Synthesis and cation distribution of copper-substituted spinel-related lithium ferrite

Single-phased Cu2+-substituted spinel-related Li0.5Fe2.5O4 was synthesized by sintering a mixture of Cu2+-substituted corundum-related α-Fe2O3 and Li2CO3 at 700 °C which is ∼325–400 °C lower than the temperature at which the material is prepared by the conventional ceramic methods. X-ray powder diffraction, X-ray photoelectron spectroscopy, Mössbauer spectroscopy and magnetic measurements were used to characterize the material. In contrast to high-temperature synthetic routes, the present one leads to a Cu+-and Fe2+-cation free material, thereby optimizing its technological value. Rietveld refinement of the XRD data favors a structural model in which Cu2+ substitutes for both Fe3+ and Li+ at the octahedral sites. Mössbauer and magnetic data are consistent with this model if spin thermal reversal and/or spin canting are taken into account for the later.