Sonochemical Synthesis of Amorphous Yttrium Iron Oxides Embedded in Acetate Matrix and their Controlled Thermal Crystallization toward Garnet (Y3Fe5O12) and Perovskite (YFeO3) Nanostructures

Sonolysis of stoichiometric mixtures of tris(2,4-pentanedionato)iron, Fe(acac)3, and tris(2,4-pentanedionato)yttrium, Y(acac)3(H2O)3, under Ar atmosphere in tetraglyme led to a colloidal solution from which amorphous Y−Fe−O nanopowders could be precipitated by hexane. These powders are composed of amorphous nanoparticles (3 nm) of yttrium iron(III) oxide embedded in an acetate matrix as proved by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), mass spectrometry, and Mossbauer and IR spectroscopy. The increasing amount (0, 2, 6%) of added water in the reaction mixture was found to lower the organics content in the sonochemical products. The thermally induced crystallization of the amorphous Y−Fe−O nanoparticles was studied by thermal analysis (TG/ DSC), evolved gas analysis (EGA), high-temperature XRD, and Mossbauer spectroscopy. Depending on the Y/Fe starting stoichiometric ratio in the sonicated reaction mixture, the single-phase YFeO3 (YIP) with the p...