Fragile glass - formers reveal their structural secrets

Calcium aluminates CaO - Al2O3 form a significant component of the Earth’s mantle and are an important ingredient in several materials having great utility [1]. They are, for example, an integral component of aluminous cement, the glasses have optoelectronic applications in the infra - red spectrum, and the rare - earth doped materials exhibit persistent luminescence.
Aerodynamic - levitation with laser - heating allows for the containerless processing of refractory liquid oxides and for the formation of new families of glass forming materials. Here we combine this technique with the method of isotope substitution in neutron diffraction to elucidate the structure of a single levitated droplet of the calcium aluminate CaAl2O4. The results combined with molecular dynamics simulations reveal key structural modifications on multiple length scales as the liquid forms a glass, findings that may well be applicable to other magma - related materials.