Size-controlled synthesis of nanoscaled aluminium spinels using heterobimetallic alkoxide precursors via water/oil microemulsions

Nanosized spinels of type MAl2O4 (M = Mg, Co, Ni, Cu) were prepared by a so l-gel type hydrolysis of alkoxides in the inverse micelles of w/o microemul sions. Heterobimetallic alkoxides M[AI(OPri)(4)](2) containing both metalli c elements in the desired stoichiometric ratio were employed as single-sour ce precursors. The structure and thus metal stoichiometry in the molecules was established by single crystal X-ray diffraction analysis. By varying th e hydrophilic chain length of the detergent, the diameter of the water drop lets can be tuned in the nanometer range, as determined by dynamic light sc attering. The size of the resulting spinel nano-particles as evaluated from XRD peak profile analysis, correlates to the droplet size. The results of the ceramic syntheses using the different types of alkoxide precursors were compared which reveal the advantage of a single source approach. (C) 1999 Acta Metallurgica Inc.