ISSN:
1573-4846
Schlagwort(e):
zirconia
;
hydrolysis kinetics
;
precursor chemistry
;
zirconium alkoxides
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract The formation of zirconia colloids by hydrolysing zirconium n-propoxide in n-propanol has been investigated by simultaneous, multi-angle static and dynamic light scattering, and vibrational spectroscopy, as a function of reactant concentration, water-to-alkoxide mole ratio and temperature. The overall hydrolysis/condensation reaction followed pseudo 2nd-order kinetics at 303 K, with an induction period of 〈1 to 24 hours. The induction period could be substantially reduced by increasing the temperature to 348 K. For hydrolysis with 3.6 moles of water per mole of alkoxide, the apparent activation energy was 24 kJ mol−1. Such a low activation energy implies that hydrolysis occurs readily over the temperature range investigated (303–348 K). During the induction period, processing with stoichiometric, or excess, water produced “oxy-hydroxides”, while “hydrated oxides” formed under water-deficient conditions. The hydrolysis reactions yielded zirconia colloids with equivalent spherical, z-averaged diameters of 〈200 nm. The colloids exhibited fractal dimensions of 3.0, with a low size-polydispersity, inferring the formation of dense, monodispersed spherical particles. SEM observations confirmed these results.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00486244
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