Evidence of a phase transition of RbHCO3 from high-resolution solid-state 13C and 87Rb NMR by comparison with KHCO3 |
| |
Authors: | Odin Christophe |
| |
Institution: | Groupe Matière Condensée et Matériaux, UMR 6626 au CNRS, Université Rennes I, Campus de Beaulieu, 35042 Rennes Cedex, France. christophe.odin@univ.rennes1.fr |
| |
Abstract: | A variable-temperature high-resolution 13C and 87Rb solid-state NMR study of powder rubidium hydrogencarbonate, RbHCO3, is presented for the first time. At ambient temperature, RbHCO3 is formed by centrosymmetric dimers linked by hydrogen bonds, but almost no information is available on this compound concerning proton disorder and the low-temperature phase. However, potassium hydrogencarbonate, KHCO3, which has an isomorphic structure for the high temperature phase, was well studied: it undergoes a non-ferroic, non-ferroelectric phase transition at Tc = 318 K between two monoclinic structures. The protons are disordered in an asymmetric double-well potential in the low-temperature phase, and the double-well potential becomes symmetric in the high-temperature phase. By comparison with recent solid-state NMR experimental results on KHCO3, we show that RbHCO3 undergoes a phase transition at Tc approximately 245 K, and give evidence that the proton dynamic disorder in both compounds is very similar. |
| |
Keywords: | NMR solid‐state NMR 13C cross‐polarization magic angle spinning NMR 87Rb NMR hydrogen bonding phase transition hydrogencarbonates two‐site jump model |
本文献已被 PubMed 等数据库收录! |
|