Scientists make superionic ice

Abstract

For the first time, scientists have observed an exotic form of water called superionic ice, a feat some thought impossible (Nature 2019, DOI: 10.1038/s41586-019-1114-6). Water ice has 18 possible crystalline arrangements, depending on temperature and pressure. Theoretical work predicted a particularly strange structure would form at very high temperatures and pressures. In this superionic ice, the oxygen atoms are closely packed and locked in place, while protons can move through the lattice, similar to atoms and electrons in a metal. Decades after it was first predicted, scientists have finally observed it in the lab. “You always want to see validation by experiment, and in the case of ice systems, it is very difficult to do so,” says Princeton University’s Roberto Car, a theoretician who has studied superionic ice but was not involved in the new research. In fact, many thought it would be impossible to experimentally create the necessary conditions