Magnetic and Magnetization Properties of Co-Doped Fe₂O₃ Thin Films

Effect of Co Doping on Magnetic and CO-SCR Properties of γ-Fe2O3

“…The saturation magnetization ( M s ) value of γ-Fe 2 O 3 is around 60 emu/g, smaller than that of massive γ-Fe 2 O 3 (i.e., 73.5 emu/g), which is caused by surface spin canting effect. − It also indicates that the magnetic properties of Fe 3 O 4 intermediates do not weaken remarkably after the calcination treatment, so γ-Fe 2 O 3 maintains the magnetic properties near to the Fe 3 O 4 intermediate products . However, according to previous reports, with an increase in the Co doping amount, the magnetic properties of the samples should show a changing trend of increasing first and decreasing afterward. , So, 5Co–Fe with the best catalytic activity may have the strongest magnetic properties.…”

“…Akbar reported the synthesis and characterization of Co-doped Fe 2 O 3 thin films with the ratio Co/Fe between 0 and 10%. Magnetic hysteresis loops at room-temperature magnetism showed that with an increase of doping concentration, the saturation magnetization increased with the maximum value at 8%, but when the doping concentration increased to 10%, the magnetization decreased, which might be the result of more Co atoms that were dispersed at the grain boundaries . Our group’s research shows that magnetism can promote the adsorption and transformation of NO molecules on magnetic substances.…”

“…However, after careful observation and comparison, it was found that with an increase of Co doping, sizes of bayberry-like microspheres decreased first and then increased, and the particle size of 5Co–Fe is relatively small and uniform. To further ascertain the morphological change of γ-CoFe 2 O 3 catalysts, the particle size of smaller iron oxide granules on these bayberry-like microspheres can be calculated according to the sample XRD patterns and the following Debye–Scherrer equation where D is the average crystallite size, λ is the wavelength of the incident X-ray beam (1.540 Å), θ is the Bragg diffraction angle, and β is the peak width at half-maximum (FWHM). According to the detailed results presented in Table , the average crystallite sizes of γ-CoFe 2 O 3 samples are in the range 11–13 nm …”

“…Magnetic hysteresis loops at room-temperature magnetism showed that with an increase of doping concentration, the saturation magnetization increased with the maximum value at 8%, but when the doping concentration increased to 10%, the magnetization decreased, which might be the result of more Co atoms that were dispersed at the grain boundaries. 31 Our group's research shows that magnetism can promote the adsorption and transformation of NO molecules on magnetic substances. The magnetism of γ-Fe 2 O 3 increases slightly after use in a reducing atmosphere because when γ-Fe 2 O 3 transcrystallizes to Fe 3 O 4 it will exhibit better stability, magnetism, and catalytic properties.…”

“…Whether Fe 3 O 4 or Fe­(III)­[Fe­(II)­Fe­(III)]­O 4 , its trans-spinel structure, morphology, and crystal form remain basically unchanged when it gradually weathered and oxidized to γ-Fe 2 O 3 . As a result, γ-Fe 2 O 3 obtained after oxidation maintains the trans-spinel structure. ,, After Fe 3 O 4 oxidized to γ-Fe 2 O 3 , one-third of Fe 2+ move to the surface and oxidized, causing five-sixths of these octahedral positions in its cell to be occupied by Fe 3+ and the rest about one-sixth are cation vacancies on octahedrons (shown in Figure ). Because of the defects of the structure, it has a greater potential use value.…”