Sequence of phase transitions in (NH4)3SiF7
DOI:
10.1039/c6dt04874aURI (для ссылок/цитирований):
http://pubs.rsc.org/en/content/articlelanding/2017/dt/c6dt04874a#!divAbstracthttps://elib.sfu-kras.ru/handle/2311/70027
Автор:
Mel'Nikova, S. V.
Molokeev, M. S.
Laptash, N. M.
Pogoreltsev, E. I.
Misyul, S. V.
Flerov, I. N.
Коллективный автор:
Институт инженерной физики и радиоэлектроники
Кафедра теплофизики
Дата:
2017Журнал:
Dalton TransactionsКвартиль журнала в Scopus:
Q1Квартиль журнала в Web of Science:
Q1Библиографическое описание:
Mel'Nikova, S. V. Sequence of phase transitions in (NH4)3SiF7 [Текст] / S. V. Mel'Nikova, M. S. Molokeev, N. M. Laptash, E. I. Pogoreltsev, S. V. Misyul, I. N. Flerov // Dalton Transactions. — 2017. — Т. 46 (№ 8). — С. 2609-2617Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.
Аннотация:
Single crystals of silicon double salt (NH4)(3)SiF7 = (NH4)(2)SiF6 center dot 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) (G(1)) <-> Pbam (Z = 4) (G(2)) <-> P2(1)/c (Z = 4) (G(3)) <-> P (1) over bar (Z = 4) (G(4)) <-> P2(1)/c (Z = 8) (G(5)). 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 center dot center dot center dot F hydrogen bonds can be a driving force of the observed phase transitions.