When current flows in materials, it generates heat because of the resistance it encounters. This causes the materials to get hot and this has to be accounted for when designing electrical systems in order to avoid fires or meltdowns. This heat is also a major source of energy dissipation and loss. Superconductors are materials that do not have any resistance to the flow of current and thus can cut down energy consumption tremendously.
Superconductivity was first discovered more than a century ago in 1911 but the catch was that those materials only became superconductors at extremely low temperatures close to absolute zero (at below 4K which is around -269C) that could only be reached using liquid helium. This made it impractical for everyday use and the search was on to see if materials could be found that would work at higher temperatures, with the ultimate goal being room temperature superconductivity. If that is achieved, it would enable a whole host of revolutionary new technology.
The superconducting temperatures crept higher but seemed to plateau at about 30K (−243C). A big breakthrough came in 1986 with the discovery of certain ceramic materials that were superconducting at 138 K (−135C), which could be reached much more cheaply using liquid nitrogen. Temperatures started creeping higher again but slowly but now a scientific group has claimed that they have reached a new record temperature of 250K (-23C), which is a big jump from the previous record of 203K (-70C). This is a temperature that is achieved in winter in areas near the poles. The material also has to be at an extremely high pressure of 170 GPa which is about 1,677,769 times atmospheric pressure.
Actually three conditions usually have to be met before a material is declared to be a true superconductor.
There are three tests, reports MIT Technology Review, that are considered the gold standard for superconductivity, and the team has only achieved two: the drop in resistance below a critical temperature threshold, and replacing elements in the material with heavier isotopes to observe a corresponding drop in superconductivity temperature.
The third is the Meissner effect, which is the name given to one of the signatures of superconductivity. As the material passes below the critical temperature and transitions into superconductivity, it ejects its magnetic field.
The team has yet to observe this phenomenon because their sample is so small – well below the detection capabilities of their magnetometer. However, the transition into superconductivity has an effect on the external magnetic field, too. It’s not a direct detection, but the team was able to observe this effect.
One of the problems with commercial applications of these high temperature superconductors is that the materials are brittle and not as malleable as copper wire. This would constitute another hurdle to be overcome but it is still a major advance. Another is that we would need to lower the pressures required to something closer to atmospheric pressure. So there is still a long way to go.
The paper is currently being peer reviewed.