Interplay of inequivalent atomic positions in resonant x-ray diffraction of Fe3BO6

TL;DR

This study investigates the complex resonant x-ray diffraction patterns of Fe3BO6 near the iron K edge, revealing the interplay of inequivalent atomic sites and their impact on diffraction intensities and spectra.

Contribution

It provides a combined theoretical and experimental analysis of forbidden reflections, highlighting the role of site-specific scattering and azimuthal dependencies in Fe3BO6.

Findings

Interference of x-rays from inequivalent Fe sites explains energy spectra.

Azimuthal dependence of reflection intensities is influenced by site-specific resonant scattering.

Effective data correction methods enable high-quality spectra despite experimental challenges.

Abstract

'Forbidden' Bragg reflections of iron orthoborate Fe3BO6 were studied theoretically and experimentally in the vicinity of the iron K edge. Their energy spectra are explained as resulting from the interference of x-rays scattered from two inequivalent crystallographic sites occupied by iron ions. This particular structure property gives rise to complex azimuthal dependences of the reflection intensities in the pre-edge region as they result from the interplay of site specific dipole-quadrupole and quadrupole-quadrupole resonant scattering. Also evidenced is an isotropic character of the absorption spectrum. Self-absorption correction to the diffraction data, as well as possible contributions of thermal vibrations and magnetic order, are discussed. Particular care is given to extracting clean spectra from the data, and it is demonstrated that excellent results can be obtained even from measurements that appear corrupted by several effects such as poor crystal quality and multiple scattering.