No abstract

The DC-bias superposition characteristics of NiCuZn ferrite with different amount of Bi2O3 have been investigated. The microstructure depends much on the amount of Bi2O3. The DC-bias-superposition characteristics have great relationship with the microstructure. The permeability of materials composed of tiny grains decreases more slowly with the increase of DC-bias superposition due to the absence of the domain walls in the grain. The nonmagnetic phase in the grain boundary can reduce the actual DC-bias superposition in the grains when the sample was subject to DC-bias superposition. In short, a microstructure with relatively small average grain size and thick nonmagnetic phase in the grain boundary, which is favorable for obtaining better DC-bias superposition characteristics.

A square coil antenna with a resonance frequency of 13.56MHz was proposed. Simulation analysis has been made to evaluate how the soft magnetic materials’ dimensions and the real part of permeability affect the shielding performance. The results show that the soft magnetic material with a larger or thicker dimension or with a higher real part of permeability has a better performance in shielding metals.

The Co2Z ferrites noise suppression sheet was prepared by tape casting. Its microstructural characterization was performed by electron microscopy and noise suppression effect was measured by a microstrip line method. Results indicate that as the sinter temperature increases, the imaginary permeability increases leading to the enhancement of the suppression capability, and the thickness of noise suppression sheets also contribute to the noise suppression capability.