High pressure chemistry and physics

Diamond anvils at record 4.4 Millions of atmospheres -diamond is reddish at the highest pressures in the center.

Research group Dr. Mikhail Eremets

Our group studies what happens to matter under extremely high pressure. We achieved record static pressures of 440 GPa, which equates to 4.4 million atmospheres and exceeds the pressure in the Earth's inner core (360 GPa). At the heart of our work is a diamond anvil cell. Pressure is generated between the tips of two diamond anvils. This small device can be combined with heating lasers, cryostats, magnets and X-ray sources.  

Extreme pressures can produce dramatic transformations of substances. For instance, we succeeded in converting molecular nitrogen into a polymer, in which all the atoms are connected by single covalent bonds. This polymeric nitrogen material has a similar hardness to diamond. What makes it particularly interesting is its energy content, which is greater than all known non-nuclear substances. At present, we are looking for other forms of polymeric nitrogen which can be synthesized at low pressures, which are easier to work with.

We are currently focusing on dense hydrogen. It is generally assumed that molecular hydrogen will convert into a metal under high pressure. This simplest of metals is considered to be the "Holy Grail" of high pressure physics, because it is expected to act as a high-temperature or even a room-temperature superconductor. This could result in metallic hydrogen gaining a new quantum state as the metallic, superconducting superfluid deuterium. Metallic hydrogen is also significant in astrophysics, as it is one of the main components of giant planets and stars.

We have studied the melting curve of hydrogen and proved that it has a maximum. Our finding supports predictions that metallic hydrogen could well be a quantum liquid at 0 Kelvin, just like liquid helium. We also demonstrated that silane, hydrogen-rich material that has similar properties to pure hydrogen, are superconductive above 70 GPa. Direct metallization of pure hydrogen requires pressures of approximately 400 GPa, which we recently achieved.

Since 2001 our work in this area is being supported by an Advanced Grant of €1.9 million from the European Research Council.