Structural Behavior and Spin-State Features of BaAl2O4 Scaled through Tuned Co3+ Doping

Pure and Co3+-doped BaAl2O4 [Ba(Al1-xCox)2O4, x = 0, 0.0077, 0.0379] powder samples were prepared by a facile hydrothermal route. Elemental analyses static secondary ion mass spectrometry (SIMS), X-ray absorption spectroscopy (XAS) measurements at the Co K-edge, diffraction studies fully correlated, thus addressing complete description of structural complexity powder. Powder (PXRD) patterns indicated that nanocrystalline with hexagonal P63 symmetry. The near-edge structure (XANES) revealed presence cobalt in +3 oxidation state, while rarely documented, tetrahedral symmetry around Co3+ was extracted from extended fine (EXAFS) oscillation patterns. Rietveld refinements showed preferentially substitutes Al3+ Al3 sites host lattice, whereas (Al3)O4 tetrahedra remain rather regular Co3+-O distances ranging 1.73(9) to 1.74(9) A. underlying magneto-structural features unraveled through axial rhombic zero-field splitting (ZFS) terms. increased substitution leads an increase ZFS terms 10.8 26.3 K, parameters across series change range 2.7 10.4 showing considerable anisotropy together values anisotropic g-tensor components flowing 1.7 2.5. We defined line between doping limit influenced characteristics, enabling design strategy control terms' contributions magnetic within