Milestone-Proposal:Discovery of Superconductivity at 93 K in Yttrium Barium Copper Oxide

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Docket #:2017-02

This Proposal has been approved, and is now a Milestone

To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Discovery of Superconductivity at 93 K in Yttrium Barium Copper Oxide, 1987

Plaque citation summarizing the achievement and its significance:

On this site, a material consisting of yttrium, barium, copper, and oxygen was first conceived, synthesized, tested, and -- on 29 January 1987 -- found to exhibit stable and reproducible superconductivity at 93 Kelvin. This marked the first time the phenomenon had been unambiguously achieved above 77 Kelvin, the boiling point of liquid nitrogen, thus enabling more practical and widespread use of superconductors.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

Region 3 Huntsville Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: Region 3 Huntsville Section
Senior Officer Name: Dr. Ebonee Walker

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: Region 3 Huntsville Section
Senior Officer Name: Dr. Ebonee Walker

IEEE section(s) monitoring the plaque(s):

IEEE Section: Region 3 Huntsville Section
IEEE Section Chair name: Dr. Ebonee Walker

Milestone proposer(s):

Proposer name: Dr. James R. Ashburn
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

Wilson Hall (formerly the University of Alabama at Huntsville Science Building) 301 Sparkman Drive Huntsville, AL 35899 GPS Coordinates: +34.72937,-86.64147

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. While the building has undergone substantial renovations since the 1987 discovery, the plaque will be located outside the door that was previously the entrance to the superconductivity lab where the first successful tests on YBCO were performed. Synthesis of the materials spanned this room (where the raw materials were weighed out, mixed, and pressed into pellets) and a room on the second floor that housed the furnace used for heating the materials to the necessary reaction temperature.

Are the original buildings extant?


Details of the plaque mounting:

The plaque will be mounted on an interior hallway wall outside the former lab near an existing plaque commemorating the tenth anniversary of the discovery.

How is the site protected/secured, and in what ways is it accessible to the public?

The intended plaque site is on the University of Alabama in Huntsville campus which is protected by the UAH Campus Police. The building in which the plaque will be installed is secured during nighttime hours but is open to the public seven days a week from 6:30 a.m. to 11:00 p.m.

Who is the present owner of the site(s)?

The University of Alabama in Huntsville

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

January 29th, 2017 marked the 30th anniversary of the discovery of superconductivity above the boiling point of nitrogen by Jim Ashburn, C. J. Torng, and M. K. Wu at the University of Alabama in Huntsville [1]. Surpassing 77 Kelvin had long been a key milestone on the quest for room-temperature superconductivity as it enables significantly less difficult and more cost-effective refrigeration, thus greatly expanding the prospects for more extensive use of superconductivity.

Building on the work of Johannes Georg Bednorz and Karl Alex Müller, who shared the 1987 Nobel Prize in Physics for discovering the first so-called copper oxide superconductor at about 30 Kelvin, Ashburn noted a relationship between the critical temperatures and ionic radii in a series of superconductors ranging from 20 to 40 Kelvin from which he formulated Y(1.2)Ba(0.8)CuO(4-y) [2-8]. The first sample was synthesized by Torng on 28 January 1987 and tested the following day by Ashburn and Wu. The initial AC resistivity test, marked as completing at 2:08 p.m., showed a resistive transition starting near 90 Kelvin and reaching zero (within the precision of the instruments) about 55 Kelvin. A series of seven additional tests on samples made that evening, many reaching zero above 77 Kelvin. Ashburn’s dissertation records, “In all, eight tests on four samples from three separate batches were performed that day. All showed transitions with onsets ranging upwards from 89 K and averaging 93 K and midpoints nearing 93 K" [9]. Superconductivity was subsequently confirmed in these samples via field effect and magnetic susceptibility measurements conducted at the University of Houston the following day [10-13]. The critical superconducting phase, YBa(2)Cu(3)O(7), was subsequently isolated and identified by several groups during the weeks to follow.

