Systematic assessment of the compositional dominance over physico-chemical properties in the SiO2-Al2O3-B2O3 based glassy networks
Branislav Hruška, Roman Svoboda, Aleksandra Nowicka, Jaroslava Michálková, Beáta Pecušová, Jakub Michalík, Mária Chromčíková
Abstract
• Density, refractive index, and molar refractivity are linearly additive combinations of the roughly equally weighted contributions of the three network-forming oxides (SiO 2 , Al 2 O 3 , and B 2 O 3 ). Modifying oxides (Na 2 O, K 2 O, CaO, BaO, and ZnO) have a minimal impact on these properties. • Thermo-mechanical properties are primarily determined by Al 2 O 3 content, with limited influence from SiO 2 and B 2 O 3 . During the glass transition, a notable discrepancy between volume and enthalpy behavior was observed. • B 2 O 3 addition significantly influences viscosity characteristics, including activation energy of viscous flow and kinetic fragility. Series of seven aluminoborosilicate glasses was studied by means of thermo-analytical and spectroscopic methods to identify the influence of the individual network-forming oxides (SiO 2 , Al 2 O 3 and B 2 O 3 ) on the particular classes of measured properties. The compositional correlation of the observed trends was enumerated by means of multilinear regression analysis. The base physico-chemical properties, such as density, refractive index and molar refractivity, were found to be a linearly additive combination of the roughly equally weighted contributions of the three network-forming oxides. The thermo-mechanical properties, i.e., the glass transition temperature (determined from volume, enthalpy and viscosity measurements) as well as coefficients of thermal expansion, were dominantly determined by the Al 2 O 3 content. On the other hand, the internal properties of the viscous flow measured in the 10 7 – 10 11 Pa·s range, i.e., the activation energy of viscous flow and kinetic fragility (defined under the Angell's concept) were driven by the B 2 O 3 content.