Synchrotron diffraction reveals a hexagonal oxygen lattice in water ice above 200 gigapascals, although the mobile-hydrogen state is inferred rather than directly imaged.
At about 2,350°C—hot enough to melt iron at ordinary pressure—water squeezed to more than two million atmospheres can remain partly crystalline instead of boiling. Its oxygen atoms lock into a lattice while hydrogen nuclei flow freely through it, forming superionic ice; researchers have now reported the first direct observation of a previously predicted hexagonal variety.
Lab Report