The macroscopic and high temperature properties of lithium borophosphate glasses were determined in this contribution. Our data, obtained on 50LiO-xBO-(50-x)PO glasses, confirm a continuous and linear increase of the glass transition temperature with the B/P substitution but show a two-domain evolution of the kinetic fragility with a steep decrease in the low BO region (0 ≤ x ≤ 10) followed by a moderate increase for higher BO contents. In order to understand this different behaviour, the glass structure was investigated in detail using 1D and 2D B/P correlation solid state nuclear magnetic resonance. The local and medium orders of borate units were determined by 1D MAS-NMR, 2D B DQSQ- andB(P) D-HMQC NMR experiments. The latter NMR technique was also used to deeply interpret the 1D P MAS-NMR spectra. Altogether the data allow (i) highlighting of the presence of four borate and seven phosphate units, (ii) evaluation of the number of homopolar POP and mixed POB linkages, and (iii) contribute to a better understanding of the T and kinetic fragility evolution.
New bioactive phosphate glasses suitable for continuous fibre production are investigated in this work. The structure of both bulk and fibres from Na 2 O-CaO-MgO-P 2 O 5 glasses has been studied by means of Raman and 31 P and 23 Na 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, whilst the dissolution rates are governed by the Q i speciation of the PO 4 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 PO 4 units throughout the glass network and, therefore, causes a reduction in the kinetic fragility.
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