SURFACE CHARACTERIZATION OF ZRO2-SIO2 SYSTEMS PREPARED BY A SOL-GEL METHOD

Gels with composition xZrO2 . (100 X)SiO2, x = 3-100 mol%, were prepared by a sol-gel method, using zirconyl chloride and commercial silica gel. Gels treated at different temperatures up to 1000-degrees-C were previously characterized by a combination of differential thermal analysis (DTA) and X-ray diffraction techniques. Surface characterization by means of infrared spectroscopy (IR), water-temperature-programmed desorption combined with mass spectroscopy (TPD-MS), UV-visible diffuse reflectance spectroscopy (UV-V/DR) and scanning electron microscopy (SEM) is reported here. The crystallization is metastable-cubic/tetragonal zirconia occurred only when the zirconia gel was dispersed in the silica matrix. In the absence of silica gel, the prepared zirconia gel developed the monoclinic crystalline phase following thermal treatment. Bulk zirconium dioxide exhibited both basic and acid hydroxyl groups, the basic hydroxyl groups were lost by depositing zirconium oxide on SiO2. Changes observed in UV-V absorption spectra are also reported.