Normally superconductivity (the ability of some materials to conduct electrical current without resistance or loss of energy) is obtained at tens or hundreds of degrees below zero. Since its discovery more than a century ago, in 1911, superconductivity has come to play an important role in many modern technologies, such as maglev trains and MRIs, but its usefulness has certainly been limited by the imperative of having to achieve extremely cold temperatures. Now, a team of scientists from the University of Rochester (USA ) has achieved it at 15 ° C (breaking the previous record of -23 ° C) with a compound of hydrogen, sulfur and carbon.
The research aims to overcome one of the main obstacles in expanding the uses of superconducting materials . These materials do not have electrical resistance and expel a magnetic field, but since they normally only work at temperatures below 140 ° C, they are not sustainable to maintain: it is very expensive.
“Due to the limits of low temperature, materials with such extraordinary properties have not transformed the world in the way that many might have imagined,” says physicist Ranga Dias, leader of the work published in the journal Nature. “However, our discovery will break down these barriers and open the door to many potential applications.”
What exactly properties does superconductivity have?
On the one hand, zero resistance. Generally, the flow of an electric current encounters some degree of resistance; the higher the conductivity of a material, the less electrical resistance it has and the current can flow more freely. On the other, we talk about the Meissner effect, in which the magnetic fields of the superconducting material are expelled, which forces the magnetic field lines to deviate around the material. Thus, if we place a small permanent magnet on a superconducting material, the repulsive force of these magnetic field lines will make it levitate, as we can see in the image that accompanies this article.
Holy Grail
Dias explains that developing materials that are superconducting, without electrical resistance and without magnetic field expulsion at room temperature, is the “holy grail” of condensed matter physics. These materials, according to the expert “can definitely change the world as we know it.”
How would our world change?
To begin with, electricity could be stored or transmitted over great distances; we would have more powerful maglev trains or other futuristic transportation solutions and improved medical imaging technologies. The distinctive magnetic fields that superconductors create would be a game changer for scientific instruments, medical imaging devices, and frictionless transport devices.
To achieve this, the scientists combined hydrogen with carbon and sulfur to photochemically synthesize carbonaceous sulfur hydride derived from simple organics in a diamond anvil cell, a research device used to examine minute quantities of materials under extraordinarily high pressure . It is encouraging that Dias’ superconductors do not require rare or expensive components. “Hydrogen is the lightest material and the hydrogen bond is one of the strongest”, clarifies the expert. Fortunately, it is also the most common element in the universe, and carbon and sulfur are also quite abundant.
Finding a way to produce the superconducting material at much lower pressures will be key to producing it in useful quantities at a reasonable cost, the researchers say.
Referencia: Ranga Dias et al. Room-temperature superconductivity in a carbonaceous sulfur hydride , Nature (2020). DOI: 10.1038/s41586-020-2801-z
