Milestones:High-Temperature Superconductivity, 1987

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Houston, TX
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High-Temperature Superconductivity, 1987


On this site in 1987, yttrium-barium-copper-oxide, YBa2Cu3O7, the first material to exhibit superconductivity at temperatures above the boiling point of liquid nitrogen (77k), was discovered. This ushered in an era of accelerated superconductor materials science and engineering research worldwide, and led to advanced applications of superconductivity in energy, medicine, communications, and transportation.

Street address(es) and GPS coordinates of the Milestone Plaque Sites

Science and Research Building 1, University of Houston Closest street address: 3577 Cullen Blvd., Houston Texas 77004, U.S.A. GPS coordinates: +29° 43' 21.9318

Details of the physical location of the plaque

The plaque will be mounted on a wall in the ground floor entrance hall

How the intended plaque site is protected/secured

The intended plaque site is on the University of Houston campus, which is protected by the UH Department of Public Safety (Police Department, Security Services, and Fire Marshal). The building in which the plaque will be installed is locked during non-business hours. The intended plaque site is accessible to the public during University business hours, 8 a.m. - 5 p.m., Monday - Friday, excluding University holidays. Visitors will not need to go through security, make an appointment, or contact anyone in order to visit the plaque during business hours.

Historical significance of the work

January 2012 marked the 25th anniversary of the discovery of superconductivity above the liquid-nitrogen temperature by Paul C.W. Chu and coworkers at the University of Houston[1]. Breaking the liquid nitrogen temperature barrier of critical temperature is a great milestone in the journey toward room temperature superconductivity, and is an impressive achievement in modern science. This discovery made application possibilities cost-effective, practical and closer to consumer needs to a degree never imagined before. As one of the great achievements of the century, this invention was invited as a contribution to the White House National Millennium Time Capsule at the National Archives in 2000 [2]. Paul Chu was awarded the National Medal of Science in 1988 [3]. Superconductors differ from usual conductors fundamentally in how electrons and therefore electric currents, transport in them, giving rise to performance benefits. Exceptional properties resulting in performance benefits include zero DC resistance (very low resistance at high frequencies), very high current carrying density, and very low signal dispersion, exclusion of magnetic fields, and very high sensitivity to magnetic fields when put in the superconducting quantum interference device configuration. Zero resistance and high current density have major importance in high efficient power transmission and have technological benefits, for example in powerful electromagnets and powerful miniature motors. High sensitivity of superconductors to magnetic fields has made superior sensing applications possible, and magnetic field exclusion has made superconducting levitation a possibility. Further, superconductivity has made high speed computing and signal transmission possible that is well beyond the theoretical limit reachable by the semiconductor technology. Prior to 1987, all superconducting materials had lower critical temperatures (Tc’s) and therefore functioned only at temperatures near the boiling point of liquid helium (4.2 K) or liquid hydrogen (20.28 K), with the highest being Nb3Ge at 23 K. This made refrigeration used to cool the material to below the critical temperature extremely costly and technologically challenging, limiting superconducting applications only to specialized critical needs. Inspired by the work of Georg Bednorz and Karl Mueller on high temperature superconductivity (HTS), Paul Chu and his associates at the University of Houston discovered in 1987 that YBCO (Yttrium1- Barium2-Copper3-Oxygen7) and iso-structural RBCO (Rare-earth1-Barium2-Copper3-Oxygen7) have a Tc of 93 K. Paul Chu’s group holds the current Tc-record of 164 K in the mercury barium based cuprate superconductor under pressure.[4] Their work led to a rapid succession of new high temperature superconducting materials, ushering in a new era in material science, chemistry and technology. YBCO was the first material to become superconducting above 77 K, the boiling point of liquid nitrogen, and marked the beginning of the discovery of a series of high temperature superconducting materials. Aside from being the first liquid nitrogen high temperature superconductor, YBCO possesses superior superconducting and physical properties to those of current high temperature superconductors. Among numerous application possibilities [5], YBCO receiver coils in NMR-spectrometers have improved the resolution NMR spectrometers by a factor of 3 compared to that achievable with conventional coils. YBCO coated conductor tapes of length have been produced by depositing YBCO on flexible metal tapes with buffer oxide layers that can have significant applications in power generation, transmission and storage. Advances in high temperature superconductors in general promise more compact, less costly and superior MRI-imaging, Magneto- Encephalography (MEG), Magnetic Source Imaging (MSI) and Magnetocardiography (MCG), noninvasive diagnostics. Use of high temperature superconductors in industry is expected to reduce power consumption significantly, and use of powerful HTS magnets in water remediation, material purification and industrial processing are being demonstrated. HTS filters are already widespread in cellular communication systems. Today continuing research and development in HTS could lead to new technologies ranging from clean abundant energy from nuclear fusion, to advanced medical technology, to computing at speeds faster than ever before.

Features that set this work apart from similar achievements

Significant references

[1] M. K. Wu, J. R. Ashburn, C. J. Torng, P. H. Hor, R. L. Meng, L. Gao, Z. J. Huang, Y. Q. Wang, and C. W. Chu (1987). "Superconductivity at 93 K in a New Mixed Phase Y-Ba-Cu-O Compound System at Ambient Pressure,” Phys. Rev. Lett. 58 (9): 9089 (1987); P. H. Hor, R. L. Meng, Y. Q. Wang, L. Gao, Z. J. Huang, J. Bechtold, K. Forster and C. W. Chu, “Superconductivity above 90 K in the Square-Planar Compound System YBa2Cu3O7 with A = Y, La, Nd, Sm, Eu, Gd, Ho, Er and Lu,” Phys. Rev. Lett, 58, 1891 (1987).

[2] National Millennium Time Capsule,

[3] National Science Foundation - The President's National Medal of Science 1988,

[4] L. Gao, Y. Y. Xue, F. Chen, Q. Xiong, R. L. Meng, D. Ramirez, C. W. Chu, J. H. Eggert and H. K. Mao, “Superconductivity up to 164 K in HgBa2Can-1CunO2n+2-δ (n = 1, 2 and 3) under QUASI-Hydrostatic Pressures,” Phys. Rev. B, (Rapid Communications) 50, 4260 (1994).

[5] Booklet, Superconductivity: Present and Future Applications (2008), Coalition for the Commercial Application of Superconductors (CCAS) and IEEE Council on Superconductivity (IEEE CSC), 35 pages (2008). See U.S. Patent 7,056,866, “Superconductivity in square-planar compound systems,” C. W. Chu, filed March 26, 1987; awarded June 6, 2006

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