High-pressure responses of alkali metal hydrogen carbonates, RbHCO3 and CsHCO3: Findings of new phases and unique compressional behavior
High-pressure responses of alkali metal hydrogen carbonates, RbHCO3 and CsHCO3: Findings of new phases and unique compressional behavior
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碱金属碳酸氢盐、RbHCO3 和 CsHCO3 的高压响应：新相和独特压缩行为的发现
DOI：
10.1016/j.jssc.2019.121139
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发表时间：
2020
影响因子：
3.3
通讯作者：
Kagi Hiroyuki
中科院分区：
文献类型：
--
作者：
Iizuka-Oku Riko;Gui Weibin;Komatsu Kazuki;Yagi Takehiko;Kagi Hiroyuki
rbhco3和cshco3的高压响应通过situRaman光谱、x射线和中子衍射观察进行了表征。rbhco3在~0.5 GPa和室温下表现为单斜相（IV相）和三斜相（V相）高压相。增加压缩诱导了特定细胞参数（ain相IV或cin相V）的独特行为，在~1 GPa时首先增加，然后减少，可能是由于Rb+的重排和有序的（HCO3−）2二聚体的重新配置。测定了rbdco3在第四相中的氘位置。氢键保持中等强度，并且可能不影响相变，尽管伴随二聚体的无序和有序。cshco3在5 GPa以下没有结构变化，表明其环境相（与KHCO3的四相同结构）在高压下已经稳定。结构稳定性似乎与阳离子大小有系统的关系。
High-pressure responses of RbHCO3and CsHCO3were characterized byin situRaman spectroscopy and X-ray and neutron diffraction observations. RbHCO3exhibited a monoclinic (phase IV) and a triclinic (phase V) high-pressure phase at ~0.5 GPa and room temperature. Increasing compression induced unique behavior in a specific cell parameter (ain phase IV orcin phase V), which first increased, and then decreased at ~1 GPa, likely owing to the rearrangement of Rb+and reconfiguration of the ordered (HCO3−)2dimers. Deuterium positions in phase IV of RbDCO3were determined. The hydrogen bonding remained moderately strong, and possibly did not affect the phase transition despite the accompanying disordering and ordering of the dimers. CsHCO3showed no structural change up to 5 GPa, suggesting that its ambient phase (isostructural to phase IV of KHCO3) was already stable at high pressure. The structural stability appeared to be systematically related to the cation size.