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Synthesis of metastable phases in the Magnesium Spinel-Alumina System
T.R. Hinklin, R.M. Laine
nanopowders, mixed-metal oxides, metastable spinel phases
We report here the use of liquid-feed flame spray pyrolysis (LF-FSP) to produce fourteen nanopowders along the Al2O3-MgAl2O4 tie line by combusting varied ratio aerosolized ethanol solutions of alumatrane [Al(OCH2CH2)3N] and magnesium acetylacetonate [Mg(C5H7O2)2]. The resulting nanopowders were characterized by X-ray fluorescence, N2 adsorption (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared spectroscopy (FTIR). The powders typically consist of single-crystal particles < 40 nm diameter and specific surface areas (SSAs) of 30-80 m2/g. Complementary XRD and FTIR studies show a gradual change in powder patterns and spectra from δ-Al2O3 to MgAl2O4. Intermediate compositions exhibit phases which fall well outside of the established phase diagram and provide insight into the structure of transition aluminas. These materials have been shown to exhibit novel photonic behavior and have potential value as a new catalyst or support.
Chem. Mater.
2008
20
553-558
article