Synthesis and magnetism property of manganese ferrite MnFe2O4 by selective reduction and oxidization roasting process

A selective reduction followed by an oxidization roasting process has been reported as an effective route to synthetize spinel manganese ferrite (MnFe 2 O 4 ). In the current work, during the selective reduction process, the Fe y Mn 1−y O (0 ≤ y ≤ 1) samples that acted as intermediates for synthesizing MnFe 2 O 4 were successfully synthesized from Fe 2 O 3 and Mn 2 O 3 systems. The y-value in the synthetic Fe y Mn 1−y O sample was in the range of 0–1 at 800 °C after 30 min. Next, during the oxidization roasting process, the synthetic MnFe 2 O 4 micro-particles with saturation magnetization of 73.7 emu/g were successfully prepared from the Fe y Mn 1−y O samples by an oxidization roasting process for 30 min at 1000 °C in air atmosphere. The formation mechanism and interfacial reaction of manganese ferrite spinel MnFe 2 O 4 samples were systematically investigated by SEM/EDS, XRD, XPS and VSM. Under low temperature (<950 °C), the main reactions were the oxidization of Fe y Mn 1−y O to Mn x Fe 3−x O 4 (1 < x ≤ 3), Mn x Fe 3−x O 4 (0 < x < 1) and Fe 2 O 3 . Under high temperature (>1000 °C), the Mn y Fe 1−y O sample was oxidized to the MnFe 2 O 4 sample, and the normal and inverse spinel structures of MnFe 2 O 4 samples inevitably coexisted and were co-transformed at the same time. This study reported a simple synthetic route that combined selective reduction with an oxidization roasting method to successfully synthesize MnFe 2 O 4 micro-particles. Furthermore, this method could be extended to fabricate other spinel ferrite particles of interest.