Introduction of Structural Variations into Oxide Polymers and their Effect on Sintering and Crystallization

摘要

Hydrolytic polycondensation of metal alkoxides produces polymeric units consisting of an oxide network framed by hydroxyl and organic groups. The morphology of the polymerization as well as the structure of these materials is determined by the kinetics of hydrolysis polymerization reactions. By controlling the kinetics of these reactions it is possible to produce modified ceramic materials with altered properties. In this work, by using three representative systems, i.e., silica, titania and zirconia, the effect of hydrolytic polycondensation parameters on the resultant materials was investigated. These parameters include: molecular separation of species, their ratios, the reaction medium, the concentration of catalyst, the reaction time, the temperature and the type of alkyl group in the alkoxide. In the silica system, the parameters that affect the hydrolytic polycondensation of titanium alkoxides Ti(OR)4 were investigated. In the zirconia system, it has been shown that the alkyl groups and molecular separation during the hydrolytic condensation have particular significance in the modification of the monoclinic tetragonal transformation of the resultant ZrO2.