Geological Glasses

SiO2 and Al2O3 are the main constituents of Earth’s crust and mantle, where they are present together with many other oxides to form very complex multicomponent materials.

Ternary and quaternary silicate and aluminosilicate glasses are then ideal reference systems to approach the understanding of the characteristic of geological fluids of the mantle and amorphous solids in the crust.Summarily, their structure has been understood in term of interconnected (SiO4/2) and (AlO4/2)1- tetrahedra, and of non-framework cations that can locally compensate the excess of negative charge of the network which is due to the presence of (AlO4/2)1- tetrahedra and of non-bridging oxygen atoms NBOs (i.e. oxygen atoms connected to only one network former cation), which are introduced by adding network modifying oxides to the glass composition. 

The study of thermodynamics and transport properties, heat capacity of melts, silica activity and viscosity of silicate and aluminosilicate glasses and melts is an issue of great interest in the geological field, and inspired many investigations.

Physical properties of amorphous materials depend very strongly on their structure which in turn depends on their chemical composition; thus, accurate structural characterizations are a crucial step towards the full understanding of geological glass properties. One of the most efficient experimental techniques for amorphous structural characterization is Solid State Nuclear Magnetic Resonance (NMR) Spectroscopy.

Our research activity exploits Computational NMR spectroscopy to achieve accurate interpretation of experimental data and spectra, in order to finally get to an unambiguous structural characterizations of these systems.