Preparation of γ-Fe(2)O(3)/ZnFe(2)O(4) nanoparticles by enhancement of surface modification with NaOH

BACKGROUND: During liquid-phase synthesis of γ-Fe(2)O(3) nanoparticles by chemically induced transition in FeCl(2) solution, enhancement of surface modification by adding ZnCl(2) was attempted by using NaOH. By using transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectrometry, and vibrating sample magnetometry, the dependence of the synthesis on the amount of additional NaOH was studied. RESULTS: The experimental results show that the surface of the γ-Fe(2)O(3) nanoparticles could be modified by adding ZnCl(2) to form composite nanoparticles with γ-Fe(2)O(3)/ZnFe(2)O(4) ferrite core coated with Zn(OH)(2) and adsorbed FeCl(3), and that modification could be enhanced by adding NaOH. CONCLUSIONS: In the experimental conditions, when the concentration of additional NaOH was below 0.70 M, the amounts of ZnFe(2)O(4) and Zn(OH)(2) phases increased slightly and that of adsorbed FeCl(3) was unchanged. When the concentration of NaOH exceeded 0.70 M, the amount of FeCl(3), ZnFe(2)O(4), and Zn(OH)(2) increased.