Initial permeability studies of Ni-Zn ferrites prepared by flash combustion technique

The initial permeability (μ_i) and relative loss factor (tan δ/μ_i) of Ni-Zn ferrite of composition Ni_0.8Zn_0.2Fe₂O₄ prepared by the non-conventional flash combustion technique are studied and reported. The ferrite powder prepared by this technique was calcined at 900 °C and the uniaxially pressed samples were sintered at various temperatures 1150, 1250 and 1350 °C. The initial permeability and the relative loss factor have been studied as the function of testing frequency and temperature. It is observed that the Ni-Zn ferrites prepared by this technique have the initial permeability from 16 to 20 in the frequency range 1 kHZ to 13 MHz and the relative loss factor of 10³-10⁴ in the frequency range 100 kHZ to 13 MHz. The initial permeability increases from room temperature to 300 °C. The relative loss factor is of the order of 10^-2. The results obtained are better when compared with ferrites prepared by the conventional ceramic method. This is attributed to better purity, controlled microstructure and chemical homogeneity achievable by the flash combustion method. Low relative loss factor makes these ferrites particularly useful as inductor and transformer materials for high frequency applications.