High-pressure behaviors of hydrogen bonds in fluorine-doped brucite

He, X.*; Kagi, Hiroyuki*; Komatsu, Kazuki*; Sano, Asami   ; Abe, Jun*; Fukuyama, Ko*; Shimmei, Toru*; Nakano, Satoshi*

Brucite, Mg(OH), is a key material for studying hydrogen bonds in solid hydroxides. This study explored how fluorine (F) substitution affects hydrogen-bonding in hydrogenated and deuterated brucite under ambient and high-pressure conditions using neutron powder diffraction, Raman, and IR spectroscopy. At ambient conditions, F substitution shortened donor- acceptor distances and elongated hydroxyl bonds, strengthening hydrogen bonds, as evidenced by red shifts in hydroxyl stretching modes. High-pressure experiments showed that F doping suppressed pressure-induced hydrogen-bond strengthening, reducing changes in hydroxyl bond length, bond angle, and cone angle. Spectroscopic measurements confirmed that F substitution limits pressure-induced hydroxyl elongation.