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Chemistry for Sustainable Development

2011 year, number 4

Obtaining Nanocrystalline О±-Al2O3 by Introducing a Seeding Agent into Precursors

Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences,
Ul. Kutateladze 18, Novosibirsk 6300128 (Russia)
Keywords: О±-aluminium oxide, nanopowder, synthesis, caking
Pages: 339–345


By introducing α-Al2O3 powder with particle size 25 nm, in the amount of 1–10 mass %, into the solution of aluminium nitrate or into dry aluminium hydroxide, the kinetics of the formation of the stable α-phase during subsequent heating of the precursor gets accelerated substantially. Depending on the amount and method of introducing the seeding agent, the complete transformation of the precursor into α-Al2O3 occurs at a temperature within the range 800 to 930 °С. The powder formed at such a low temperature is composed of porous aggregates 10–20 mm in size; the size of crystallites comprising the aggregates is independent of the amount of seeding agent introduced and is equal to approximately 50–60 nm. Grinding under soft conditions leads to the destruction of aggregates and to the formation of nanopowder which is active towards caking. Later on, a ceramic material with the porosity at a level of 1 % is obtained from the powder at 1450 °С.