One of the most interesting things about space exploration is how many technologies affect our ability to go further. New technologies that may not be immediately deployed in space can ultimately have profound long-term effects. On the other hand, everyone knows that some technologies will instantly change the game. Superconductors, or materials that have no electrical resistance, are one of the technologies that have the potential to change the game. However, obstacles to their practical application have limited their applicability to a relatively small subset of applications, such as magnetic resonance imaging devices and particle accelerators. Another major hurdle to the widespread use of superconductors has now been removed – a laboratory at the University of Rochester (UR) has just developed a laboratory that works at near room temperature. The big restriction is that it must be under a pressure similar to that in the Earth's core.
The superconductor that the UR laboratory, run by Dr. Ranga Dias operated, developed, is based on hydrogen. While this might not seem like an intuitive place to look for a material with no resistance, hydrogen compounds have long been on the superconducting roadmap. In the past, researchers have focused on finding "hydrides" or combinations of hydrogen with another material in order to find a mixture that could be superconducting at high temperatures, albeit at extremely high pressures.
Video about the possible effects of room temperature and pressure superconductors.
Photo credit: Isaac Arthur
The novel UR laboratory added a third element to the mixture – carbon. Carbon was mixed with hydrogen sulfide, which had already established itself as a good high-temperature superconductor. As with many groundbreaking scientific experiments, they had to make small changes to this mix to find a system that worked. In this case, each of these tweaks could prove to be quite expensive.
The most important component of the material mix is hydrogen. If you add too little hydrogen you will not get a superconducting reaction. If you add too much, the material will only become superconducting at pressures that may not be achievable in the laboratory. The key is to find a sweet spot where the material becomes superconducting at pressures that can be achieved with a tool known as a diamond anvil. This anvil, although it can generate the highest pressure known to man, can also break if its pressure limit is exceeded. Each costs more than $ 3,000, so it's likely that the graduate students who did the work had many sleepless nights calculating the literal cost of their failure.
Graphic representation of a diamond anvil system as it was used to manufacture the new superconductor.
Photo credit: Wikipedia user Tobias1984
In the end, however, they succeeded. The material they have developed can superconduct at a temperature of 15 degrees Celsius and at 267 GPa 75% of the 330 GPa in the Earth's core. Fortunately, this pressure doesn't consistently break your diamond anvils.
However, at such a high pressure it means that this particular material is unusable for commercial applications. However, there is still a lot to learn. A key feature of the material that has not yet been discovered is its crystal lattice structure. The lattice structure is an important component in understanding how something is superconducting. Metallic hydrogen is known to be difficult to examine for lattice structure because it is too small to show up using traditional techniques. This misunderstanding makes it impossible to know the exact chemical formulation of the material that was formed when the compound was placed under such high pressure.
Microscopic images of the stages in the generation of atomic molecular hydrogen: transparent molecular hydrogen (left) at around 200 GPa, which is converted to black molecular hydrogen, and finally reflective atomic metallic hydrogen at 495 GPa. This material is the key to understanding the structure of the novel superconductor.
Photo credit: Isaac Silvera
Carbon could be key to removing the need for that pressure. Lattice structures formed with carbon are very stable compared to the light bonds that hydrogen forms. If materials scientists are able to use this carbon structure in a way that allows electrons to move freely at lower pressures, it could result in a superconductor at room temperature and pressure.
In the meantime, theorists and experimenters will be in a race to develop new ideas and materials based on these findings. Almost every article on paper contains enthusiastic quotes from research professionals who were not part of the original work. When scientists come together to praise the work of their peers, it is a good sign that a real milestone has been reached. With a little more work and 100 years of research, we might finally be able to fully apply superconducting materials in space exploration and beyond.
SciShow – The first superconductor at room temperature!
Quanta Magazine – Superconductivity achieved for the first time at room temperature
Nature – The first superconductor at room temperature excites – and confuses – scientists
Header Image Credit: J. Adam Window / University of Rochester