Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
Incommensurately modulated crystal structure of flamite - Natural analogue of -Ca2SiO4. / Rashchenko, Sergey V.; Seryotkin, Yurii V.; Sokol, Ella V. и др.
в: Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials, Том 75, 12.2019, стр. 1137-1143.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
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TY - JOUR
T1 - Incommensurately modulated crystal structure of flamite - Natural analogue of -Ca2SiO4
AU - Rashchenko, Sergey V.
AU - Seryotkin, Yurii V.
AU - Sokol, Ella V.
AU - Kokh, Svetlana N.
PY - 2019/12
Y1 - 2019/12
N2 - 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.
AB - 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.
KW - aperiodic structure
KW - calcium orthosilicate
KW - combustion metamorphism
KW - flamite
KW - incommensurate modulation
KW - PHASE
KW - SOLID-SOLUTION
KW - NA
KW - TEMPERATURE
KW - ROCKS
KW - DICALCIUM
UR - http://www.scopus.com/inward/record.url?scp=85076550739&partnerID=8YFLogxK
U2 - 10.1107/S2052520619013623
DO - 10.1107/S2052520619013623
M3 - Article
C2 - 32830693
AN - SCOPUS:85076550739
VL - 75
SP - 1137
EP - 1143
JO - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
JF - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
SN - 2052-5192
ER -
ID: 22997673