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

Vrankić, Martina; Šarić, Ankica; Bosnar, Sanja; Barišić, Dario; Pajić, Damir; Lützenkirchen- Hecht, Dirk; Jelovica Badovinac, Ivana; Petravić, Mladen; Altomare, Angela; Rizzi, Rosanna; Klaser, Teodoro (2021) Structural Behavior and Spin-State Features of BaAl2O4 Scaled through Tuned Co3+ Doping. Inorganic Chemistry, 60 . pp. 8475-8488. ISSN 0020-1669

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Abstract

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

Item Type:	Article
Uncontrolled Keywords:	doped BaAl2O4; X-ray diffraction; Rietveld refinement; X-ray absorption fine structure; zero-field splitting
Subjects:	NATURAL SCIENCES > Chemistry > Inorganic Chemistry
Divisions:	Division of Materials Physics
Depositing User:	Martina Vrankić
Date Deposited:	06 Dec 2022 13:28
URI:	http://fulir.irb.hr/id/eprint/7700
DOI:	10.1021/acs.inorgchem.0c0347

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