Preparation and modification of nano-sized Al₂O₃ powders through addition of oxide

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ÎÄÕÂÒ³Â룺447 - 451

Key words£ºammonium aluminum carbonate hydroxide£» nano ¦Á-Al₂O₃£» ¦Á phase transformation£» doping£» TiO2 sol

Abstract: Ammonium aluminum carbonate hydroxide£¨AACH£©, the precursor of ¦Á-Al₂O₃, was fabricated with NH₄Al£¨SO₄£©₂ and NH₄HCO₃ via a precipitation method. During the heat treatment AACH undergoes such a phase transformation process: amorphous£¨350¤@¡æ£©¡ú¦Ã£¨700¤@¡æ£©¡ú¦Ã+¦È£¨1¤@050¤@¡æ£©¡ú¦È+¦Á £¨1¤@100¤@¡æ£©¡ú¦Á £¨1¤@200¤@¡æ£©. Oxides, such as TiO₂ sol and MgO sol were introduced into the precursor. Then both the ¦Á transformation temperature and the particle sizes of ¦Á-Al₂O₃ are decreased. The microstructures and its surface electronic properties of the powders are modified, and its dispersion property is improved. Doping TiO₂ sol grains, AACH completes ¦Á phase transformation nearly at 1¤@100¤@¡æ, its first-order diameter is about 120¤@nm. Doping with MgO sol grains, ¦Á phase transformation completes after being sintered at 1¤@100¤@¡æ.