| Summary: | 碩士 === 淡江大學 === 化學工程學系 === 84 === SiO2,TiO2, and their homogeneous mixture with equal molar ratio
were preparedby the sol-gel processing of TEOS and/or TEOT. The
effects of alcoholic solvent(quantity and alkyl chain), water
quantity, esterification reaction, pH, and thermal treatment on
the morphologies and chemical composition were studied using the
x-ray diffraction, thermal analysis, FT-IR spectroscopy,
scanning electron microscopy with elemental mapping, and gas
pycnometry. The results showed that all xerogels obtained were
noncrystalline and contained nanoscale primary particles.
Increasing the solvent quantity or decreasing the water content
reduced the size of primary particles in the xerogel. Using the
alcoholic solvent with low dielectric constant and polarity
caused the production of bigger primary particles;however, this
effects can be minimized by introducing the reaction of
transesterification. Heating the specimens up to 600℃ caused
TiO2 to crystallize; silicate gel, even heating up to 1200℃,
still maintained at its non-crystalline form. Elemental
mapping and FT-IRresults showed that using the sol-gel
process can mix SiO2 and TiO2 atatomic/molecular scales
and a homogeneous solid mixture so can be obtained.Mixing
TiO2 and SiO2 at atomic scale causes TiO2 to maintain it
anatasestructure at temperatures up to 1200 ℃.
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