Тип публикации: статья из журнала
Год издания: 2010
Идентификатор DOI: 10.1134/S1063783410100240
Аннотация: Polarization-optical studies and measurements of the birefringence ?n and the angle of rotation of the optical indicatrix for the (NH4)2NbOF5 crystal have been carried out in the temperature range 100-350 K. Two anomalies of the birefringence have been revealed at the temperatures T01 = 258 K and T02 ? 219 K. According to the twinnПоказать полностьюing pattern, the crystal undergoes successive changes in symmetry: orthorhombic - monoclinic 1 - monoclinic 2. The twofold axis of the monoclinic phases (or the normal to the plane) is directed along [001]or. The effect of the uniaxial compression along [011]or and the electric field E ? 25 kV/cm along [100]or on the twin structure has been studied. The ferroelastic phase transition at T01 is due to the appearance of the shear deformation x4(T) and is accompanied by significant anomalies of the birefringence. Strong pretransition phenomena mask the jumps in the birefringence ?n(T) and in the angle of rotation of the indicatrix ?(T) at T01. © 2010 Pleiades Publishing, Ltd.
Журнал: Physics of the Solid State
Выпуск журнала: Т. 52, № 10
Номера страниц: 2168-2172
ISSN журнала: 10637834
Место издания: Санкт-Петербург
Издатель: Pleiades Publishing, Ltd. (Плеадес Паблишинг, Лтд)