Structure–properties relationships in fibre drawing of bioactive phosphate glasses

New bioactive phosphate glasses suitable for continuous fibre production are investigated in this work. The structure of both bulk and fibres from Na2O–CaO–MgO–P2O5 glasses has been studied by means of Raman and 31P and 23Na nuclear magnetic resonance spectroscopies, and the structural results have been correlated with the mechanical properties of the fibres and the dissolution rate of the bulk glasses. It has been observed that the mechanical properties of the phosphate glass fibres are influenced by the glass network connectivity, while the dissolution rates are governed by the Qi speciation of the PO4 units. As seen in previous studies, molar volume seems to play an important role in the fragility behaviour of phosphate glasses. Here, a lower molar volume resulting from the increase in the oxygen packing density hinders the cooperative flow of the PO4 units throughout the glass network and, therefore, causes a reduction in the kinetic fragility

Phosphate Glasses

This chapter is dedicated to the studies on phosphate glasses, from their fundamental aspects to their most relevant applications of today. P2O5-based glasses have experienced a continuously increasing number of published works in the last decades and still they possess a bright potential. Their sometimes intricate structure has made its study a quite relevant field for the Glass Science community which attracts more and more researchers. And, on the other hand, the associated difficulties in their preparation on a large scale have led to the development of specific methods, such as those used for the melting of Nd-laser glasses. They are particularly known to have a low chemical durability, though the progress in the optimization of their composition demonstrates that can be very competitive and, in this respect, we will also pay attention to the improvement of their properties as a result of their nitridation. The structure and main physico-chemical properties of phosphate glasses will be reviewed, highlighting the most relevant and well-known applications existing nowadays, such as sealing and laser glasses, biomedical, as solid electrolytes or for the storage of wastes.F. Muñoz thanks funding from projects MAT2013-48246-C2-1-P from MINECO of Spain and I-link+0959 from CSIC. I. Ahmed would like to acknowledge the Faculty of Engineering, Advanced Materials Research Group, University of Nottingham, for provision of studentship funds