Core−shell Nanostructured Nanopowders along (CeOx)x(Al2O3)1−xTie-Line by Liquid-Feed Flame Spray Pyrolysis (LF-FSP)

We report here the synthesis of (CeO x ) 1− x (Al 2 O 3 ) x mixed-metal oxide nanopowders with molar ratios that span the CeO x −Al 2 O 3 composition range. Liquid-feed flame spray pyrolysis (LF-FSP) of mixtures of N(CH 2 CH 2 O) 3 Al (alumatrane) and Ce(O 2 CCH 2 CH 3 )(OH) precursors dissolved in ethanol were aerosolized with O 2, combusted at temperatures of 1500−2000 °C and rapidly quenched thereafter to provide (CeO x ) 1− x (Al 2 O 3 ) x nanopowders of selected compositions. All powders exhibit average particle sizes (APSs) < 20 nm and corresponding surface areas of ≥50 m 2 /g when produced at rates of 100−300 g/h. The as-processed powders were characterized in terms of phase, size, specific surface area, composition, and morphology by BET, XRD, XRF, SEM, TEM, STEM, XEDS, XPS, FT-IR, and TGA-DTA. Surprising core−shell nanostructured nanopowders are observed in the Ce−Al−O system at CeO x rich concentrations (≥15 mol %). In addition, evidence is presented for the incorporation of Ce 3+ ions in the δ-alumina lattice at the lowest concentrations and Ce-magnetoplumbite (CeAl 11 O 18 ) at 5−10 mol % CeO x concentrations.