Preparation of superparamagnetic ZnFe2O4 submicrospheres via a solvothermal method

Superparamagnetic Zinc ferrite submicropheres are firstly synthesized via a one-pot solvothermal approach at 200-215°C for 4-8 hours. ZnCl₂, FeCl₃ and NaAc are used as precursors with ethylene glycol solvent. The X-ray diffraction (XRD) data indicate that ZnFe2O4 nanoparticles with the grain size around 15±3 nm can be successfully synthesized via the one-pot method. The scanning/transmission electronic microscope (SEM/TEM) images further show the samples are submicrospheres self-assembled by nanoparticles with size about 375-500 nm changed with reaction conditions. Room-temperature vibration magnetic strength measurements (VMS) demonstrates the as-obtained ZnFe₂O₄ submicrospheres show prefect superparamagnetism, whose coercivity force and remanence are practically nil. The reaction temperature and time influence on the crystallinity, diameter, saturated magnetic intensity and morphology of the particles.