The structure of solids is described at atomic scale by a set of stereo-chemical characteristics such as: internuclear distances, angles between connection orbital, coordination numbers, but also by the type and the intensity of the physical and chemical interactions between the component ions.
It is important from the knowledge of the structural particularities point of view the evaluation of the fragile / strong character of glasses at temperatures T ≥ Tg.
This paper proposes a measure – called the fragility percentage pF – that estimates as percentage the fragile feature of a glass forming melt.
The fragility percentage pF in the case of glasses having T ³ T g defined in a range spanning from strong systems (pF = 0%) to ideal fragile (pF = 100%) were considered and an application for some silicate glasses SiO2, Na2O . 2SiO2, 44 Na2O . 56SiO2 şi Na2O . SiO2 were presented.