High-pressure responses of RbHCO₃ and CsHCO₃ were characterized by in situ Raman spectroscopy and X-ray and neutron diffraction observations. RbHCO₃ exhibited 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 (a in phase IV or c in phase V), which first increased, and then decreased at ∼1 GPa, likely owing to the rearrangement of Rb⁺ and reconfiguration of the ordered (HCO₃⁻)₂ dimers. Deuterium positions in phase IV of RbDCO₃ were determined. The hydrogen bonding remained moderately strong, and possibly did not affect the phase transition despite the accompanying disordering and ordering of the dimers. CsHCO₃ showed 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.

RbHCO ₃和CsHCO ₃的高压响应通过原位拉曼光谱，X射线和中子衍射观察进行表征。RbHCO ₃在〜0.5 GPa和室温下表现出单斜晶相（IV相）和三斜晶相（V相）高压相。增加压缩诱导特定小区参数独特行为（一个在第四阶段或Ç在第五阶段），该第一升高，然后在〜1 GPA降低，可能由于Rb的重排⁺和重新配置所述有序（HCO的₃ ⁻）_2个二聚体。RbDCO ₃ IV期中的氘位置被确定。尽管伴随有二聚体的无序和有序，但氢键仍保持中等强度，并且可能不影响相变。CsHCO ₃在最高5 GPa时无结构变化，表明其环境相（KHCO _3的IV相与结构相异）在高压下已经稳定。结构稳定性似乎与阳离子的大小有系统的关系。