Phase Diagram for the NaBH4-KBH4 System and the Stability of a Na1-xKxBH4 Solid Solution
| Autor: | Lars H. Jepsen, Torben R. Jensen, Steffen R. H. Jensen, Jørgen Skibsted |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Coordination sphere
Chemistry Analytical chemistry SUBSTITUTION FRAMEWORKS THERMAL-DECOMPOSITION NMR Surfaces Coatings and Films Electronic Optical and Magnetic Materials Ion Metal General Energy visual_art METAL BOROHYDRIDES visual_art.visual_art_medium ABSORPTION Binary system Physical and Theoretical Chemistry Solubility Thermal analysis COMPLEX HYDRIDES HYDROGEN STORAGE MATERIALS Phase diagram Solid solution |
| Zdroj: | Jensen, S R H, Jepsen, L H, Skibsted, J & Jensen, T R 2015, ' Phase Diagram for the NaBH 4-KBH 4 System and the Stability of a Na 1-x K x BH 4 Solid Solution ', The Journal of Physical Chemistry Part C, vol. 119, no. 50, pp. 27919-27929 . https://doi.org/10.1021/acs.jpcc.5b09851 |
| DOI: | 10.1021/acs.jpcc.5b09851 |
| Popis: | The binary system NaBH4–KBH4 has been systematically investigated by several complementary techniques, including in situ synchrotron radiation powder X-ray diffraction (SR-PXD), thermal analysis, and in situ 11B and 23Na magic-angle spinning (MAS) NMR. Full solubility in the system NaBH4–KBH4 and formation of a solid solution, Na1–xKxBH4, 0 110 °C, are observed. The Na1–xKxBH4 solid solution is most clearly observed by 11B MAS NMR, which reveals a binomial distribution of Na+ and K+ ions over the six metal sites in the first coordination sphere of the BH4– unit, i.e., seven almost equally distinct peaks in the range −36.4 to −42.6 ppm with a systematic change of 1.0 ± 0.1 ppm toward lower frequency for each replacement of K+ by Na+. The solid solution Na1–xKxBH4 is metastable at room temperature, and 75% of Na0.5K0.5BH4 has separated into NaBH4 and KBH4 after 24 h at ∼24 °C, as observed by in situ 23Na and 11B MAS NMR. The composition 0.682NaBH4–0.318KBH4 has the lowest m... |
| Databáze: | OpenAIRE |
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