High Resolution Electron Microscopic Observation of Ferromagnetic Amorphous Ferrites in CaO-Bi2O3-Fe2O3 and Li2O-Bi2O3-Fe2O3 Systems

High resolution electron microscopic (HREM) observation was carried out for the ferromagnetic amorphous ferrites in the CaO-Bi2O3-Fe2O3 and Li2O-Bi2O3-Fe2O3 systems. Although diffuse halo patterns were taken in electron diffraction, the HREM images revealed that microcrystalline domains extending to several nanometers were densely formed in these specimens. The result is consistent with our previous studies by static magnetic measurements and 57Fe Mossbauer spectra analysis. "Magnetic two phase model" that consists of a disordered speromagnetic phase and a microcrystalline ferrimagnetic phase is proposed for the ferromagnetic amorphous ferrites.