Thermal and structural studies of Li2O-Na2O-SrO-TiO2-B2O3-P2O5 glasses by DTA, IR and EPR spectroscopy

H. Bih, H. Sinouh, H. Es-soufi, L. Bih, M. Haddad, L. Bejjit, B. Manoun, P. Lazor

Abstract


Glasses in the system 33.33[xNa2O-(1-x)Li2O]-2.5SrO-2.5TiO2-45B2O3-16.67P2O5 (0.0 ≤ x ≤ 1.0) were prepared by standard melt quenching procedures, and their physical properties were characterized by thermal analysis, density measurements. Their local structures were comprehensively characterized by Infrared spectroscopy (IR) and electron paramagnetic resonance (EPR). The variation of the glass transition temperature as a function of the glass compositions is non-linear. The infrared spectroscopy of the glasses has identified the presence of different structural grouping units in the glassy-matrix. It is found that the stretching and bending vibration modes of borate groups are more sensitive to the substitution of alkali elements. EPR experiments have shown the presence of Ti3+ centres in the glasses. The variation of the g-factor as a function of the Na/(Na+Li) ratio presents a minimum around (x=0.5). The composition non-linearity behavior of Tg, vibration bending mode, and g-factor are signature of the mixed alkali effect in the glasses.

Keywords


borophosphate glasses; thermal analysis; IR; EPR; mixed alkali effect (MAE)

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