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Abstract: A homogeneous crack-free nano- or meso-porous silica films on silicon was fabricated by colloidal silica sol derived by hydrolyzing tetraethyl orthosilicate (TEOS) catalyzing with (C₄H₉)4N⁺OH^- in water medium. the solution with ratio of H₂O/TEOS≥15, R₄N⁺ and glycerol as templates, combining with the hydrolyzed intermediate, controlled the silica aggregating; the templated silica film with heterostructure was developed into homogeneous nano-porous then meso-porous silica films after being annealed from 750 °C to 850 °C; the formation mechanism of the porous silica films was discussed; morphologies of the silica films were characterized. the refractive indexes of the porous silica films were 1.256-1.458, the thermal conductivity < 0.7 W/m/K. The fabricating procedure and the sequence had not been reported before.

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