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Icons of Progress
 

High-Temperature Superconductors

IBM100 High-Temperature Superconductors iconic mark
 

In the summer of 1972, a bright and energetic earth sciences student named Georg Bednorz walked into the IBM Research Laboratory in Zurich, Switzerland. He spent just three months in the lab’s physics department before returning to University to finish his education, but the experience he gained and the relationship he formed with IBM researcher, Alex Müller, would change Bednorz’s life, and the world.

Several years later, Bednorz returned to the lab where he was originally exposed to perovskites—a large family of crystalline oxides. Müller had been researching perovskite compounds for nearly 15 years, and he encouraged Bednorz to focus his doctoral research on the construction and characterization of this material class. Even though they had very different personalities and interests, the two would stay close for the next 10 years before beginning an intense collaboration in 1983 searching for high-temperature superconductivity in oxides.

Superconducting materials hold a special place in the imagination of scientists. Electrical currents, once set in motion, flow in perpetuity in a closed loop of superconducting material. It is thought to be the closest approximation of perpetual motion found in nature. Its potential applications for science and industry are as vast as they are alluring. The only problem was that previously identified superconducting materials, generally of a metal or alloy, required extremely low temperatures before they exhibited the desired properties—condemning them to an existence inside textbooks and highly specialized studies.

The challenge was to find a material that would exhibit superconductivity at usable temperatures. Müller and Bednorz hypothesized and tested extensively to no avail. It was not until 1985 when Bednorz read a French article in which an oxide with perovskite structure was shown to exhibit conductivity within Bednorz and Müller’s target temperature range. One year later, in 1986, Müller and Bednorz created a brittle ceramic compound—extremely controversial as ceramics are generally considered insulators—that was superconductive at the highest temperature ever recorded: 30 Kelvin (–243.15 degrees Celsius, –405.67 degrees Fahrenheit). This was the first time ceramics were even remotely considered as viable candidates for use as superconductors. Bednorz recalled, “Alex and I were really excited, as repeated measurements showed perfect reproducibility and an error could be excluded. Compositions as well as the thermal treatment were varied and within two weeks we were able to shift the onset of the resistivity drop to 35 K.”

The scientific community shook. Scientists from across the world reproduced, modified and improved Müller and Bednorz’s process at a breakneck pace—reigniting global interest in superconductors and accelerating superconductor development. Based on Müller and Bednorz’s discovery, scientists soon developed materials that achieved superconductivity above 77 Kelvin, the boiling point for liquid nitrogen, a relatively cheap and widely accessible coolant. Using liquid nitrogen to reach superconductivity opened the door for a multitude of practical applications. In 1987, Müller and Bednorz were awarded the Nobel Prize in Physics. This recognition is generally bestowed upon innovators years after their discovery, but in this instance, the IBMers received its highest honor just one year after their breakthrough.

The social and commercial benefits stemming from superconductors are just now reaching the market, ranging from use in smart power grids, metal processing, wind power and high-speed trains—but we remain years away from broader adoption. While we still have much to learn from superconductors, their promise is apparent and their potential seems limited only by the imagination of science.

 

The team

Selected team members who contributed to this Icon of Progress:

  • K. Alexander Müller IBM Fellow and Nobel Laureate
  • J. Georg Bednorz IBM Fellow and Nobel Laureate