| Autor: |
Davydov, A. V., Vinogradova, Yu. G., Sagatov, N., Bekker, T. B. |
| Předmět: |
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| Zdroj: |
Journal of Structural Chemistry; May2023, Vol. 64 Issue 5, p932-941, 10p |
| Abstrakt: |
Ba4B11O20F crystals are grown from the compositions of the BaF2–B2O3–Na2O–K2O system. It is established that Ba4B11O20F decomposes under 3 GPa and 6 GPa into the β-BaB4O7 barium tetraborate (Pnam) and the end-member of the Ba7(BO3)4–xF2+3x solid solution (P63). The latter has the Ba7(BO3)3F5 composition (x = 1) and does not exist under atmospheric pressure. Raman spectra of the Ba7(BO3)4–xF2+3x phase are studied for the first time. The fact that Raman spectra of the members of the solid solution synthesized under atmospheric pressure are identical to those synthesized under 3 GPa and 6 GPa indicates that the Ba7(BO3)4–xF2+3x (P63) polymorph is stable under these pressures. It is established that pressures of 3 GPa and 6 GPa enhance the incorporation of fluorine into the structure of the Ba7(BO3)4–xF2+3x solid solution and allow replacing all isomorphic anionic groups by [F4]4– groups. It is shown by numerical methods that the solid-phase decomposition of Ba4B11O20F into β-BaB4O7 and Ba7(BO3)3F5 phases occurs at 0 K under 1.3 GPa. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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