| Инд. авторы: | Rashchenko S.V., Seryotkin Y.V., Sokol E.V., Kokh S.N. |
| Заглавие: | Incommensurately modulated crystal structure of flamite - Natural analogue of -Ca2SiO4 |
| Библ. ссылка: | Rashchenko S.V., Seryotkin Y.V., Sokol E.V., Kokh S.N. Incommensurately modulated crystal structure of flamite - Natural analogue of -Ca2SiO4 // Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials. - 2019. - Vol.75. - P.1137-1143. - ISSN 2052-5192. |
| Внешние системы: | DOI: 10.1107/S2052520619013623; РИНЦ: 42933656; SCOPUS: 2-s2.0-85076550739; |
| Реферат: | eng: Crystal structures of unquenchable high-temperature polymorphs of Ca2SiO4, important in cement chemistry, have eluded single-crystal X-ray analysis. However, the problem may be addressed by studying chemically stabilized Ca2SiO4 polymorphs at ambient temperature. Here an incommensurately modulated crystal structure of flamite [Pnma(0β0)00s, q = 0.2728 (2)b∗, a = 6.8588 (2) Å, b = 5.4301 (2) Å, c = 9.4052 (3) Å] is described. It is a mineral analogue of orthorhombic -Ca2SiO4 (stable between 1160 and 1425°C), naturally stabilized by substitution with phosphorus. The incommensurate modulation results from wave-like displacement of cation sites accompanied by tilting of (Si,P)O 4 tetrahedra and variation of the Na/(Ca + Na + K) ratio along the modulation period. The studied sample from Hatrurim Basin (Negev Desert, Israel) with composition (Ca 1.75 K 0.12 Na 0.12) 1.99 (Si 0.74 P 0.26) 1.00 O 4 also demonstrates pseudomerohedral cyclic twinning around the a axis, which results from pseudohexagonal topology of the crystal structure and complicates the indexing of X-ray diffraction data. © © International Union of Crystallography 2019.
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| Ключевые слова: | X-ray diffraction data; Single crystal X-ray analysis; Modulated crystals; Incommensurate modulation; High-temperature polymorph; flamite; Calcium orthosilicate; Aperiodic structure; X ray diffraction analysis; Sodium; Crystal structure; Modulation; Energy dispersive X ray analysis; Chemical analysis; Calcium silicate; incommensurate modulation; flamite; combustion metamorphism; calcium orthosilicate; aperiodic structure; Single crystals; |
| Издано: | 2019 |
| Физ. характеристика: | с.1137-1143 |