Тип публикации: статья из журнала
Год издания: 2017
Идентификатор DOI: 10.1039/c6dt04874a
Ключевые слова: Group theory, Single crystals, X ray diffraction, Atomic displacement, Double salts, Driving forces, Group-theoretical analysis, Order parameter, Polarization optics, Temperature changes, Hydrogen bonds
Аннотация: Single crystals of silicon double salt (NH4)3SiF7 = (NH4)2SiF6·NH4F = (NH4)3[SiF6]F were grown and studied by the methods of polarization optics, X-ray diffraction and calorimetry. A sequence of symmetry transformations with the temperature change was established: P4/mbm (Z = 2) (G1) - Pbam (Z = 4) (G2) - P21/c (Z = 4) (G3) - P1 (ZПоказать полностью= 4) (G4) - P21/c (Z = 8) (G5). Crystal structures of different phases were determined. The experimental data were also interpreted by a group-theoretical analysis of the complete condensate of order parameters taking into account critical and noncritical atomic displacements. Strengthening of the N-H?F hydrogen bonds can be a driving force of the observed phase transitions. © The Royal Society of Chemistry.
Журнал: Dalton Transactions
Выпуск журнала: Vol. 46, Is. 8
Номера страниц: 2609-2617