Microstructures and High Frequency Properties of ${\hbox {Sm}}^{3+}$ Doped ${\hbox {Co}}_2{\hbox {Z}}$

The Sm³⁺ doped Co₂Z-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 Co₂Z-type hexaferrite is still in the main phase of the Co₂Z 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 Co₂Z ferrite can decrease the real part μ´ and the imaginary part μ^´´ of complex permeability, but increase significantly the cutoff frequency. The Sm³⁺ doped Co₂Z ferrites sintered at 1250°C exhibited excellent high frequency properties such as high cutoff frequency above 1.8 GHz and higher initial permeability up to 5.