Crystal and local atomic structure of Co-doped MgFeBO_4 warwickites

TL;DR

This study investigates how Co doping affects the crystal and local atomic structure of MgFeBO_4 warwickites using advanced spectroscopic techniques across a wide temperature range.

Contribution

It provides new insights into the local structural distortions and M-O bond anisotropy caused by Mg substitution with Co in MgFeBO_4 warwickites.

Findings

Co doping influences local structural distortions.

Mg substitution by Co causes M-O bond anisotropy.

Charge states and local environments of Fe and Co are characterized.

Abstract

Single crystalline MgFeBO_4, Mg_0.5Co_0.5FeBO_4 and CoFeBO_4 have been grown by the flux method. The samples have been characterized by X-ray spectral analysis, X-ray diffraction and X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra have been measured at the Fe andCoK-edges over a wide temperature range (6.5 - 300 K). The composition, the charge state and local environment of both Fe and Co atoms have been determined. The effects of Mg substitution by Co on the local structural distortions have been revealed experimentally and the M-O bond anisotropy has been found.