Phase transitions and hydrogen bonding in deuterated calcium hydroxide: High-pressure and high-temperature neutron diffraction measurements

作者：Iizuka Riko^*; Komatsu Kazuki; Kagi Hiroyuki; Nagai Takaya; Sano Furukawa Asami; Hattori Takanori; Gotou Hirotada; Yagi Takehiko

来源：Journal of Solid State Chemistry, 2014, 218: 95-102.

DOI：10.1016/j.jssc.2014.06.010

• Portlandite
• Neutron diffraction
• Hydrogen bond
• High pressure
• Phase transition

In situ neutron diffraction measurements combined with the pulsed neutron source at the Japan Proton Accelerator Research Complex (J-PARC) were conducted on high-pressure polymorphs of deuterated portlandite (Ca(OD)(2)) using a Paris Edinburgh cell and a multi-anvil press. The atomic positions including hydrogen for the unquenchable high-pressure phase at room temperature (phase II%26apos;) were first clarified. The bent hydrogen bonds under high pressure were consistent with results from Raman spectroscopy. The structure of the high-pressure and high-temperature phase (Phase II) was concordant with that observed previously by another group for a recovered sample. The observations elucidate the phase transition mechanism among the polymorphs, which involves the sliding of CaO polyhedral layers, position modulations of Ca atoms, and recombination of Ca-O bonds accompanied by the reorientation of hydrogen to form more stable hydrogen bonds.

• 出版日期2014-10