Characterization and property of magnetic ferrite ceramics with interesting multilayer structure prepared by solid-state reaction

Abstract

Polyhedral MnFe2O4 with multilayer structure was successfully synthesized, and the possible originating mechanism of multilayer structure was firstly determined in current study. The phase formation, morphology evolution and interface reaction of the solid-state reaction of MnO2 and Fe2O3 mixture under air and reduction atmospheres were comparatively investigated, and the microwave absorption property of polyhedral MnFe2O4 with multilayer structure were discussed via the XRD, SEM, XPS, TEM, AFM and vector network analyzer measurements. Experiment results showed that multilayer MnFe2O4 can be synthesized both in the air at 1200–1300 °C and in 4 vol%CO at 1000–1100 °C. The reduction atmosphere was favorable to the formation of multilayer structure of MnFe2O4 due to the occurrence of multilayer MnO as the intermedium. In addition, morphology evolution demonstrated that the particle size of MnO2 after reduction was decreased remarkably which was also beneficial to the formation of MnFe2O4. However, air atmosphere is unfavorable to the generation of MnFe2O4 due to the recrystallization growth of Fe2O3 to lump impeding the element diffusion. Resultantly, the required temperature for the synthesis of MnFe2O4 in air was much higher than that in 4 vol% CO. One possible mechanism for the polyhedral MnFe2O4 with multilayer structure was based on the combination of the greater growth speed of (111) plane in the cubic MnFe2O4 crystal and terrace-ledge-kink (TLK) growth model. Moreover, multilayer MnFe2O4 prepared by the solid-state reaction presented good microwave absorbing property compared with that of the ferrites synthesized via the representative wet chemistry and combined methods.