Study the effect of alkali/alkaline earth addition on the environment of borochromate glasses by means of spectroscopic analysis

Glassy samples of composition xSrO-(30 - x)Li2O-65.5B(2)O(3)-0.5Cr(2)O(3) (x = 0, 5, 10, 15 and 20 mol%) were fabricated by using the melt quenching technique method. The investigated glass samples have been examined using powder X-ray diffraction (XRD) technique. FT-IR spectroscopy, density, optical absorption in UV-VIS range and the calculated optical basicity and EPR spectra were recorded. The obtained results of the XRD spectra of all the samples confirmed the amorphous nature of the prepared glasses. The spectrum of FT-IR reveals that, the BO4 units decrease with increasing SrO content and the non bridging oxygen's increase. The obtained density and the molar volume exhibit linear increase with increasing SrO content. Optical measurements show a decrement of optical band gap energy and steepness parameter as well as an increment of the Urbach energy and refractive index. The ligand field parameters calculation shows that, the values of the crystal field strength and the degree of covalency between ions increase as well as the interelectronic d-d repulsion Racah parameters decrease. The increase of the (Dq/B) ratio with increasing SrO content which reaches to 2.58 for x = 20 mol%, suggesting that strong crystal field strength. An increase of the electronegativity by replacing Li2O by SrO, causes a decrease of the glass matrix basicity. The obtained EPR parameters indicate that the increasing of Cr3+ signal intensity and spin density. The analysis of the results indicated that, the chromium ions are present in trivalent covalent in the octahedral coordination are more predominate. (C) 2013 Elsevier B. V. All rights reserved.