Abstract
Molten ferrite systems are used in the smelting and refining processes in steelmaking, to reduce the loss of metals in slags and to accelerate reaction rates. Here, high-energy x-ray diffraction experiments have been performed on aerodynamically levitated molten spheres of 43BaO-57FeOX and 43SrO-57FeOX at 1873 K using laser beam heating. The composition was varied within the range of x = 1-1.5 by changing the oxygen partial pressure of the levitation gas. The corresponding x-ray pair distribution functions have been interpreted using empirical potential structure refinement (EPSR) modeling. In oxygen-rich melts (x = 1.5), our EPSR models indicate very similar structures for the different alkaline-earth liquids, with both the Ba-O and Sr-O coordination numbers to be ∼8.4 and the total Fe-O coordination numbers ∼5.7. However, our models show that in reducing environments, the Fe3+ and Fe2+ ions exhibit very different behaviors in the Ba- and Sr-ferrite liquids. In the Ba-ferrite melt, the Fe3+-O coordination number decreases from 5.7 (at x = 1.5) to 5.2 (at x = 1.07), whereas Fe2+-O remains constant at ∼5.0 across the same compositional range. In the Sr melts, both the Fe2+-O and Fe3+-O coordination numbers rise from ∼5.7 (at x = 1.5) to 6.3 (at x = 1.07). All models show the structures to be heterogeneous with intertwined nanometer sized clusters or channels of Ba/Sr-O and Fe-O polyhedra that grow as oxygen content is reduced. Changes in the viscosity and electrical properties are interpreted in terms of the number of bridging and non-bridging oxygens associated with FeO4 tetrahedra and concentration of charge carriers, respectively.
Recommended Citation
C. J. Benmore et al., "Structure-property Relations of Binary Ferrite Melts," Journal of Applied Physics, vol. 137, no. 8, article no. 085903, American Institute of Physics, Feb 2025.
The definitive version is available at https://doi.org/10.1063/5.0242452
Department(s)
Materials Science and Engineering
International Standard Serial Number (ISSN)
1089-7550; 0021-8979
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2025 American Institute of Physics, All rights reserved.
Publication Date
28 Feb 2025
Comments
Basic Energy Sciences, Grant 201706890053