Abstract
The understanding of atomic-scale structure is a prerequisite for establishing the physico–chemical behavior of complex glass systems. To this end, positron annihilation life time spectroscopy (PALS) is an atomic scale probe capable of investigating the subnanoscopic free volume of amorphous materials. In the present work, PALS has been used to quantify the free volume changes as a function of increasing substitution of B2O3 by Al2O3 in strontium borosilicate glasses intended to be used as sealant in solid oxide fuel cells. The free volume parameters; ortho-positronium (o-Ps) life time (τ 3) and intensity (I 3) show composition dependant variations which are correlated to the molar volume and compactness of the glasses through a commutative free volume parameter, $$~\tau _{3}^{3}{I_3}$$ . The effect of change in nanoscopic free volume induced by the substitution of B2O3 by Al2O3 on the glass transition temperature (T g), softening temperature (T s), coefficient of thermal expansion (CTE) and thermal stability of glasses have been studied. A remarkable trend-based variation in these macroscopic properties with change in free volume is observed. We envisage that the findings of this work will provide new insights in establishing subnanoscopic structure and thermo-physical property correlation of complex glass systems containing multiple network former and modifiers.
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