Nanocrystalline Zn0.5Ni0.5Fe2O4

Abstract

Zn0.5Ni0.5Fe2(C2O4)3·6H2O was synthesized by solid-state reaction at low heat using ZnSO4·7H2O, NiSO4·6H2O, FeSO4·7H2O, and Na2C2O4 as raw materials. The spinel Zn0.5Ni0.5Fe2O4 was obtained via calcining Zn0.5Ni0.5Fe2(C2O4)3·6H2O above 773 K in air. The Zn0.5Ni0.5Fe2(C2O4)3·6H2O and its calcined products were characterized by thermogravimetry and differential scanning calorimetry (TG/DSC), Fourier transform FT-IR, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), and vibrating sample magnetometer (VSM). The result showed that Zn0.5Ni0.5Fe2O4 obtained at 1073 K had a saturation magnetization of 86.7 emu g−1. The thermal process of Zn0.5Ni0.5Fe2(C2O4)3·6H2O experienced three steps, which involved the dehydration of the six crystal water molecules at first, and then decomposition of Zn0.5Ni0.5Fe2(C2O4)3 into Zn0.5Ni0.5Fe2O4 in air, and at last crystallization of Zn0.5Ni0.5Fe2O4. Based on KAS equation, and OFW equation, the values of the activation energies associated with the thermal process of Zn0.5Ni0.5Fe2(C2O4)3·6H2O were determined to be 126.02 ± 23.93, and 259.76 ± 18.67 kJ mol−1 for the first, and second thermal process steps, respectively. Dehydration of the six waters of Zn0.5Ni0.5Fe2(C2O4)3·6H2O is multi-step reaction mechanisms. Decomposition of Zn0.5Ni0.5Fe2(C2O4)3 into Zn0.5Ni0.5Fe2O4 could be simple reaction mechanism, probable mechanism function integral form of thermal decomposition of Zn0.5Ni0.5Fe2(C2O4)3 is determined to be g(α) = [−ln(1 − α)]4.