Ferritization of copper ions in the Cu–Fe–O system

Abstract

Ferrite ceramics were prepared utilizing solid state reactions between CuO and Fe 3O 4 or α-Fe 2O 3. The samples were analyzed with X-ray diffraction, 57Fe Mössbauer and FT-IR spectroscopies. For the solid state reaction between CuO and Fe 3O 4, the initial atomic ratios of Cu:Fe varied between 1:299 and 1:2. With an increase in the amount of CuO in the initial reaction mixture, there was a corresponding increase in cuprospinel (cubic CuFe 2O 4) in the final products of the synthesis. For the initial molar ratio of Cu:Fe=1:2, cuprospinel phase (0.85) and CuFeO 2 phase (0.15) were found by XRD, as the result of solid state reaction between CuO and Fe 3O 4. In this sample, a small amount of CuO was also detected. For the solid state reaction between CuO and α-Fe 2O 3, the initial molar ratio of 1:1 was used. The samples prepared at a maximum temperature of 800°C, contained similar fractions of tetragonal and cubic CuFe 2O 4 phases, and also minor phases of CuO and α-Fe 2O 3 as found by XRD. In the samples prepared at between 1000 and 1350°C, the cubic CuFe 2O 4 phase was found together with small amounts of CuFeO 2 and CuO. Mössbauer spectra showed hyperfine field distributions and on the basis of these spectra, calculated parameters, the possible presence of Cu + and Fe 2+ ions in the samples was discussed. For the samples prepared at 1350°C the FT-IR spectrum suggested a significant increase in Fe 2+ ions, whereas the Mössbauer spectrum and calculated parameters were similar to those for the compound Cu 0.7Fe 2.3O 4.