Evaluating eddy current behavior and magnetic loss in pure and Mn/Zn-doped NiFe₂O₄ spinel ferrites

Spinel ferrites of the chemical formula M_xNi_1-xFe₂O₄ (M = Mn, Zn) were prepared by minimum doping or contamination values x = %0, %5 through the co-precipitation process. The samples synthesized by Hydrazine hydrate and ethylene glycol surfactant and were annealed at 800 °C. The XRD, SEM, and TEM analyses were investigated. To investigate the frequency-dependent of magnetic permeability (µ) and magnetic loss in NiFe₂O₄ ferrite, the eddy current and hysteresis loss were measured by impedance spectroscopy and VSM analysis for all samples. In considering the electrical parameters of impedance spectroscopy in the range of 10^-3-10⁶ Hz, the frequency-dependent of real (Z') and imaginary (Z'') part of doped specimens increased and consequently conductivity decreased. All three samples exhibit frequency-dependent dielectric parameters and electric modulus, and might have a potential to react to electromagnetic waves. The µ' value extracted from dielectric data, is negative in low frequency regions and approach nearly zero value by enhancing the frequency for all three samples. The magnetic loss enhanced in doped samples that can be explained by the peak point of eddy current loss in the high frequency range for pure and doped samples. M-H hysteresis loop specified that the saturation magnetization (M_s) increased by Mn and Zn-doped multi-domain Ni ferrite while the coercivity field (H_c) decreased. The hysteresis loss increased in Zn-doped and diminished in Mn-doped Ni ferrite. Other magnetic parameters including: anisotropy constant (K), anisotropy field (H_k), magnetic moment (n_B) and initial permeability µ_i were calculated by hysteresis loop.