New type of superionic water ice observed for the first time
Hexagonal close-packed phase could exist deep within the planets Uranus and Neptune, contributing to their peculiar magnetic fields The post New type of superionic water ice observed for the first time appeared first on Physics World .
For the first time, scientists have created a new phase of solid superionic ice in the laboratory. French researchers at CEA achieved this by heating and compressing a tiny sample of ultra-pure water using diamond anvil cells and laser heating. This superionic ice features a hexagonal close-packed (hcp) structure with liquid-like hydrogen diffusion through a solid lattice of oxygen atoms.
Such a phase can only exist under extreme pressure (tens to hundreds of GPa) and temperatures above 1000-2000 K. The researchers utilized a unique setup with boron-doped diamond discs to apply pressure while uniformly heating their sample, effectively avoiding temperature gradients common in conventional diamond anvil cells. By employing X-ray diffraction at the European Synchrotron Research Facility, they observed both a new hcp phase of superionic ice and a previously known face-centered cubic (fcc) phase at pressures between 80-229 GPa and temperatures above 1800 K. This discovery adds to the three known superionic phases of water, including the body-centred cubic phase.
The findings could explain the magnetic fields of Uranus and Neptune, which are skewed and off-center relative to their rotation axes. Scientists believe these magnetic fields might be generated by the conductive superionic ice present in the planets' outer layers, rather than the molten iron core on Earth. Further research will aim to pinpoint where this phase is stable within the planets' interiors and examine the transition between different phases under varying pressures and temperatures.
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