Magnetic properties and crystallization kinetics of Zn0.5Ni0.5Fe2O4

Precursor of nanocrystalline Zn_0.5Ni_0.5Fe₂O₄ was obtained by grinding mixture of ZnSO₄·7H₂O, NiSO₄·6H₂O, FeSO₄·7H₂O, and Na₂CO₃·10H₂O under the condition of surfactant polyethylene glycol (PEG)-400 being present at room temperature, washing the mixture with water to remove soluble inorganic salts and drying it at 373 K. The spinel Zn_0.5Ni_0.5Fe₂O₄ was obtained via calcining precursor above 773 K. The precursor and its calcined products were characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The result showed that Zn_0.5Ni_0.5Fe₂O₄ obtained at 1073 K had a saturation magnetization of 74 A·m2·kg−1. Kinetics of the crystallization process of Zn_0.5Ni_0.5Fe₂O₄ was studied using DSC technique, and kinetic parameters were determined by Kissinger equation and Moynihan et al. equation. The value of the activation energy associated with the crystallization process of Zn_0.5Ni_0.5Fe₂O₄ is 220.89 kJ·mol⁻¹. The average value of the Avrami exponent, n, is equal to 1.59±0.13, which suggests that crystallization process of Zn_0.5Ni_0.5Fe₂O₄ is the random nucleation and growth of nuclei reaction.