This article is cited in 2 papers

Magnetism

Structural disorder in the paraelectric phase of the Fe$_3$B$_7$O$_{13}$Br boracite

V. A. Shuvaeva^a, K. A. Lyssenko^b, M. Yu. Antipin<sup>b

a</sup> Research Institute of Physics, Southern Federal University
^b A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, Moscow

Abstract: A structural model of the cubic paraelectric phase of a Fe$_3$B$_7$O$_{13}$Br crystal belonging to the boracite family has been developed using the data obtained by single-crystal X-ray diffraction with due regard for the results of extended X-ray absorption fine structure (EXAFS) spectroscopy. It has been shown that the best agreement between the data obtained by these two methods is achieved within a model assuming a disorder in the arrangement of both the Fe and Br atoms and a high degree of correlation of their displacements. It has been found that, during the phase transition from the rhombohedral ferroelectric phase to the cubic paraelectric phase, no significant transformation of the structure is observed on a local level. In this case, a change in the macroscopic symmetry occurs predominantly as a result of the variation in the set of possible spatial orientations of stable structural fragments, which is characteristic of order-disorder phase transitions.

Received: 28.09.2010

 English version: Physics of the Solid State, 2011, 53:4, 730–735

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