Structure-topology-property correlations of sodium phosphosilicate glasses

Abstract

In this work, we investigate the correlations among structure, topology, and properties in a series of sodium phosphosilicate glasses with [SiO2]/[SiO2 + P2O5] ranging from 0 to 1. The network structure is characterized by (29)Si and (31)P magic-angle spinning nuclear magnetic resonance and Raman spectroscopy. The results show the formation of six-fold coordinated silicon species in phosphorous-rich glasses. Based on the structural data, we propose a formation mechanism of the six-fold coordinated silicon, which is used to develop a quantitative structural model for predicting the speciation of the network forming units as a function of chemical composition. The structural model is then used to establish a temperature-dependent constraint description of phosphosilicate glass topology that enables prediction of glass transition temperature, liquid fragility, and indentation hardness. The topological constraint model provides insight into structural origin of the mixed network former effect in phosphosilicate glasses.

High Glass Transition Temperature Barium Silicophosphate Glasses Designed with Topological Constraint Theory

“…With a increasing content of SiO 2 , the silicon atoms of glasses are consisted of both Si (6) octahedral units and Si (4) tetrahedral units. In this case, the number of Si (6) could be readily calculated with the ratio, ½P2O5À½BaO 4 , which is agreed with what Jiang et al 20 and Hermansen et al 19 reported. We consider the number of Si (6) units in barium silicophosphate glasses obeys the following rule: Figure 2 shows the deviation between the measured content of Si (6) (multiplying the fraction of Si (6) and the content of SiO 2 ) and calculated content of Si (6) in 20BaO-xSiO 2 -(80-x)P 2 O 5 glasses.…”

“…Figure 1(a) reveals that as the content of silicon oxide increases, the peaks of Si (4) (~À123 ppm) and P (3) (~À38 ppm) are enhanced, while the peaks of Si (6) (~À220 ppm) and P (2) (~À27 ppm) become weaker(X (n) represents the network former ion X associated with the number n of bridging oxygen atoms). 16,18,19 Network former units (NFUs) of Si (4) , P (2) , and P (3) possess a tetrahedral structure, while the NFU of Si (6) has an octahedral structure, which is unique in barium silicophosphate glasses. The fraction of each NFU is shown quantitatively in Fig.…”

Toward hard and highly crack resistant magnesium aluminosilicate glasses and transparent glass‐ceramics

“…Based on the excellent agreement between the modeled and measured hardness values for series of glasses, such as soda lime borate glasses, topological constraint theory has proven to be a powerful tool to allow predicting hardness values of series of glasses with respect to composition . However, when predicting glass hardness with topological constraint theory for series of borosilicate, phosphosilicate, and aluminosilicate glasses, the aforementioned model observed a less accurate relationship between the number of rigid constraints and glass hardness . Through changing the counting approach, that is, using density of topological constraints instead of number of constraints per atom, further understanding about predicting the glass hardness according to the topological constraint theory points out that glass hardness is governed by the density of rigid constraints under an indenter, rather than by the number of rigid constraints per atom …”

Structural and topological aspects of borophosphate glasses and their relation to physical properties

“…Temperature dependent constraint theory has been applied to borates [44][45][46] and phosa) Electronic mail: yy@bio.aau.dk phates, 47,48 as well as borosilicates 49 and phosphosilicates 50 which also exhibit a MNFE. The structure-property relations of sodium borophosphate glasses have been modeled with temperature dependent constraint theory by Jiang et al 51 They achieved some promising results, yet their model is not predictive since the experimental T g of the entire xNa 2 O(1 − x)P 2 O 5 and xNa 2 O(1 − x)[0.4B 2 O 3 0.6P 2 O 5 ] pseudobinary systems are used to scale their modeled T g .…”