Studies on Partially Ordered State of Ice XV

Abstract

Here I discuss a problem of an inconsistency among various experiments and calculations for ice XV, the ordered form of ice VI, i.e., neutron diffraction observations suggest antiferroelectrically ordered structures, which disagree with dielectric measurement and theoretical studies, implying ferroelectrically ordered structures. Our recent neutron diffraction experiments and DFT calculations support a scenario in which several kinds of ordered configuration coexist, which was proposed more than 40 years ago by Kamb. More recently published arguments in terms of this issue are also briefly reviewed.