Preparation and characterisation of high refractive index PbO–TiO2–TeO2 glass systems

Abstract

We describe the preparation and characterisation of high refractive index PbO–TiO₂–TeO₂ glass systems. Highly homogeneous glasses were obtained by agitating the oxide mixture during the melting process in an alumina crucible. The characterisation was performed by X-ray diffraction, density, dilatometry, Raman scattering, light absorption and linear refractive index measurements. The results show a change in the glass structure as the PbO content increases: the TeO₄ trigonal bipyramids characteristic of TeO₂ glasses transform into TeO₃ trigonal pyramids. However, the measured refractive indices are almost independent of the glass composition. We show that third-order non-linear optical susceptibilities calculated from the measured refractive indices using Lines' theoretical model are also independent of the glass composition.