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摘要
A novel and versatile synthesis route has been developed to fabricate hollow Al(2)O(3) microspheres with nanoporous shell structures. The method involves a preferential "implantation" of Al species into polymeric template particles to form a core-shell structure in solvent. The template cores can then be removed by thermal pyrolysis to form hollow interiors. This unique "implantation" process allows for synthesis of monodisperse hollow spheres with a nonaggregated character. The implantation of Al species is confirmed by electron spectroscopy for chemical analysis/Auger analysis in depth profiles. The shell structure changes from amorphous to gamma-Al(2)O(3) at 900 degrees C; because of which, the shell is nanoporous in structure. The porous shell then transforms to alpha-Al(2)O(3) as temperature is further raised above 1000 degrees C. Transmission electron microscopy examination reveals a uniform shell thickness of ca. 20-40 nm, and grain growth appears to be constrained by the thin shell walls at 1100 degrees C, leading to void formation at the triple grain junctions.
- 出版日期2009-1
