Optical and calorimetric studies of K2TaF7
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URI (для ссылок/цитирований):
https://www.sciencedirect.com/science/article/pii/S0022113919300302?via%3Dihubhttps://elib.sfu-kras.ru/handle/2311/129262
Автор:
Mel’Nikova, Svetlana V.
Bogdanov, Evgeniy V.
Molokeev, Maxim S.
Laptash, Natalia M.
Flerov, Igor N.
Коллективный автор:
Институт инженерной физики и радиоэлектроники
Кафедра теплофизики
Базовая кафедра физики твердого тела и нанотехнологий
Дата:
2019Журнал:
Journal of Fluorine ChemistryКвартиль журнала в Scopus:
Q2Квартиль журнала в Web of Science:
Q3Библиографическое описание:
Mel’Nikova, Svetlana V. Optical and calorimetric studies of K2TaF7 [Текст] / Svetlana V. Mel’Nikova, Evgeniy V. Bogdanov, Maxim S. Molokeev, Natalia M. Laptash, Igor N. Flerov // Journal of Fluorine Chemistry. — 2019.Аннотация:
Optical and calorimetric experiments on K2TaF7 are performed in a wide temperature range. No features were
found in the behavior of the birefringence Δnb(T), the angle of rotation of the indicatrix ϕ(T) and the heat
capacity ΔCp(T) except for those associated with the Pnma↔P21/c phase transition. Structural transformation
was characterized as strong first order “proper” ferroelastic accompanied by a huge angle ϕ ≈40° and strong pretransition
phenomena in Δnb(T). Two contributions to the anomalies of the optical properties were found associated
with the photoelastic effect and the transition parameter related linearly to the spontaneous deformation.
Thermal treatments cause correlated changes in temperature and enthalpy of the phase transition,
which leads to the invariance of the large magnitude of the corresponding entropy ΔS=22 J/mol·K which does
not match the model with the absence of structural disorder in the Pnma phase.