Highly Symmetric AB2 Framework Related to Tridymite in the Disordered Nitridosilicate La24Sr14–7x[Si36N72](O1–xFx)14 (x = 0.489)
| Autor: | Wolfgang Schnick, Gavin Vaughan, Felix Fahrnbauer, Dajana Durach, Oliver Oeckler, Lukas Neudert |
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| Rok vydání: | 2017 |
| Předmět: |
Diffraction
Chemistry Oxide 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Synchrotron 0104 chemical sciences law.invention Inorganic Chemistry Crystallography chemistry.chemical_compound Tridymite Microcrystalline Electron diffraction law Transmission electron microscopy Physical and Theoretical Chemistry 0210 nano-technology Spectroscopy |
| Zdroj: | Inorganic Chemistry. 56:13070-13077 |
| ISSN: | 1520-510X 0020-1669 |
| Popis: | La24Sr14–7x[Si36N72](O1–xFx)14 with x = 0.489 was obtained as a microcrystalline product by metathesis at 1500 °C in a radio-frequency furnace starting from Si(NH)2, La(NH2)3, SrH2, LaF3, and CeF3. The structure of the new nitridosilicate oxide fluoride was determined by combining transmission electron microscopy (TEM) and single-crystal X-ray diffraction using a microfocused synchrotron beam. The structure model with pronounced disorder [P63/mmc, Z = 1, a = 16.2065(3), c = 9.4165(1) A, R1(obs) = 0.0436] was confirmed by electron diffraction and aberration-corrected Z-contrast scanning TEM. The highly symmetric AB2 framework, which was theoretically predicted but not yet realized, consists of all-side vertex-sharing SiN4 tetrahedra that form channels along [001] filled with La, Sr, O, and F atoms. The connectivity pattern is related to that of tridymite. X-ray spectroscopy and bond-valence-sum calculations were further taken into account for assignment of the N, O, and F atoms. |
| Databáze: | OpenAIRE |
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