Scandium is the only known elemental superconductor to have a critical temperature in the 30 K range. This phase diagram shows the superconducting transition temperature (Tc) and crystal structure versus pressure for scandium. The measured results on all the five samples studied show consistent trends. (Courtesy: Chinese Phys. Lett. 40 107403)
Topics: Applied Physics, Chemistry, Condensed Matter Physics, Materials Science, Superconductors, Thermodynamics
Scandium remains a superconductor at temperatures above 30 K (-243.15 Celsius, -405.67 Fahrenheit), making it the first element known to superconduct at such a high temperature. The record-breaking discovery was made by researchers in China, Japan, and Canada, who subjected the element to pressures of up to 283 GPa – around 2.3 million times the atmospheric pressure at sea level.
Many materials become superconductors – that is, they conduct electricity without resistance – when cooled to low temperatures. The first superconductor to be discovered, for example, was solid mercury in 1911, and its transition temperature Tc is only a few degrees above absolute zero. Several other superconductors were discovered shortly afterward with similarly frosty values of Tc.
In the late 1950s, the Bardeen–Cooper–Schrieffer (BCS) theory explained this superconducting transition as the point at which electrons overcome their mutual electrical repulsion to form so-called “Cooper pairs” that then travel unhindered through the material. But beginning in the late 1980s, a new class of “high-temperature” superconductors emerged that could not be explained using BCS theory. These materials have Tc above the boiling point of liquid nitrogen (77 K), and they are not metals. Instead, they are insulators containing copper oxides (cuprates), and their existence suggests it might be possible to achieve superconductivity at even higher temperatures.
The search for room-temperature superconductors has been on ever since, as such materials would considerably improve the efficiency of electrical generators and transmission lines while also making common applications of superconductivity (including superconducting magnets in particle accelerators and medical devices like MRI scanners) simpler and cheaper.
Scandium breaks temperature record for elemental superconductors, Isabelle Dumé, Physics World