Temperature Dependent EXAFS Study of the Local Structure of Fe 3 B 7 O 13 Br

The local structure around Br ion has been studied by Br K-edge XAFS in rhombohedral, orthorhombic and cubic phases of Fe 3 B 7 O 13 Br at temperatures from 300 to 660 K. It has been shown, that in the rhombohedral and orthorhombic phases Br-Fe distances were in a good agreement with X-ray diffraction data, however in the cubic phase the local environment of Br couldn't be described by the ideal cubic model. Br-Fe atomic distribution in the cubic phase appeared to be similar to that in the low-temperature ferroelectric phases. This shows that the cubic phase is essentially disordered.

Keywords:

• Xafs
• Boracite
• Local Structure
• Ferroelectrics