Proton dynamics in Cs3(HSO4)2(HPO4) studied by 1H NMR |
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| Affiliation: | 1. Division of Forest and Biomaterials Science, Kyoto University, Kyoto 606-8502, Japan;2. National Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan;1. Department of Chemistry, University of Munich (LMU), Butenandtstr. 5–13, 81377, Munich, Germany;2. Mineralogical State Collection Munich (SNSB), Theresienstr. 4, 80333, Munich, Germany;1. School of Molecular Bioscience, University of Sydney, NSW 2006, Australia;2. Department of Chemistry, University of Southampton, Highfield, SO17 1BJ, UK;1. College of Basic Medical Science, Guiyang Medical University, Guiyang, Guizhou 550004, China;2. College of Pharmacy, Guiyang Medical University, Guiyang, Guizhou 550004, China;3. Engineering Research Center for the Development and Application of Ethnic Medicine and TCM, Ministry of Education, Guiyang Medical University, Guiyang, Guizhou 550004, China;1. Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Model Physics, Northwest University, Xi’an 710069, China;2. Multidisciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China;1. CSIRO Mineral Resources, Lucas Heights, NSW 2234, Australia;2. CSIRO Manufacturing, Clayton, Victoria 3168, Australia |
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| Abstract: | Proton dynamics in Cs3(HSO4)2(H2PO4) has been studied by means of 1H solid-state NMR as well as thermal analyses. The thermal analysis shows an endothermic peak at 408 K, which corresponds to a superprotonic transition. Above the transition temperature a mass loss is observed in a dry atmosphere, which is easily recovered in a conventional dry atmosphere below the transition temperature. The 1H magic-angle-spinning NMR spectra at room temperature show two peaks at 13.5 and 15.8 ppm, and a shoulder at 11.3 ppm from tetramethylsilane, demonstrating a presence of several inequivalent proton sites. Translational diffusion of protons takes place in both a room-temperature phase (RT) and a high-temperature phase (HT). In both phases reorientation of the SO4/PO4 tetrahedron limits the rate of the proton transport. The 1H mean residence times are estimated as Ea = 33 kJ mol− 1 and τ0 = 0.97 × 10− 9 s for phase RT from the second moment analysis and as Ea = 20 kJ mol− 1 and τ0 = 5.0 × 10− 12 s for phase HT from the analysis of the 1H T1 results. |
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