Effect of Fe-substitution on the structure and magnetism of single crystals Mn2-xFexBO4

Publication date: 1 October 2017
Source:Journal of Crystal Growth, Volume 475
Author(s): M.S. Platunov, N.V. Kazak, Yu.V. Knyazev, L.N. Bezmaternykh, E.M. Moshkina, A.L. Trigub, A.A. Veligzhanin, Y.V. Zubavichus, L.A. Solovyov, D.A. Velikanov, S.G. Ovchinnikov
Single crystalline Mn2-xFexBO4 with x =0.3, 0.5, 0.7 grown by the flux method have been studied by means of X-ray diffraction and X-ray absorption spectroscopy at both Mn and Fe K edges. The compounds were found to crystallize in an orthorhombic warwickite structure (sp. gr. Pnam ). The lattice parameters change linearly with x thus obeying the Vegard’s law. The Fe³⁺ substitution for Mn³⁺ has been deduced from the X-ray absorption near-edge structure (XANES) spectra. Two energy positions of the absorption edges have been observed in Mn K-edge XANES spectra indicating the presence of manganese in two different oxidation states. Extended X-ray absorption fine structure (EXAFS) analysis has shown the reduction of local structural distortions upon Fe substitution. The magnetization data have revealed a spin-glass transition at T SG =11, 14 and 18K for x =0.3, 0.5 and 0.7, respectively.