Antimony dispersion and phase evolution in the Sb2O3-Fe2O3 system.
1College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China. huangy@njut.edu.cn
Antimony spreading in Fe2O3-Sb2O3 systems is influenced by temperature and oxidation. Mechanical grinding enhances antimony trioxide dispersion, impacting surface segregation during heating and solid-state reactions.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Surface Science
Background:
- Understanding antimony (Sb) behavior in iron oxide (Fe2O3) systems is crucial for materials processing.
- Oxidation and solid-state reactions significantly influence element distribution and phase formation.
Purpose of the Study:
- To investigate the spreading and segregation of antimony during oxidation and solid-state reactions in the Fe2O3-Sb2O3 system.
- To characterize the new phases formed and understand their impact on antimony surface segregation.
Main Methods:
- Characterization techniques including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Differential Scanning Calorimetry (TG-DSC).
- X-ray Photoelectron Spectroscopy (XPS) was critically used to measure surface atomic ratios.
- Mechanical grinding was employed to assess the influence of particle dispersion on reactivity.
Main Results:
- Sb2O4 and FeSbO4 were identified as the sole new phases.
- Mechanical grinding of Sb2O3 and Fe2O3 enhanced Sb2O3 dispersion, unlike Sb2O4.
- Surface Sb/Fe ratio (R(Sb/Fe)) peaked around 400°C due to Sb2O3 oxidation to Sb2O4, then decreased with further heating and FeSbO4 formation, yet remained elevated.
Conclusions:
- Antimony trioxide (Sb2O3) dispersion and subsequent oxidation to antimony tetroxide (Sb2O4) significantly affect surface segregation in Fe2O3-Sb2O3 mixtures.
- The formation of iron antimonate (FeSbO4) at higher temperatures further modifies the surface Sb/Fe ratio.
- Even after complete transformation to FeSbO4, the surface Sb/Fe ratio remained substantially higher than the bulk ratio.
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