Influence of the Addition of Two Transition Metal Ions to Sodium Zinc Borophosphate Glasses for Optical Applications

Abstract

Effect of Co and Mo ions on the sodium zinc borophosphate glasses network was investigated. Both structural and optical properties were studied by X-ray diffraction, density, infrared spectroscopy and optical absorption. Only a broad halo is observed in the X-ray diffraction patterns indicating the non-crystalline nature of the prepared samples. Density and related parameters such as molar volume and average boron-boron separation showed that the glass network became more compact by increasing Mo oxide. Fourier Transform Infrared (FTIR) spectroscopy results showed that the free Co - Mo sample revealed the formation of structural building units of the borate and phosphate glasses. The addition of Co and Mo oxides cause variation in structural sites of the glass formers which appear as a small change in the FTIR spectra. The Structural results showed that the small amount of Co and Mo cause a minor irregular change in the structural units of borophosphate glasses. The optical absorption spectra in UV-Visible regions were used to study optical d-d transitions of Co and Mo ions. No absorption bands were observed for the Co free with 1mol% Mo sample. This is indicating that the observed bands in the optical spectra are due to Co ions only. Analysis of the absorption spectra showed that the Co ions occupy both octahedral and tetrahedral sites. The calculated optical energy gap, Urbach energy and refractive index of all the prepared samples were found to be glass composition dependent.