Effects of the Sintering Temperature on RF Complex Permeability of NiCuCoZn Ferrites for Near-Field Communication Applications

The effect of bismuth oxide (Bi
₂
O
₃
) and sintering temperature on NiCuCoZn ferrite powders has been investigated for the near-field communication applications. The powders were prepared by conventional solid-state synthesis method. The microstructure and frequency-dependent complex permeability were investigated. Employment of Bi
₂
O
₃
as a sintering aid promotes uniform grain growth and densification in sintered powders, which in turn has affected complex permeability spectra. It has been observed that the addition of Bi
₂
O
₃
decreases permeability and magnetic loss from 147 to 110 and from 0.03 to 0.02, respectively, which were both sintered at 1100 °C and measured at 13.56 MHz frequency as compared to undoped sample (without Bi
₂
O
₃
). Also, permeability and magnetic loss were increased with sintering temperature. Complex permeability and resonance frequency follow the Globus model.