| Popis |
We studied sonochemical synthesis of yttrium, lanthanide and uranium oxides and phosphates from solutions of particular metal precursors, such as metal nitrates, acetates, and acetylacetonates, in organic solvents. Nonaqueous solvents, such as tetraglyme (tetraethyleneglycol dimethylether, TGL) and trialkylphosphates, OP(OR)3, R = Me (TMP), Et (TEP), nBu (TBP), were employed. Phosphates served both as solvents and reactants. Sonolysis provided amorphous precipitates that were converted to particular metal oxides and phosphates by calcination. All obtained precipitates were characterized by ICP/OES, by nitrogen adsorption isotherms, by DLS, IR spectroscopy, SEM, TG/DSC analysis and powder XRD analysis. Sonolysis of a series of uranyl nitrate, acetate, and acetylacetonato complexes, M(acac)3, M = Y, La, Ce, Pr, Nd, Eu, Dy, Er, and UO2(acac)2 was carried out in TGL, TMP, TEP, and TBP under Ar on a Sonics and Materials VXC 500 W and working frequency of 20 kHz. The precursors (0.50 g) were dissolved in 50 cm3 of a solvent, purged with Ar and cooled with a Julabo F 25MP thermostat. Sonication was run for 8 h under Ar. The product was precipitated by the addition of hexane (20 cm3) and the solid was separated from the solvents by centrifugation on a Heraeus Labofuge 400 at 3000 rpm. The powders were washed by isopropanol and light petroleum and left to dry in open air. The sonolysis of M(acac)3 in TGL provided amorphous powders with major bands in their IR spectra which correspond to vas(COO) a vs(COO) vibrations of acetates produced by the acac ligand decomposition. Powders featured high surface areas up 380 m2/g established by BET analysis. Calcination of the powders to 1000 oC in air led to the formation of U3O8, CeO2, Pr6O11, and corresponding Ln2O3 oxides identified by their XRD powder patterns. When reactions of the same set of precursors were carried out ing a reactive solvents TMP, TEP, and TBP, we were able to obtain Y(PO3)3, UP2O7, and a series of LnPO4 phases.
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