Variation of Structure and Optical Material Dispersion in Lead Borate Glass Containing Multi Valence Chromium and Germanium Cations.

Abstract In pursuit of manufacturing glass having a high refractive index and low dispersion, a series of lead and borate glasses containing germanium and chromium oxide by composition 25B2O3-73.8PbO-xGeO2-(1.2-x)Cr2O3, with 0 ≤ x ≤ 1.2 mol.%, are prepared. IR measurements are carried out to explore the structure of as-prepared samples. The deconvoluted IR peaks revealed presence of bridging Oxygen up to x = 0.6 mole %. At x > 0.6 mole % none bridging Oxygen is the dominant. The dependence of the measured hydrostatic density and corresponding molar volume for the studied compositions are analyzed and discussed. The dispersion curves of refractive index (n) and absorption index (k) are calculated in the spectral range 300–2500 nm. The effect of increasing the ratio GeO2/ [GeO2 + Cr2O3] on the calculated dispersion energy, lattice energy, oscillator energy and material dispersion are deduced. For photonic applications, the wavelength at zero material dispersion for the investigated samples is calculated and compared with other systems based on Borates, silicates and Germinate fiber. The results recommend that the present glass could be used in different modern optoelectronics devices.