Recebido em 2/12/96; aceito em 18/2/97 We describe the preparation and some optical properties of high refractive index TeO 2 -PbO-TiO 2 glass system. Highly homogeneous glasses were obtained by agitating the mixture during the melting process in an alumina crucible. The characterization was done by X-ray diffraction, Raman scattering, light absorption and linear refractive index measurements. The results show a change in the glass structure as the PbO content increases: the TeO 4 trigonal

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... amids characteristics of TeO 2 glasses transform into TeO 3 trigonal pyramids. However, the measured refractive indices are almost independent of the glass composition. We show that third-order nonlinear optical susceptibilities calculated from the measured refractive indices using Lines' theoretical model are also independent of the glass composition.