Glass transition effect in liquation silicate–borate–phosphate glasses

Abstract

Glass transformation effect of liquation glasses from the SiO 2-B 2 O 3-P 2 O 5-K 2 O-MgO-CaO system was studied by DSC, SEM-EDS and 31 P, 29 Si and 11 B MAS NMR spectroscopy methods. The relation between the B 2 O 3 content in the analysed glasses and phase separation phenomenon, structure and glass transition effects was discussed. It was shown that increasing content of B 2 O 3 causes the formation of P-O-B III , P-O-B IV and Si-O-B III and Si-O-B IV bonds which results in the appearance of liquation in analysed glasses. Simultaneously, double glass transition effect was observed with gradual decrease of T g and E a values. The observed relations were explained using crystalochemical parameters (i G , L) of chemical bonds present in the structure of analysed glasses.

Investigating the Crystallization Process of Boron-Bearing Silicate-Phosphate Glasses by Thermal and Spectroscopic Methods

“…It seems to the authors of the present study that this two-way behavior may signify that the thermal stability of the analyzed glasses depends, to some extent, on the transformation temperature T g and the character of the separated phases, i.e., the amorphous silicate phase and phosphate phase, formed during the liquation process. This issue is discussed in detail in [ 24 ]. The determined for the ΔT parameter may prove that the amorphous phosphate phase, in comparison with the silicate phase, is associated with higher glass stability with respect to devitrification.…”

“…First of all, for < 0.212, a single Ca 9 MgK(PO 4 ) 7 -type whitlockite phosphate was crystallized. It is worth noting that this phase was also identified in the sample that was not modified with B 2 O 3 [ 24 ]. However, when the value of ≥ 0.212 was reached, the phosphate phase Mg 3 Ca 3 (PO 4 ) 4 -type stanfieldite was a new product of crystallization in addition to the phosphate mentioned above.…”

Influence of the replacement of silica by boron trioxide on the properties of bioactive glass scaffolds

“…However, the surface of the 13‐93‐based and 13‐93‐BS BG scaffold struts is seen to be smooth (according to higher magnification images), whereas the struts of 13‐93‐B BG scaffolds appear rougher. This is a sign that the BG particles in the case of silicate 13‐88 and borosilicate (13‐93‐BS) BGs are sintered together (via a viscous flow mechanism 54 ), which results in suitable densification. In contrast, the 13‐93‐B BG particles appear to be not (completely) fused together, resulting in a greater porosity of around 95%.…”

“…The symmetry of the tetragonal BO 4 site is higher, leading to smaller quadrupolar interaction and narrower line. The 11 B line positions for BO 4 and BO 3 sites are typical for the 11 B spectra of inorganic glasses taken at the magnetic field of 7 T. 52,53 The ppm frequency scale was referenced to the 11 B resonance of 1 mol H 3 BO 3 .…”