Microstructures and High Frequency Properties of Sm3+ Doped Co2Z-Type Hexagonal Ferrites as Anti-EMI Magnetic Bead Materials

The Sm3+ doped Co(2)Z-type hexagonal ferrite materials were prepared by conventional ceramic method and characterized by techniques such as X-ray diffractometer and scanning electron microscopy. The influence of a small amount of Sm3+ addition on structures and magnetic properties of the materials was investigated. The results show that Co(2)Z-type hexaferrite is still in the main phase of the Co(2)Z ferrite materials doped with Sm3+. It is observed that Sm-rich phase with granular morphology is dispersed in the main phase. The hysteresis measurement indicates that the specific saturation magnetization of Sm3+ doped sample is bigger than that of the undoped one. The addition of Sm3+ in Co(2)Z ferrite can decrease the real part mu' and the imaginary part mu of complex permeability, but increase significantly the cutoff frequency. The Sm3+ doped Co(2)Z ferrites sintered at 1250 degrees C exhibited excellent high frequency properties such as high cutoff frequency above 1.8 GHz and higher initial permeability up to 5.