Facile synthesis of aluminum-containing mixed-metal oxides using doped carboxylate alumoxane nanoparticles

A simple and rapid process has been developed that allows the formation of highly crystalline main-group, lanthanide, and transition-metal aluminates, including CaAl12O19 (hibonite), Y3Al5O12 (yttrium aluminum garnet, YAG), LaAl11O18, LaAlO3, Ce2Al3O8, NdAlO3, Er6Al10O24, and Al2TiO5, Carboxylate-stabilized alumina nanoparticles (carboxylate alumoxanes) are reacted with the appropriate metal acetylacetonate complexes to form metal-doped carboxylate alumoxanes and aluminum acetylacetonate via a facile transmetalation reaction. Thermolysis of the metal-doped carboxylate alumoxanes, up to a temperature of 1400 degrees C, yields crystalline aluminates, as confirmed by X-ray diffractometry, electron microprobe analysis, and scanning electron microscopy. The synthesis of different phases (i.e., LaAl11O18 versus LaAlO3) is controlled by the stoichiometry of the transmetalation reaction. A new, distorted, perovskite phase (with lattice parameters of a = 5.47 Angstrom and c = 13.3 Angstrom) of LaAlO3 is formed. The alumoxane methodology results in multicomponent aluminate materials that are obtained in shorter processing times and with greater phase purity than previously reported. This observation is undoubtedly due to the atomic-scale miring that is inherent in the alumoxane nanoparticle approach.