10 things you may not know about superconductivityApril 8, 2011
2011 marks the 100th anniversary of the discovery of superconductivity, the ability of some materials to conduct electricity with zero energy loss when cooled to extremely low temperatures. This fundamental property of some materials was discovered by Dutch scientist Heike Kamerlingh Onnes at Leiden University.
Around 4 p.m. on April 8, 1911, he cooled mercury to 4.19 degrees Kelvin and found his instruments suddenly measured zero resistivity. He received the Nobel Prize in Physics for this accomplishment two years later.
RELATED: The magnetism—and mystery—of superconductivity: The search for why superconductors work.
Here are 10 things you may not know about superconductivity:
- Onnes was also first to create liquid helium, which he did on July 10, 1908. Helium becomes liquid at 4.2 K and is the coolant of choice for low-temperature superconductors in such modern applications as particle accelerators, superconducting magnets, magnetic resonance imaging and nuclear magnetic resonance.
- Before Onnes created liquid helium, the lowest temperature available to researchers was 14 K from solid hydrogen.
- Onnes originally called his discovery "supra conductivity" but later settled on "superconductivity," the term we use today.
- Onnes' first experiments on resistance at low temperatures focused on gold and platinum. He later switched to mercury because it was easier to get in pure form. Scientific thinking at the time held that extremely pure metals would most likely show zero resistance at liquid-helium temperatures.
- A year after discovering superconductivity in pure mercury, Onnes experimented with a gold-mercury alloy and found it too became superconducting at 4.2 K. He recorded in his notebook that "much of the time spent on the preparation of pure mercury...might therefore have been saved..."
- Onnes' groundbreaking April 8, 1911, experiment also included the first observation of liquid helium's superfluid transition. Superfluids act like liquids with no viscosity, flowing uncontrollably, even up and over the sides of their containers.
- In 1986, Georg Bednorz and Alex K. Mueller of IBM Zurich Research Laboratory discovered a lanthanum-based material that became superconducting at 35 K, a then-record high temperature.
- In 1987 Paul Chu of the University of Houston substituted yttrium in Bednorz and Mueller's compound and produced yttrium-barium-copper-oxide with a transition temperature of 92 K. This material triggered enormous excitement in the scientific community for two reasons: it held out the promise of one day achieving superconductivity at room temperature, and it was the first material that could become a superconductor with liquid nitrogen cooling instead of liquid helium. Compared to helium, nitrogen is vastly more abundant (it makes up nearly four-fifths of the Earth's atmosphere) and is far easier to produce and handle. Scientists often explained the difference by saying, "Liquid helium costs as much as scotch, but liquid nitrogen is cheaper than beer."
- Argonne physicist Alexei Abrikosov shared the 2003 Nobel Prize in Physics for his work on superconductivity theory; he predicted the existence of magnetic vortices in superconductors.
- Five Nobel Prizes in Physics have been awarded for research in superconductivity:
- 1913 — Heike Kamerlingh Onnes for matter at low temperature.
- 1972 — John Bardeen, Leon N. Cooper and J. Robert Schreiffer for theory of superconductivity.
- 1973 — Leo Esaki, Ivar Giaever and Brian D. Josephson for tunneling in superconductors.
- 1987 — Georg Bednorz and Alex K. Mueller for high-temperature superconductivity.
- 2003 — Alexei Abrikosov, Vitaly N. Ginzburg and Anthony J. Leggett for pioneering contributions to the theory of superconductors and superfluids.
BONUS: Argonne National Laboratory holds a number of "firsts" for basic and applied research on superconductors:
- Construction of the world's first superconducting linear accelerator for heavy ions, the Argonne Tandem-Linac Accelerator System.
- First Americans to extrude high-temperature superconducting wire (March 25, 1987)
- First to report the correct structure of the newly discovered yttrium-barium-copper oxide high-temperature superconductor (Applied Physics, June 6, 1987).
- First to successfully put electrical current through yttrium-barium-copper oxide wire: 125 amps/per square centimeter at 77 degrees Kelvin (Sept. 3, 1987).
- The world's first motor based on properties of high-temperature superconductors (Dec. 30, 1987)
— By Dave Baurac