ON THE P6(3) MMC TO P6(3)CM PHASE-TRANSITION - APPLICATION TO KNICL3 AND RBFEBR3/

Citation
Zw. Hendrikse et Wja. Maaskant, ON THE P6(3) MMC TO P6(3)CM PHASE-TRANSITION - APPLICATION TO KNICL3 AND RBFEBR3/, Physica. B, Condensed matter, 233(2-3), 1997, pp. 139-152
Citations number
21
Categorie Soggetti
Physics, Condensed Matter
ISSN journal
09214526
Volume
233
Issue
2-3
Year of publication
1997
Pages
139 - 152
Database
ISI
SICI code
0921-4526(1997)233:2-3<139:OTPMTP>2.0.ZU;2-W
Abstract
In this paper a model is presented, describing the phase transition of a high-symmetry phase, the hexagonal perovskite (2L) structure, space group P6(3)/mmc, to a low-symmetric phase, P6(3)cm. The model is base d on the hypothesis that the ion size radius ratio of K and Cl (RA+ an d RX-) determines the structural (and dynamical) behaviour of the ABX( 3) hexagonal perovskites. The consequences for a global displacement p attern, resulting from a collapse of the local A cation environment ar e carried through. Among others, the low-symmetry phase P6(3)cm is fou nd. Although the phase transition occurs at K = (2 pi/3a,2 pi/3a, 0), various other points of high symmetry have been subject of considerati on in our analysis. Applications to KNiCl3, RbFeBr3 and TlFeBr3 are pu t forward and discussed.