Mixed-metal tert-butoxide, [CoGa2(OtBu)8], was employed in the chemical vapor deposition (CVD) and sol-gel processes to obtain thin films and nanoparticles of spinel CoGa2O4phase, respectively. The appropriate Co:Ga ratio and intact vaporization (115-120 °C / 10-2Torr) of the molecular source produced crystalline deposits of CoGa2O4at relatively low temperatures (~ 500 °C). A clean transformation of the heterometal precursor in spinel oxide of definite composition was supported by TG/DTA analysis that showed no weight loss above 470 °C. The SEM images of CoGa2O4films showed homogeneous morphology and dense microstructure constituted by nanometric grains (, ~ 35 nm). Hydrolytic decomposition of the precursor produced gels that upon heat-treatment (400-1200 °C) formed nanoscaled spinel. For comparison, CoGa2O4was also prepared by complexing Co2+and Ga3+ions with glycolate ligands, significant agglomeration effect, broader size dispersion and amorphous domains were observed indicating that low-temperature synthesis of monophasic materials following conventional chemical approaches is hampered by thermodynamic impediments. The UV/Vis spectra of CoGa2O4particles exhibit characteristic peaks corresponding to4A2(F)à4T1(P) transition in the divalent cobalt cation. The magnetization data of the CoGa2O4nanoparticles showed as expected an antiferromagentic behavior.