Due to a quantum mechanical phenomenon whereby electrons bind in pairs, superconductors display a number of remarkable properties, most notably zero DC resistance while conducting very high density currents, thus enabling the transmission of significant electrical power and the generation of powerful magnetic fields. In addition to high current/high field applications, superconductors also have advantages in signal detection, combining low noise and dispersion with very high sensitivity.

What obstacles (technical, political, geographic) needed to be overcome?

Since 1986, only about 100 structurally unique copper oxide superconductors have been discovered. Finding a new superconductor requires patience, persistence, intuition, and often some measure of luck.

What features set this work apart from similar achievements?

As of the mid-70s, the highest confirmed critical temperature of a superconductor was approximately 23 K, a mark reached over decades, often by fractions of a Kelvin at a time. The 23 K record stood for over a dozen years before Bednorz and Muller shattered it with ~30K superconductivity in LBCO. YBCO, in turn, tripled that level at 93 K. At the same time, it marked a somewhat unique material in that the layered structure was the consequence of the ordering of yttrium and barium and, furthermore, YBCO is characterized as a "self-doped" material, also distinguishing it from LBCO.

The Hor v. Chu case was resolved in April of 2016. In the case, Hor was challenging Chu’s inventorship on both YBCO and its subsequent rare earth analogs. As the proceedings continued, Hor shifted his emphasis to the rare earth variants of YBCO. Here is a link to the final decision in the Hor v. Chu case:

University of Alabama Huntsville settled with University of Houston in 2002(?).

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

[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).

[2] Robert Pool. “Superconductor Credits Bypass Alabama.” Science 5 (August 1988): 655-657.

[3] “What Happened Next? -- Updates on the TJ Retrospective.” Taiwan Today (30 March 2007). <>.

[4] James D. Doss. Engineer's Guide to High-Temperature Superconductivity. New York, Wiley-Interscience, 1989.

[5] Jean Matricon and Georges Waysand. The Cold Wars: A History of Superconductivity. Rutgers University Press, 2003. [6] Bruce Schechter. The Path of No Resistance: The Story of the Revolution in Superconductivity. New York, Simon & Schuster, 1989.

[10] C. W. Chu. “High Temperature Superconductivity.” History of Original Ideas and Basic Discoveries in Particle Physics. Ed. H. B. Newman, T. Ypsilantis. New York: Plenum, 1996. 793.

[11] C. W. Chu. “Superconductivity Above 90 K and Beyond.” Proceedings of the 10th Anniversary HTS Workshop on Physics, Materials and Applications. Ed. B. Batlogg, C. W. Chu, W. K. Chu, D. U. Gubser, K. A. Müller. Singapore: World Scientific, 1996. 17.

[12] C. W. Chu. “High-Temperature Superconducting Materials: A Decade of Impressive Advancement of Tc.” IEEE Transactions on Applied Superconductivity 7.2 (1997): 80-89.

[13] While the above three sources confirm the date and location of the discovery, their descriptions of how the critical YBCO composition was conceived are in error. See James Ashburn. Discovery of Superconductivity at 93 K in YBCO: The View from Ground Zero. <>.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

[7] Alabama Historical Commission Marker: Superconductivity Discovery. Wilson Hall. Dedicated 29 January 2012. <>. Media:07_AlabamaHistoricalCommissionMarker.jpg

[8] The University of Alabama in Huntsville Marker: Superconductivity Advance. Wilson Hall. Dedicated 29 January 1997. Media:08_UAHMarker-a.jpg Media:08_UAHMarker-b.jpg Media:08_UAHMarker-c.jpg Media:08_UAHMarker-d.jpg

[9] J. R. Ashburn. Yttrium Barium Copper Oxide: The Formulation and Magnetic Properties of a 93 K Superconductor. Huntsville, AL: UAH (December 1990). Media:09_AshburnDissertationCh2.pdf.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.