Core-shell Nanostructured Nanopowders along(CeO_x)_x(Al2O3)_(1-x) Tie-Line by Liquid-Feed Flame Spray Pyrolysis(LF-FSP)

摘要

We report here the synthesis of(CeO_x)_(1-x)(Al2O3)_x mixed-metal oxide nanopowders with molar ratios that span the CeO_x-Al2O3 composition range.Liquid-feed flame spray pyrolysis(LF-FSP) of mixtures of N(CH2CH2O)3Al(alumatrane) and Ce(O2CCH2CH3)(OH) precursors dissolved in ethanol were aerosolized with O2,combusted at temperatures of 1500-2000 °C and rapidly quenched thereafter to provide(CeO_x)_(1-x)(Al2O3)_x nanopowders of selected compositions.All powders exhibit average particle sizes(APSs)<20 nm and corresponding surface areas of>=50 m2/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 delta-alumina lattice at the lowest concentrations and Ce-magnetoplumbite(CeAl11O18) at 5-10 mol% CeO_x concentrations.