Journal of Siberian Federal University. Mathematics & Physics / Structural Changes during Phase Transitions, Critical and Noncritical Order Parameters in the Elpasolite Cs2RbDyF6

Full text (.pdf)
Issue
Journal of Siberian Federal University. Mathematics & Physics: 2012, Vol. 5, Issue 4
Authors
Misjul, Sergey V.; Molokeev, Maksim S.; Osokina, Liliya V.; Saphonov, Ivan N.
Contact information
Misjul, Sergey V. : e-mail: ; Molokeev, Maksim S. : e-mail: ; Osokina, Liliya V. : e-mail: ; Saphonov, Ivan N. : e-mail:
Keywords
elpasolite; X-ray experiment; structural data; a complete condensate of order parameters; irreducible representations; critical distortion; phase transition
Abstract

According to X-ray experiment on the powder sample determined the structure of the initial cubic and the low-temperature monoclinic phases of the crystal Cs2RbDyF6. The refinement of the profile and structural parameters has been carried out by the technique implemented in the DDM program, which minimizes the differences between the derivatives of the calculated and measured X-rays intensities over the entire profile of the X-ray diffraction pattern. The results obtained have been discussed using the group-theoretical analysis of the complete order parameters condensate, which takes into account the critical and noncritical atomic displacements and permits the interpretation of the experimental data obtained previously. It has been reliable established that the sequence of changes in the symmetry during phase transitions in Cs2RbDyF6 can be represented as Fm¯3m 11−9(+ 4 ) −−−−−−−! (',0,0) I4/m 11−9(+ 4 ) −−−−−−−! (',',0) I2/m 11−9(+ 4 )10−3(X+ 3 ) −−−−−−−−−−−−−−! (',', ) P21/n.

Pages
566-575
Paper at repository of SibFU
http://elib.sfu-kras.ru/handle/2311/3113