Abstract:
Powders of calcium-substituted hematite were synthesized via hydrothermal method. The samples were char
acterized using X-ray diffraction, Mossbauer ¨ spectroscopy, scanning electron microscopy, energy-dispersive Xray spectroscopy, Fourier-transform infrared spectroscopy, and magnetometry. Structural analysis revealed that
Ca-substituted samples maintained single-phase hematite for Fe/Ca ratios between 11 and 5. Further increase in
calcium concentration led to formation of a defective iron-calcium spinel phase. Infrared spectra confirmed the
presence of hydroxyl groups within the hematite lattice. The incorporation of calcium and associated defects
significantly influenced the magnetic properties of hematite, inducing ferromagnetic behavior. The maximum
magnetization value of 12.9 emu/g was achieved at Fe/Ca = 6, representing a substantial enhancement
compared to most other doped hematites. These materials show potential for applications in hyperthermia, MRI
contrast enhancement, and wastewater treatment.
