Fe2O3 within Na2O–Al2O3– B2O3 glasses to study the structural and optical features changes

Abstract

This paper aims to study the structural and optical properties of the glass system 75B2O3 + 5Al2O3 + (20-x)Na2O + (x)Fe2O3; (x = 0, 1, 3 and 5 mol. %). The melt quenching approach was utilized to prepare all the glass samples. The Fourier transform infrared (FTIR) results confirmed the back conversion of the BO4 units into BO3 units with a steady increase in nonbridging oxygen content. The absorbance of all the samples was determined in wavelength range (300–650 nm). The overlap between the real absorption edge and an absorption band at about 370 nm produces a pseudo absorption edge accompanied by an error in calculating the optical band gap. To overcome this error, a deconvolution process is performed. The bands from 417 to 469 nm confirm the presence of trivalent iron cations (Fe3+) within the glass matrix. These Fe3+ cations have a distorted octahedral symmetry originating from d-d transitions. The densities (ρemp and ρexp), molar volume (Vm) optical band gap (EOpt), refractive index (n0) and nonlinear refractive index (n2) were determined. The ρemp, ρexp,Vm, n0 and n2 of the prepared glasses show an increasing behavior, with further Fe2O3 doping, while EOpt shows a decreasing one. Further, the addition of Fe2O3 produced an increment in Racah parameters (B and C) values, which in turn reflects the more stability of the bonds between Fe cations and their complexes.