Sintering, microstructures and magnetic properties of low temperature co-fired NiCuZn ferrites with B2O3 and WO3 additions

• Small amount of B2O3 and WO3 additions can dramatically enhance densification.
• The initial permeability is almost double with B2O3 and WO3 additions.
• We examine variation of microstructures and Curie temperature.
• Appropriate additions can greatly improve the magnetic properties.

Sintering behaviors and magnetic properties of the NiCuZn ferrites with different B2O3 and WO3 additions are investigated. The initial permeability values of the ferrites with 0.03 wt% B2O3 go up firstly from 788.77 to 913.46 as WO3 concentration increases from 0.3 to 0.7 wt%, then drop to 458.48 for the composition with 0.9 wt% WO3. But too much B2O3 or WO3 will damage the magnetic properties. The appropriate additions of mixed B2O3 and WO3 not only can efficiently increase the initial permeability (μi) and the saturation flux density value (Bs), but also can reduce the remanent flux density value (Br) and the coercive filed strength (Hc) of the NiCuZn ferrites sintered at 900 °C. The ferrite sample with 0.03 wt% B2O3 and 0.7 wt% WO3 possesses optimum magnetic properties: μi = 913.46 at 100 kHz, Bs = 284.36 mT, Br = 103.96 mT and Hc = 38.39 A m−1.

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