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Chemistry for Sustainable Development

2013 year, number 6

Features of the Crystallization of Aluminohydroxide Gel Containing Mechanochemically Prepared Nanosized О±-Al2O3 Particles

G. R. KARAGEDOV1, S. S. KOSOLOBOV2, A. V. LATYSHEV2, N. Z. LYAKHOV1 and A. L. MYZ1
1Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Ul. Kutateladze 18, Novosibirsk 630128 (Russia)
E-mail: garik@solid.nsc.ru
2Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Pr. Akademika Lavrentyeva 13, Novosibirsk 630090 (Russia)
Keywords: aluminium oxide, nanopowder, synthesis, mechanochemistry
Pages: 603–608

Abstract

The introduction of α-Al2O3 nanoparticles into the gel formed during the hydrolysis of aluminium nitrate causes a substantial decrease in the temperature of its transition tino thermodynamically stable modification. The higher is the concentration of seeding within the range 0.2–5 mass %, the lower is the temperature of the formation of monophase α-Al2O3. At the sme time, the temperature of phase transition into the α-modification depends on the method of introduction of the seeding into the gel. This may be connected with nonuniform distribution of nanoparticles over its volume. The use of deionized water as a solvent instead of distilled water allows decreasing the temperature of α-Al2O3 formation to 500 °C. Due to the low temperature of the formation of a-phase (<950 °C), the product consists of easily destroyable granules formed by nanoparticles 45–60 nm in size. Nevertheless, the samples formed from powders with close size demonstrate different sintering ability during low-temperature annealing in the air (1300 °C). Their densities vary within the range 67–97 % of the theoretically possible value. This is likely to be connected with the fact that separate particles in granules get grown together under unfavourable conditions.