Synthesis and characterization of spinel-type zinc aluminate nanoparticles by a modified sol-gel method using new precursor

Research highlights: → Modified sol-gel method for synthesis of spinel-type zinc aluminate nanoparticles. → Zn(en)22+ complex (en = ethylenediamine) as new Zn2+ source. → Effect of reaction temperature on the particle size. - Abstract: In the present paper, we report the successful synthesis of spinel-type of zinc aluminate (ZnAl2O4) nanoparticles by a modified sol-gel method. Aluminum nitrate and Zn(en)2+ complex (en: ethylenediamine) as new Zn2+ source were used. Diethylene glycol monoethyl ether and citric acid are employed as solvent and chelating agent. This method starts from the precursor complex, and involves formation of homogeneous solid intermediates, reducing atomic diffusion paths during thermal treatment. ZnO and ZnAl2O4 nanocrystals were obtained when the precursor was heat-treated at 350 deg. C in air for 2 h. The stages of the formation of ZnAl2O4, as well as the characterization of the resulting compounds were done using thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The structure, particle size, and temperature of formation of ZnAl2O4 phases were found to depend on the precursors and methods used for preparation and the calcination temperature. The lowest temperature for preparation of the ZnAl2O4 is about 550 deg. C.