Effects of Lead(II) Oxide on Processing and Properties of Low‐Temperature‐Cofirable Ni‐Cu‐Zn Ferrite

The effects of PbO addition on the densification, microstructure, and properties of low‐temperature cofirable Ni‐Cu‐Zn ferrite have been investigated. With a small amount of PbO (0.5–2 wt%) present as a dopant in the Ni‐Cu‐Zn ferrite, the densification rate and final sintered density are greatly increased, but the activation energy of densification is significantly reduced. These results are attributed to a chemical reaction that occurs at the PbO/Ni‐Cu‐Zn ferrite interface, resulting in a greater amount of liquid phase and good wetting during sintering. However, the above‐mentioned interfacial reaction causes segregation of CuO onto the grain boundary and dissolution of PbO into the ferrite grains, yielding a reduction in initial permeability.