Vol. 31, Issue 1, pp. 223-229 (2001)

Abstract

The optical properties of doped sol-gel derived materials were studied. Two types of materials were examined; thin films doped with titanium dioxide and bulks doped with pH indicators: Bromothymol Blue and Nile Red. Different amounts of TiO₂ (in concentrations: 20, 40, 60 and 80 mol%) were entrapped into the silica sol-gel thin films. The refractive indices of the films were measured. A linear increase of refractive index with increasing addition of TiO₂ was observed. Bromothymol Blue and Nile Red pH indicators were entrapped into the sol-gel bulks. Two methods of dye immobilization were used. In the first method, indicators were mixed with liquid hydrolyzate used for bulk preparation. In the second one, the dried sol-gel bulks were impregnated with liquid dye solutions. The absorption spectra in the visible range were examined for dyes in solutions and sol-gel bulks. Changes in absorption spectra were observed depending on the way of dopant entrapment.