In the fall of 2020, scientist broke records in the domain of physics. They created a material with the ability to superconduct electricity at the highest temperature yet: almost room temperature.
What is a superconductor?
A superconductor is a substance that conducts electricity with no resistance. This allows current to flow without any energy loss. Having no resistance would mean that an electric current flowing through a superconductive wire could conduct electricity indefinitely with no power source. Unfortunately, most materials must be at extremely low temperatures in order to become superconductive. Because of this they’re impractical for most uses.
Electrical resistance in wires occurs when freely flowing electrons bump into the atoms that make up the wire. At low temperatures, however, electrons start to create vibrations in the arrangement of atoms of the wire (the atomic lattice). This in turn, pulls the electrons into pairs called Cooper Pairs. Different quantum rules govern these pairs that allow them to stream through the atomic lattice without bumping into the atoms. That is to say, there is no resistance. As the temperature of the superconductor rises, however, the Cooper Pairs break apart and start moving randomly, creating resistance.
Magnetic fields occur in magnetically charged materials or as a result of moving electrical charges or currents. When the temperature of the material drops below the point that it becomes a superconductor, the magnetic field lines are expelled and have to pass around the super conductor material. This means that the repulsive force of the magnetic field can be used to levitate the material. Imagine a train created with superconductors; it could levitate and be entirely frictionless!
In 2019, scientists achieved the previous record temperature for a super conducting material. They reported superconductivity at a temperature of -13°C at a pressure of 170 gigapascals (about 1.7 million atmospheres).
A team of physicists at the University of Rochester in New York have broken the record and created a material that can conduct electricity at temperatures of up to 15°C! The material was formed by squeezing the elements between the tips of two diamonds and hitting the substance with a laser light to induce chemical reactions. However, there is one serious limitation: it is only superconductive at extremely high pressures. More specifically the pressure must be 267 gigapascals — 2.6 million times atmospheric pressure at sea level. That’s about 75% as much as the pressure found at the centre of the Earth! This means that for the moment, this substance has no practical uses.
This new material is made of sulphur, hydrogen and carbon. It is the first time that scientists have recorded this level of superconductivity in a compound of three elements, yet the fine details of the structure allude them. The exact chemical formula and the arrangement of atoms are unknown. This is because hydrogen is too small to show up in images and as you go to higher pressures, the sample size gets smaller and therefore it’s harder to observe its structure. Once they can figure out this structure, more exploration of this incredible material and it’s features will be done.
Practical Uses of Superconductors
Room-temperature superconductors at atmospheric pressure could have vast applications. Current uses of superconducting electromagnets include maglev trains, MRI machines, particle accelerators and other advanced technologies, including early quantum supercomputers. It is costly to maintain materials at these low temperatures and high pressures. Advancements in superconductors would improve these technologies. This would reduce energy loss due to resistance. However, so far, scientists have created only very small amounts of this material at extremely high pressure. Therefore, practical applications are still far in the future.