Тип публикации: статья из журнала
Год издания: 2012
Идентификатор DOI: 10.1134/S1063783412010234
Аннотация: The structures of two phases of the (NH4)(3)Nb(O-2)(2)F-4 crystal, namely, the parent cubic phase and the most distorted low-temperature phase, have been determined from data of an X-ray diffraction experiment performed for a powder sample. The profile and structural parameters have been refined according to the procedure implementПоказать полностьюed in the DDM program. The results obtained have been discussed with invoking the group-theoretical analysis of the complete order parameter condensate, which takes into account the critical and noncritical atomic displacements and allows the interpretation of the obtained experimental data. It has been found that the most probable sequence of structural transformations occurring in the crystal can be schematically represented in the following form: F3 (3) over barm Gamma(+)(5)(11-7)/(eta 1,eta 1,eta) C2/m Gamma(+)(5)(11-7) circle times Sigma(2)(4-2)/(eta 1,eta 1,eta)(0,0,0,0,0,xi,0,-xi,0,0,0,0) P2(1)/m Gamma(+)(5)(11-7) circle times Sigma(2)(4-2) circle times Sigma(3)(4-3)/ (eta 1,eta 1,eta)(0,0,0,0,0,xi,0,-xi,0,0,0,0)(0,0,0,0,0,epsilon,0,epsilon,0,0,0) P2(1)/n
Журнал: PHYSICS OF THE SOLID STATE
Выпуск журнала: Vol. 54, Is. 1
Номера страниц: 143-154
ISSN журнала: 10637834
Место издания: NEW YORK
Издатель: MAIK NAUKA/INTERPERIODICA/SPRINGER