Microwave sintering versus conventional sintering of NiCuZn ferrites. Part II: Microstructure and DC-bias superposition characteristics

NiCuZn ferrites with the composition of (Ni0.48Cu0.10Zn0.42O)1.04(Fe2O3)0.96 were consolidated by microwave sintering (MS) and conventional sintering (CS), respectively. The influences of external microwave field and additives (1 wt% BSZ glass or 1 wt% Bi2O3) on the microstructure and DC-bias superposition characteristics of NiCuZn ferrites were investigated. Experimental results demonstrated that the final grain size was much larger with higher density since applying microwave field. In addition, for undoped ferrites, coarse grains structure obtained from microwave sintering is harmful to the DC-bias superposition characteristics. However, since adding BSZ glass or Bi2O3, the discrepancy on the final grain size obtained from MS and CS methods is not obvious. NiCuZn ferrites with the addition of BSZ glass or Bi2O3 exhibited a stronger ability to inhibit the drop of permeability under the DC-bias magnetic field. Possible mechanisms behind are discussed in this article.