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

Single-phased Cu²⁺-substituted spinel-related Li_0.5Fe_2.5O₄ 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.