Controllable synthesis of ZnFe2O4 sub-microparticles by poly (diallyldimethylammonium chloride)-assisted solvothermal method

Magnetic zinc ferrite (ZnFe 2 O 4 ) sub-microparticles were synthesized using a facile poly (diallyldimethylammonium chloride) (PDDA)-assisted solvothermal method. X-ray diffraction (XRD) results confirm the formation of spinel structure of ZnFe 2 O 4 with crystallite size from 11 to 41 nm. Scanning electronic microscope (SEM) images show that the samples exhibit a spherical-like morphology self-assembled by primary nanoparticles with sizes about 95–345 nm that are changed with reaction conditions. The zeta potential is increased by the addition PDDA, which indicates the colloidal stability of the sub-microparticles. Dynamic light scattering measurement shows that the presence of PDDA significantly decreased the average hydrodynamic size of the sub-microparticles from 349 nm without PDDA to 117.6 nm with 6 mL of PDDA. Vibrating sample magnetometer (VSM) measurements reveal that the samples synthesized with 0 and 2 mL of PDDA exhibit superparamagnetic properties while those synthesized with 4, 6 and 8 mL of PDDA show a ferromagnetic behavior. The reaction time and different amounts of PDDA influence the crystallinity, size, magnetic property and surface area of the ZnFe 2 O 4 sub-microparticles.