Synthesis and microstructure of Co/Ni: MgGa2O4 nanoparticles

This report discusses the preparation and microstructure of Co/Ni co-doped MgGa 2 O 4 nanoparticles. The nanoparticles with the size of 20–55 nm were synthesized by sol-gel method. The phase and crystallinity were confirmed by X-ray powder diffraction (XRD) pattern. The particle size was estimated according to XRD data and transmission electron microscopy. The electronic structure was studied using X-ray photoelectron spectroscopy (XPS). The XPS studies showed that Ga 3+ ions possess tetrahedral and octahedral sites of spinel structure and the inverse degree (two times of the fraction of tetrahedral Ga 3+ ions) has increased with the increase of the doping concentration of Co 2+ and Ni 2+ ions. For Co/Ni co-doped MgGa 2 O 4 , two broad absorption bands of 350~500 and 550~700 nm were observed in the absorption spectra. The broad band at 350~500 nm was assigned to the combination of the absorption of octahedral Co 2+ and Ni 2+ ions, whereas the absorption band at 550~700 nm is mainly due to tetrahedrally coordinated Co 2+ ions and octahedrally coordinated Ni 2+ ions.