Metallic Hydrogen has been made in the lab for the first time in history, by a method of squeezing a sample of the element to pressures beyond what exists at the centre of our Planet. The creation of this substance was first predicted way over 80 years ago and was imagined that it could one day lead to superfast computers or in the use of spaceflight.
Two scientists at Harvard University achieved the feat using diamonds to squeeze solid hydrogen at very low temperatures, until the atoms were so packed that they started to share electrons. The shared cloud of electrons indicated a transition into a metallic state, making the hydrogen shiny and electrically conductive at the same time.
Jeffrey McMahon a scientist at Washington State University in Pullman said:
“If this experiment is reproducible, it solves experimentally one of the major outstanding problems in all of physics.”
Also scientist Silvera at Harvard University who made the breakthrough with his colleague Ranga Dias said:
“At a fundamental level, we’re considering the simplest atomic system in the periodic table of the elements, so we would like to understand that system and all of its properties.”
A Long-Sought Material
In 1935, a well-known physicist Eugene Wigner & Hillard Bell Huntington predicted that high pressures of around 25 gigapascals (about 246,000 times atmospheric pressure) could force the normal bonds between solid hydrogen atoms to break down, freeing electrons to move around.
So to put in simple terms, the normally transparent material would become extremely shiny and reflective, and have other properties associated with metals.
“Technically, the definition of a metal is that it conducts a finite amount of electricity even as you cool it toward the lowest possible temperature, absolute zero.”
The research found that the pressure needed for this transition was even much higher — pressures that are likely found only deep at the core of a dense planet.
“There have been dozens of theoretical papers and they all have different critical pressures for when it becomes metallic,”
The researchers found ways to produce higher and higher pressures, yet no one could produce the elusive material.
The problem was: What materials are there on Earth that are strong enough to adequately squish hydrogen atoms?
To answer that question, researchers turned to the strongest material on Earth: diamonds. But even diamonds were cracking under the exceedingly high pressures needed to convert the material.
So, Silvera and his postdoctoral researcher, Ranga Dias, looked for ways to make their diamonds more robust.
“We designed the system so that all the things that can lead to the breaking of a diamond were not there,”
Normally, researchers use diamonds dug from the Earth, which have tiny inconsistencies in their internal structure. The team decided to create tiny anvils from synthetic diamonds, which can be produced without any of these internal in-homogeneities.
“Scientists usually polish these diamonds using a fine powder made of diamonds, but this “can gouge carbon atoms out of the surface and leave defects there,”
Like an initial tear in a piece of paper that makes it more vulnerable to ripping the whole way down, these defects can be failure points where diamonds start to crack.”
Instead, they used a chemical process to etch away a very thin layer of the surface without gouging it.
Finally, the insanely high pressures required in these experiments sometimes cause hydrogen atoms to diffuse into the diamonds, which can also cause cracking. So, the team coated the diamond anvils with alumina, the same material found in sapphire, which prevented the diffusion.
The whole system was cooled to the temperature of liquid helium, about minus 452 degrees Fahrenheit (minus 269 degrees Celsius), and then the diamond anvils squeezed the tiny sample of solid hydrogen.
As the pressure rose, the normally transparent hydrogen molecules morphed into an opaque colour, and then finally became shiny. Follow-up tests confirmed that the material was, indeed metallic. The pressure needed to achieve this transition? 495 gigapascals (71.7 million pounds-per-square inch), or more than the pressure found in Earth’s core.
The researchers predict that metallic hydrogen might be a room-temperature superconductor and could possibly exist, once created, at normal pressures. This would mean it could potentially be used to make superconducting wires that carry electricity vast distances without dissipating any power. The team also speculates that metallic hydrogen is so energy-dense that it could one day be used to create rocket fuel vastly more potent than anything we have at present – revolutionising how we put things in space.
Source: Live Science