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Anhydrous Silicophosphoric Acid Glass: Thermal Properties and Proton Conductivity |
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| Authors: | Prof. Takahisa Omata Aman Sharma Prof. Issei Suzuki Tomohiro Ishiyama Shinji Kohara Koji Ohara Prof. Madoka Ono Prof. Yang Ren Khurelbaatar Zagarzusem Prof. Masaya Fujioka Prof. Gaoyang Zhao Prof. Junji Nishii |
| Affiliation: | 1. Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 Japan;2. Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), AIST Central 5, Higashi 1-1-1, Tsukuba, Ibaraki, 305-8565 Japan;3. Research Center for Advanced Measurement and Characterization, National Institute for Materials Science (NIMS), Sengen, Tsukuba, Ibaraki, 305-0047 Japan;4. Diffraction and Scattering Division, Japan Synchrotron Radiation Research Institute (JASRI), Sayo-gun, Hyogo, 679-5198 Japan;5. Research Institute for Electronic Science, Hokkaido University, Kita 21 Nishi 10, Kita-ku, Sapporo, 001-0021 Japan;6. School of Materials Sciences and Technology, Xi'an University of Technology, Xi'an, 710048 P. R. China |
| Abstract: | Anhydrous silicophosphoric acid glass with an approximate composition of H5Si2P9O29 was synthesized and its thermal and proton-conducting properties were characterized. Despite exhibiting a glass transition at 192 °C, the supercooled liquid could be handled as a solid up to 280 °C owing to its high viscosity. The glass and its melt exhibited proton conduction with a proton transport number of ∼1. Although covalent O−H bonds were weakened by relatively strong hydrogen bonding, the proton conductivity (4×10−4 S cm−1 at 276 °C) was considerably lower than that of phosphoric acid. The high viscosity of the melt was due to the tight cross-linking of phosphate ion chains by six-fold-coordinated Si atoms. The low proton conductivity was attributed to the trapping of positively charged proton carriers around anionic SiO6 units (expressed as (SiO6/2)2−) to compensate for the negative charges. |
| Keywords: | fuel cells glasses hydrogen bonds proton transport protonation |