Interplay between non-bridging oxygen, triclusters, and fivefold Al coordination in low silica content calcium aluminosilicate melts

In the present work the structural properties of low silica content calcium aluminosilicate melts with concentration ratio CaO/Al2O3 = 1 are investigated in the liquid and undercooled states by neutron diffraction experiments and ab initio molecular dynamics simulations. The results show the presence of AlO5 units and triclusters as well as non-bridging oxygen in the fully charge balanced compositions. Moreover, our findings allow us to identify a possible interplay between these structural units. Finally, we discuss the influence of these defective structural units on the properties of tetrahedral network and more particularly their implication on the evolution of the viscosity and the fragility. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4766920]