Ammonia Mono Hydrate IV: An Attempted Structure Solution

The mixed homonuclear and heteronuclear hydrogen bonds in ammonia hydrates have been of interest for several decades. In this manuscript, a neutron powder diffraction study is presented to investigate the structure of ammonia monohydrate IV at 170 K at an elevated pressure of 3-5 GPa. The most plausible structure that accounts for all features in the experimental pattern was found in the P2(1)/c space group and has the lattice parameters a=5.487(3) & ANGS;, b=19.068(4) & ANGS;, c=5.989(3) & ANGS;, and beta=99.537(16) deg. While the data quality limits discussion to a proton-ordered structure, the structure presented here sheds light on an important part of the ammonia-water phase diagram.

Automated summary

This manuscript presents a neutron powder diffraction study on the structure of ammonia monohydrate IV at high pressure, providing insights into the ammonia-water phase diagram.