| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1530709 | Materials Science and Engineering: B | 2009 | 4 Pages |
NiCuZn ferrite materials fired at low temperature and containing 1.5 wt.% Bi2O3 and different Co2O3 concentrations have been prepared by the conventional ceramic technique. The samples were sintered for 4 h in air at 900 °C. The initial permeability decreased with the Co2O3 content due to local anisotropy induced by Co ions. The saturation magnetization increased with the Co2O3 content, which is attributed to the preference of Co ions for octahedral sites and their higher magnetic moment than those of Ni and Cu ions. Power loss under excitation at low magnetic flux density and low frequency first decreased, and then increased with increasing Co2O3 content due to the collective influence of the local induced anisotropy and the initial permeability. When the excitation frequency increased to 1 or 10 MHz, the power loss gradually decreased with increasing Co2O3 content, mainly because Co ions can decrease the concentration of Fe2+ leading to a decrease in eddy current loss and residual loss for the ferrite samples. With increasing induction flux density, the effect of domain wall “freezing” caused by Co ions gradually disappears. For a flux density greater than or equal to the critical value of 50 mT, Co2O3 addition has a negative influence on decreasing the power loss of NiCuZn ferrites fired at low temperature.
