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A non-typical sequence of phase transitions in (NH4)3GeF7: optical and structural characterization
Автор | Mel’Nikova, S. V. | |
Автор | Molokeev, M. S. | |
Автор | Laptash, N. M. | |
Автор | Misyul, S. V. | |
Дата внесения | 2016-11-11T08:51:11Z | |
Дата, когда ресурс стал доступен | 2016-11-11T08:51:11Z | |
Дата публикации | 2016 | |
Библиографическое описание | Mel’Nikova, S. V. A non-typical sequence of phase transitions in (NH4)3GeF7: optical and structural characterization [Текст] / S. V. Mel’Nikova, M. S. Molokeev, N. M. Laptash, S. V. Misyul // Dalton Transactions. — 2016. — Т. 45 (№ 12). — С. 5321-5327 | |
ISSN | 14779226 | |
URI (для ссылок/цитирований) | https://elib.sfu-kras.ru/handle/2311/27912 | |
Аннотация | Single crystals of germanium double salt (NH4)3GeF7 = (NH4)2GeF6·NH4F = (NH4)3[GeF6]F were grown and studied by the methods of polarization optics and X-ray diffraction. The birefringence Δn= (no - ne), the rotation angle of the optical indicatrix (T) and unit cell parameters were measured in the temperature range100-400 K. Three structural phase transitions were found at the temperatures: T1↓ = 279.2 K (T1↑ = 279.4 K), T2↑ = 270 K (T2↓ = 268.9 K), T3↓ = 218 K (T3↑ = 227 K). An unusual sequence of symmetry transformations with temperature change was established: P4/mbm (Z = 2) (G1) 虠 Pbam (Z = 4) (G2) 虠 P21/c Single crystals of germanium double salt (NH4)3GeF7 = (NH4)2GeF6·NH4F = (NH4)3[GeF6]F were grown and studied by the methods of polarization optics and X-ray diffraction. The birefringence Δn = (no − ne), the rotation angle of the optical indicatrix ϕ(T) and unit cell parameters were measured in the temperature range 100–400 K. Three structural phase transitions were found at the temperatures: T1↓ = 279.2 K (T1↑ = 279.4 K), T2↑ = 270 K (T2↓ = 268.9 K), T3↓ = 218 K (T3↑ = 227 K). An unusual sequence of symmetry transformations with temperature change was established: P4/mbm (Z = 2) (G1) ↔ Pbam (Z = 4) (G2) ↔ P21/c (Z = 4) (G3) ↔ Pa[3 with combining macron] (Z = 8) (G4). The crystal structures of different phases were determined. The experimental data were additionally interpreted by a group-theoretical analysis of the complete condensate of order parameters taking into account the critical and noncritical atomic displacements. Strengthening of the N–H⋯F hydrogen bonds can be a driving force of the observed phase transitions. | |
Ссылка на другой сайт | http://pubs.rsc.org/en/Content/ArticleLanding/2016/DT/C5DT04907E#!divAbstract | |
Название | A non-typical sequence of phase transitions in (NH4)3GeF7: optical and structural characterization | |
Тип | Journal Article | |
Тип | Published Journal Article | |
Страницы | 5321-5327 | |
ГРНТИ | 29.19.04 | |
Дата обновления | 2016-11-11T08:51:10Z | |
DOI | 10.1039/C5DT04907E | |
Институт | Институт инженерной физики и радиоэлектроники | |
Подразделение | Базовая кафедра физики твердого тела и нанотехнологий | |
Журнал | Dalton Transactions | |
Квартиль журнала в Scopus | Q1 | |
Квартиль журнала в Web of Science | Q1 |