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|Title:||The self-catalytic role of zirconium w-propoxide in sol-gel syntheses of ZrO2-SiO2 mixed oxides|
|Authors:||Zhan, Z. |
|Citation:||Zhan, Z.,Zeng, H.C. (1999). The self-catalytic role of zirconium w-propoxide in sol-gel syntheses of ZrO2-SiO2 mixed oxides. Journal of Materials Chemistry 9 (10) : 2647-2652. ScholarBank@NUS Repository.|
|Abstract:||The self-catalytic role of zirconium n-propoxide (ZP) has been investigated with respect to the synthetic parameters of ZrC2-SiO2 binary gels. It is found that gelation time can be shortened with a high concentration of tetraethoxysilane (TEOS) in the presence of a small amount of ZP. There are two different gelation regions depending on the amount of water added. When ZP is prehydrolyzed, the gelation time is prolonged, resulting in a more transparent gel. Based on the amount of water consumed, it is known that the hydrolysis is a relatively fast process for the ZP-TEOS sols. The mixing level of calcined binary metal oxides has been investigated by FTIR. A linear correlation between the mixing level and metal content holds up to 50 mol% of ZrU2 under the studied conditions. For a low Zr content system, the mixing level of the metal oxides is almost independent of water concentration, whereas for a higher Zr content system, high water concentration is beneficial to the formation of Zr-O-Si hetero-linkages. On the basis of the synthetic data, a mechanism for the ZP-catalytic reactions has been proposed. Condensation rates of hydrolyzcd products are addressed and their effect on the gel homogeneity and oxide mixing level are also discussed.|
|Source Title:||Journal of Materials Chemistry|
|Appears in Collections:||Staff Publications|
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