K J D Mackenzie
Articles written in Bulletin of Materials Science
Volume 23 Issue 4 August 2000 pp 301-304 Material Synthesis
Aluminium hydroxides have been precipitated from various aluminium salts and the differences in their thermal behaviour have been investigated. Pseudoboehmite derived from the nitrate, sulfate and chloride all form γ-Al2O3 at ∼ 400°C but the formation of α-A12O3 at 1200°C occurs more readily in the material derived from the sulfate. This contains a higher concentration of anionic impurities related to differences in the solubility of the original aluminium salts. The sulfate is retained in the gel to higher temperatures at which its eventual decomposition may lead to the formation of a reactive pore structure which facilitates the nucleation of α-A12O3.
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