held

Time between the original Hg1223 result and the Houston team's break.

1 atm

Operating pressure

Normal atmospheric pressure — the regime that matters for power lines, MRI magnets, and fusion coils.

~140 K

Distance to room temperature

The gap between today's ambient-pressure record and a true room-temperature superconductor.

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People Involved

Paul Ching-Wu Chu

Senior author on the 151K result

Liangzi Deng

Lead author on the 151K paper

Organizations Involved

Texas Center for Superconductivity (TcSUH)

University research center

Lab that produced the 151K result

A University of Houston research center founded the year Chu co-discovered YBCO.

Proceedings of the National Academy of Sciences (PNAS)

Peer-reviewed scientific journal

Publisher of the 151K paper

The official journal of the U.S. National Academy of Sciences, founded in 1914.

Timeline

April 1911 May 2026

9 events Latest: Yesterday

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May 2026
PNAS publishes 151K Hg1223 paper
Latest Publication

Deng and Chu's pressure-quenched Hg1223 result is published in PNAS, formally breaking the 1993 record by 18 degrees.
Yesterday
March 2026
University of Houston announces 151K result
Announcement

UH publicizes the Hg1223 pressure-quench result; a preprint goes up on arXiv ahead of formal publication.
March 10th, 2026
February 2025
Pressure-quench protocol proof-of-concept
Publication

Deng and Chu publish in PNAS a pressure-quench method that locks high-pressure superconductivity in Bi0.5Sb1.5Te3 at ambient pressure.
February 10th, 2025
November 2023
Ranga Dias room-temperature claim retracted
Retraction

Nature retracts Dias's 2023 room-temperature superconductivity paper after misconduct findings, raising the bar for new claims.
November 7th, 2023
December 2015
Sulfur hydride reaches 203K under extreme pressure
Discovery

Hydrogen sulfide superconducts at 203K, but only under about 150 gigapascals of pressure.
December 17th, 2015
May 1993
Hg1223 sets the long-standing ambient-pressure record
Discovery

Schilling and colleagues report HgBa2Ca2Cu3O8+δ superconducting at 133K, a record that holds for 33 years.
May 6th, 1993
March 1987
YBCO breaks the liquid nitrogen barrier
Discovery

Chu and Wu announce YBa2Cu3O7 superconductivity at 93K, the first material that works above liquid nitrogen temperature.
March 2nd, 1987
April 1986
Bednorz and Müller find ceramic superconductivity
Discovery

IBM Zurich researchers report superconductivity at 35K in a lanthanum-barium-copper-oxide ceramic, opening the cuprate era.
April 17th, 1986
April 1911
Onnes discovers superconductivity
Discovery

Heike Kamerlingh Onnes finds that mercury loses electrical resistance at 4.2K.
April 8th, 1911

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

March 1987

YBCO breaks the liquid-nitrogen barrier (1987)

Paul Chu and Maw-Kuen Wu reported YBa2Cu3O7 superconducting at 93 Kelvin, lifting the previous Tc record by more than 50 degrees in a single jump. Their result crossed liquid nitrogen's boiling point of 77K, meaning a superconductor could be cooled by a coolant that costs roughly the same as milk.

Then

Hundreds of labs piled into cuprate research. Tc records fell almost monthly through 1987 and 1988.

Now

Cuprate superconductors became the basis for commercial superconducting magnets and high-current cables used today in MRI, particle accelerators, and grid demonstrations.

Why this matters now

The same Chu lab is now behind the 2026 result, and the same family of cuprates is being squeezed into a new record. Past YBCO results were replicated within weeks; the 151K finding has not yet been independently confirmed.

May 1993

Hg1223 sets the 1993 ambient-pressure ceiling

Andreas Schilling and colleagues at ETH Zurich reported HgBa2Ca2Cu3O8+δ superconducting at 133K at atmospheric pressure, in Nature. The mercury cuprate sat at the top of the ambient-pressure table for 33 years.

Then

Higher Tc values were claimed only under applied pressure, where Hg1223 reaches about 164K.

Now

Practical wire and tape production focused on cuprates with lower Tc but better mechanical properties, leaving Hg1223 mostly a benchmark material rather than an engineered one.

Why this matters now

The 2026 result is the same compound, treated with a new process. The arc of ambient-pressure progress effectively skipped a generation between Schilling and Deng-Chu.

September 2022 to November 2024

The Ranga Dias retractions (2022 to 2024)

Nature retracted two high-profile papers by University of Rochester physicist Ranga Dias claiming room-temperature superconductivity, after data manipulation findings and replication failures. A 2023 paper claiming 21°C superconductivity in a nitrogen-doped lutetium hydride was retracted in November 2023.

Then

Funding agencies tightened review of superconductor claims. Several labs that built equipment to test Dias's recipes reported no superconductivity.

Now

Editors and reviewers now demand more independent verification before accepting room-temperature claims, especially those involving extreme pressure.

Why this matters now

The Dias episode set the standard the Houston result has to clear. PNAS review and Chu's track record help, but independent replication is now the bar that matters.