Brucite, Mg(OH)₂ (P3̅m1, Z = 1), is a prototype material for studying hydrogen bonds in solid hydroxides. In this study, substitutional effects of fluorine (F) on the hydrogen-bonding geometries of hydrogenated and deuterated brucite were investigated under ambient conditions and at high pressure using combined experimental methods of neutron powder diffraction, Raman spectroscopy, and infrared (IR) spectroscopy. Under ambient conditions, neutron powder diffraction results showed that F substitution decreased the donor–acceptor distance and increased the hydroxyl covalent bond lengths of both hydrogenated and deuterated brucite, strengthening the hydrogen bond. Red shifts of the hydroxyl stretching modes also indicated an elongation of d(O–H) and d(O–D). High-pressure neutron diffraction experiments were performed on Mg(OH)_1.81F_0.19 and Mg(OD)_1.74F_0.26 up to 7.04 and 10.02 GPa, respectively. For both samples, changes in the hydrogen-bonding geometries did not indicate hydrogen-bond strengthening under high pressure. Compared with Mg(OD)₂, the doping of F suppressed the increase of the hydroxyl covalent bond length, the hydrogen-bond angle, and the cone angle, inhibiting pressure-induced hydrogen-bond strengthening. High-pressure Raman and IR absorption spectroscopic measurements on Mg(OD)₂ and Mg(OD)_1.79F_0.21 up to 9.7 and 13.7 GPa confirmed that F substitution restrains pressure-induced hydroxyl elongation.

中文翻译：

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氟掺杂水镁石中氢键的高压行为


水镁石，Mg（OH）₂ （P3̅m 1，Z = 1），是研究固体氢氧化物中氢键的原型材料。在本研究中，使用中子粉衍射、拉曼光谱和红外 （IR） 光谱的组合实验方法，在环境条件和高压下研究了氟 （F） 对氢化和氘化水镁石氢键几何形状的取代效应。在环境条件下，中子粉衍射结果表明，F 取代缩短了氢化和氘化水镁石的供体-受体距离，增加了羟基共价键长度，增强了氢键。羟基拉伸模式的红移也表明 d（O-H） 和 d（O-D） 的伸长。对 Mg（OH）_1.81F_0.19 和 Mg（OD）_1.74F_0.26 分别达到 7.04 和 10.02 GPa 进行了高压中子衍射实验。对于这两个样品，氢键几何形状的变化并不表明高压下的氢键强化。与 Mg（OD）₂ 相比，F 的掺杂抑制了羟基共价键长度、氢键角和锥角的增加，抑制了压力诱导的氢键强化。对 Mg（OD）₂ 和 Mg（OD）_1.79F_0.21 至 9.7 和 13.7 GPa 的高压拉曼和红外吸收光谱测量证实，F 取代抑制了压力诱导的羟基伸长。