Properties and structural features of iron doped BABAL glasses

• Main Authors: Reis Signo Tadeu dos, Pontuschka Walter M., Yang Jinbo B., Faria Dalva L A.
• Format: Article
• Language: English
• Published: Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol) 2003-01-01
• Series: Materials Research
• Subjects: aluminoborate glass; structure; chemical durability
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392003000300013

The chemical durability, density and structure of the BABAL glasses with batch compositions (100-x)(0.30BaO·0.50B2O3·0.20Al2O3)·xFe 2O3 (1 < x < 10 mol%), were investigated using Mössbauer spectroscopy, electron paramagnetic resonance (EPR), X-ray diffraction, Raman and differential thermal analysis (DTA). The chemical durability for the glass of composition 27BaO·45B2O3·18Al 2O3·10Fe2O3 (mol%) at 90 °C in distilled water was 700 times lower than that of iron phosphate glass 40Fe2O3·60P2O 5 (mol%). The Mössbauer spectra indicate the presence of iron (II) and iron (III) in tetrahedral or octahedral coordination. The results obtained from the g ef = 4.3 EPR line are typical of the occurrence of iron (III) occupying substitutional sites and the line g ef = 2.0 is related to 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 paths of X-ray diffraction are typical for glasses based in borate glasses. The Raman spectra showed that the boroxol ring disappears with the increase of iron content, concomitant with the appearance of BO4 and tetraborate structural units. At these conditions, an increase of dissolution rate and clustering of iron ions is observed.