Electrophysical and Optical Properties of Cobalt Ferrite Alloys with Different Stoichiometric Compositions Produced in the Large Solar Furnace
Abstract
The electrophysical and optical properties of cobalt ferrite (CoFe2O4) alloys with different stoichiometric compositions synthesized using the Large Solar Furnace (LSF) were studied. The samples were produced from mixtures of cobalt oxide (CoO) and iron oxide (Fe2O3) in various ratios, followed by rapid cooling at a rate of 1000°C/s. The resistivity was measured by the van der Pauw method, and the optical properties were analyzed using UV–Vis spectrophotometry. The results showed that the maximum resistivity (7.8 × 107 Ω cm) is observed for the stoichiometric composition CoFe2O4 (33.3% CoO + 66.7% Fe2O3), which is associated with a high degree of crystallinity and the predominance of the spinel phase. Optical studies revealed a dependence of the absorption spectra on the phase composition, with peaks in the ultraviolet range (290 nm) for samples with a high purity of the ferrite phase. The band gap for CoFe2O4 was 3.90 eV, exceeding reference values due to quantum-size effects and the presence of interphase boundaries. These results demonstrate the influence of stoichiometry and synthesis conditions on the functional properties of cobalt ferrites.