Journal ArticleDOI
Silica and silica-titania glasses prepared by the sol-gel process
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TLDR
In this article, the effects of the composition of the initial alcoholic solutions on the gelation of the silica materials and the effect of using different titanium compounds on the formation of silica-titania gels and glasses were investigated.Abstract:
Clear monolithic samples of silica and silica-titania glasses were prepared by the sol-gel process from alkoxides as starting materials. The effects of the composition of the initial alcoholic solutions on the gelation of the silica materials and the effects of using different titanium compounds on the formation of silica-titania gels and glasses were investigated. DTA and TGA revealed losses of water and organic volatiles during heat treatment of the gels at lower temperatures (up to 400°C) and the glass transformation and crystallization behaviour at higher temperatures (up to 1500°C). The effects of using atmospheres with varying oxygen contents on the DTA peaks caused by oxidation reactions were also studied.
Structural changes occurring during heat treatment were monitored by infra-red spectroscopy which indicated that the water contents of the glasses after heat treatment to 900°C were about 1000 ppm. Transmission electron microscopy of ion beam thinned foils of a 80 SiO220TiO2 composition showed a microstructure of extremely fine pores for heat treatments up to 1000°C. However, after extended heat treatments above 950–1000°C, the porosity appeared to decrease and a high concentration of fine crystallites of anatase (approximately 100 A in diameter) embedded in a silica-rich glass matrix were obtained.read more
Citations
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Journal ArticleDOI
Hydrolysis of titanium alkoxides: modification of the molecular precursor by acetic acid
TL;DR: In this paper, it was shown that bidentate acetates replace the OR groups and are directly bounded to the titanium, leading to Ti(OR) x (Ac) y. oligomers.
Journal ArticleDOI
Gel technology in ceramics
TL;DR: The use of sol-gel techniques to prepare ceramic materials ranks high among those areas in ceramic science and technology which are changing most rapidly and which offer the greatest promise for outstanding improvements in both understanding and applications as mentioned in this paper.
Journal ArticleDOI
Raman scattering characterization of gel-derived titania glass
TL;DR: In this paper, the preparation of bulk vitreous TiO2 is reported and its transformation both by controlled thermal treatment and by laser-induced heating in the anatase and rutile crystalline forms is studied by Raman spectroscopy.
Journal ArticleDOI
Gel technology in ceramics, glass-ceramics and ceramic-ceramic composites☆
TL;DR: The use of sol-gel routes has been widely used for many centuries in earthenware and china production and history points out that progress is due to the "wedding" of (inorganic and organic) chemistry with ceramics as mentioned in this paper.
Journal ArticleDOI
Sol-gel transition in the hydrolysis of silicon methoxide
TL;DR: In this article, the sol-gel transition in the hydrolysis of silicon methoxide in acidic, basic and neutral pH media has been investigated by means of gas chromatography and small angle X-ray scattering measurements to elucidate the effect of a catalyst on gelling time and the properties of the obtained gel.
References
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Journal ArticleDOI
Alumina gels that form porous transparent Al2O3
TL;DR: In this paper, the authors discuss the requirements for a porous transparent Al2O3 from aluminium alkoxides to retain its integrity during drying and pyrolysis, and show that there is a critical electrolyte concentration at which the gelling volume goes through a pronounced minimum.
Journal ArticleDOI
Structural Evaluation of Silicon Oxide Films
W. A. Pliskin,H. S. Lehman +1 more
TL;DR: In this paper, it has been established that by the use of infrared absorption spectroscopy, preferential etching procedures, precise optical measurements of thickness, density, and refractive indices, and carefully chosen environmental tests, differences in the oxide films can be determined.
Journal ArticleDOI
New Routes to Multicomponent Oxide Glasses
TL;DR: In this paper, the authors proposed a method for the production of thin, transparent multicomponent oxide layers of almost any composition on substrates using only up to the transformation range of the glass in question, usually 500-600 °C.
Journal ArticleDOI
Glasses from metal alcoholates
Sumio Sakka,Kanichi Kamiya +1 more
TL;DR: In this paper, the technique of preparing oxide glasses from metal alcoholates through hydrolysis, gelling and heating at low temperatures has been reviewed, which makes it possible to produce very high purity and compositions which the conventional melting technique could not give because of immiscibility, crystallization and high melting temperatures.
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