Properties and structural features of iron doped BABAL glasses

The chemical durability, density and structure of BABAL glasses with batch compositions (100-x)(0.30BaO.0.50B2O3.0.20Al2O3).xFe2O3 (x = 1-10 mol%), were investigated using Mossbauer spectroscopy, EPR, XRD, Raman analysis and DTA. The chemical durability for glass of composition 27BaO.45B2O3.18Al2O3.10Fe2O3 (mol%) at 90 C in distilled water was 700 times lower than that of iron phosphate glass 40Fe2O3.60P2O5 (mol%). The Mossbauer spectra indicated the presence of iron (II) and iron (III) in tetrahedral or octahedral coordination. The EPR results were typical of the occurrence of iron (III) occupying substitutional sites and the association of two or more Fe ions found in the interstices (or holes occupied by the glass modifier cations) of the glass network. The XRD was typical for glasses based on borate glasses. The Raman spectra showed that the boroxol ring disappeared with the increase of iron content, concomitant with the appearance of BO4 and tetraborate structural units. Under these conditions, an increase of dissolution rate and clustering of iron ions were observed. 25 refs.