Effect of calcination on the magnetic permeability of (Ni0.21Zn0.58Cu0.23)Fe1.95O4 ferrite prepared using the sol–gel self-propagated technique

(Ni0.21Zn0.58Cu0.23)Fe1.95O4 ferrite was prepared by sol–gel self-propagating method. It was found that the calcination were effective to remove the residual and other phases arising from the inadequate combustion of the gel, which promoted the solid-reaction in the sintering process and finally led to a denser and more uniform microstructure of the sintering body. So the magnetic properties of the calcined ferrites were improved significantly, especially the quality factor. At 100 kHz, the quality factor of sintered ferrite calcined was found to be about 80, which was four times higher than that of sintered ferrite without calcination.