Influence of Fe cations on the structural and optical properties of alkali-alkaline borate glasses

Abstract

To explore the impact of iron oxide (Fe2O3) on the structure and optical features of some borate glasses. A glass system with the formulation [(10.5 CaO+ 16.5 Na2O+ (73-x) B2O3+ x Fe2O3), where x = 0, 1, 2.5, 5 and 10.5 mol. %] was prepared using the melt-quench technique. The structure of obtained glasses were characterized and the physical parameters such as density, molar volume, atomic packing factor and bond length were calculated. The optical absorption spectra of the glasses were recorded in the wavelength range 190–1100 nm. Absorption bands observed around 450-550 nm in absorption spectra is due to the d-d transition of 6A1g(S) → 4T2g(G) which indicates the presence of iron ion in trivalent state (Fe3+) with distorted octahedral symmetry. The amorphous nature was confirmed by comparing the experimental and empirical density values. Moreover, these values of the experimental and empirical density were employed to expect the crystallization that occur at x= 37.2 mol % of Fe2O3. The obtained results show a decrement in the chemical bond energy, and bond force constant with Fe2O3 increasing. The expermental density and molar volume show an increasing behaviour with Fe2O3 increment.