Preparation and Characterization of Zn1-xNixFe2O4 Nanoparticles with Spinel Structure Synthesized by Hydrothermal Method

Background: Among the mixed transition metal oxides, ZnFe2O4 as a binary metal oxide with a spinel structure has a wide range of application prospects in materials science and technology. The microstructure, energy band structure, optical properties and magnetic properties of ZnFe2O4 can be modified by element doping. Objective: In this work, the influences of Ni doping upon the structure, morphology, optical and magnetic properties of ZnFe2O4 were studied. Methods: Pure and Ni-doped Zn1-xNixFe2O4 nanoparticles with different concentration (x = 0, 0.1, 0.3 and 0.5) were successfully synthesized by hydrothermal method. XRD, HRTEM, XEDS, UVvis, FT-IR and VSM were utilized to investigate the Zn1-xNixFe2O4 nanocrystals samples. Results: The experimental results show that all Zn1-xNixFe2O4 nanoparticles have cubic spinel structure with good crystallization. Ni2+ successfully substituted for the lattice site of Zn2+ and generated single-phase ZnFe2O4 without other impurity phases. After Ni doping, the grain size distribution increased, the bandwidth increased and ferromagnetism increased. Conclusion: The crystalline size increased as Ni concentration increased, while its the lattice constant occurshrink expansion. The energy band gap of Zn1-xNixFe2O4 nanocrystals increased as Ni concentration increased, and blue shift occurred compared to that of the pure ZnFe2O4. Pure ZnFe2O4 nanocrystals showed superparamagnetic properties, while the doped Zn1-xNixFe2O4 samples have obvious ferromagnetic properties at room temperature.