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

Abstract

A selective reduction followed by an oxidization roasting process has been reported as an effective route to synthetize spinel manganese ferrite (MnFe2O4). In the current work, during the selective reduction process, the FeyMn1−yO (0 ≤ y ≤ 1) samples that acted as intermediates for synthesizing MnFe2O4 were successfully synthesized from Fe2O3 and Mn2O3 systems. The y-value in the synthetic FeyMn1−yO sample was in the range of 0–1 at 800 °C after 30 min. Next, during the oxidization roasting process, the synthetic MnFe2O4 micro-particles with saturation magnetization of 73.7 emu/g were successfully prepared from the FeyMn1−yO 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 MnFe2O4 samples were systematically investigated by SEM/EDS, XRD, XPS and VSM. Under low temperature (<950 °C), the main reactions were the oxidization of FeyMn1−yO to MnxFe3−xO4 (1 < x ≤ 3), MnxFe3−xO4 (0 < x < 1) and Fe2O3. Under high temperature (>1000 °C), the MnyFe1−yO sample was oxidized to the MnFe2O4 sample, and the normal and inverse spinel structures of MnFe2O4 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 MnFe2O4 micro-particles. Furthermore, this method could be extended to fabricate other spinel ferrite particles of interest.