technique eliminates the difficulties of heating the sample The thermal degradation of zirconia gels prepared from the to dehydroxylation temperatures and quenching before meahydrolysis of modified tetra-n-butoxyzirconium(IV) and subsesurement, because IES measures the dehydroxylation proquent peptization with nitric acid was studied by infrared emission cess as it is actually taking place. In this paper we report spectroscopy. The colloid precursor was modified by equimolar the study of the changes induced in the molecular structure addition of aliphatic acids to the alkoxide. Structural changes are of zirconia gels prepared by the modification of tetra-nreadily observed by in situ collection of spectroscopic data of gels butoxyzirconium(IV) with short-chain aliphatic acids, using at elevated temperatures. Spectra were collected at 25ЊC intervals the IES technique.
over the temperature range 100 to 650ЊC. Structural degradation of the zirconia gel is followed by selection of the appropriate spectral regions. Two bands are observed at 3802.5 and 3834 cm 01 and EXPERIMENTAL are assigned to the zirconia hydrogen-bonded and non-hydrogenbonded hydroxyl stretching vibrations. Five bands, which are as-Preparation of Zirconia Sols and Gels signed to water hydroxyl groups, are observed at 3506, 3422, 3404, Tetra-n-butoxyzirconium(IV) (TBZ) was modified by re-3284, and 3242 cm 01 . The 3506 cm 01 band is attributed to ''free''
water trapped in the zirconia gel. The intensity of this band de-action with acetic and propanoic acids. Table shows the creases rapidly and approaches zero by 300ЊC. The three bands modified precursors that were used in this research. The at 3422, 3404, and 3422 cm 01 are attributed to water in the fixed modified alkoxides were allowed to cool to 25ЊC and then layer of the zirconia gel. The band at 3242 cm 01 is assigned to added slowly, with stirring, to water at 25ЊC. The resulting water coordinated to the zirconium in the gel. The spectra of precipitates were washed several times with water to remove both uni-and bidentate acetates are observed. A model for the organic reaction products, namely alcohols, and then diluted decomposition of the zirconia gel is proposed based on the spectroin water to give slurries with ZrO 2 concentrations of Ç0.6 scopic evidence.