Preparation and Characterization of Opacified Silica Aerogels Doped by TiO<TEX>$_2$</TEX>

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J. Korean Ceram. Soc. > Volume 36(2); 1999 > Article

Journal of the Korean Ceramic Society 1999;36(2): 159.

TiO$_2$ 첨가에 의한 불투명한 실리카 에어로겔의 합성 및 특성화

손봉희, 현상훈

연세대학교 세라믹공학과

Preparation and Characterization of Opacified Silica Aerogels Doped by TiO$_2$

ABSTRACT

The physical properties and microstructural changes with heat-treatment of opacified silica aerogels doped by TiO2 were investigated. Monolithic SiO2-TiO2 aerogels were prepared by supercritical drying (25$0^{circ}C$, 1250 psig) of wet gel obtained by adding titanium isopropoxide to prehydrolyzed TEOS-isopropanol solutions. The density and the porosity of SiO2-10 mol% TiO2 aerogels were 0.23 g/㎤ and 90%, respectively. During supercritical drying, the linear shrinkage of aerogels increased with increase in the titanium content an TiO2 was transformed to the anatase phase as well as particls agglomerates led to TiO2 clusters of 100~800 nm dispersed homogeneoulsy in the silica matrix. The IR transmittance of opacified silica aerogels was very low in the region of wavelengths below 8 ${mu}{textrm}{m}$ compared with pure silica aerogels and SiO2-TiO2 aerogels showed the high thermal stability of microstructures up to $600^{circ}C$.

Key words: Opacified silica aerogel, Titania, Supercritical drying, IR transmittance