Effect of Strontium Substitution on the Structure of 45S5 Bioglasses

Abstract

Strontium substitution has been found to have a beneficial effect on tissue growth in traditional bioglasses. In this paper, we have studied the effect of SrO/CaO substitution on the structure of 45S5 bioglasses in the series of 46.1SiO 2 3 24.4Na 2 O 3 (26.9Àx)CaO 3 2.6P 2 O 5 3 xSrO (x = 0, 1, 5, 10, 15) compositions using molecular dynamics (MD) simulations with effective partial charge potentials and a combination of constant temperature and pressure (NPT) and microcanomical (NVE) ensembles. The calculated neutron structure factor and neutron broadened total correlation function of the 45S5 glass were compared with experimental diffraction data and the two were found to be in reasonable agreement with each other. The SrO/ CaO substitution effects on cation local environments were analyzed by studying the partial pair distribution functions, bond angle distributions, coordination number and its distribution. Change of the medium-range structures were characterized by Q n distributions and network connectivity, cationÀcation distributions and their aggregation, as well as the preference of modifiers around the glass former cations. It was found that strontium substitution leads to a linear increase of both molar volume and density. The SrÀO bond distance is found to be around 2.59 Å, and the average strontium coordination number is around 7.0 in the substitution series. The glass network structures such as Q n distribution and network connectivity does not change much with SrO/CaO substitution. Calcium and strontium ions were found to preferentially distribute around phosphorus ions. These structural and property changes were correlated to observed glass dissolution behavior and bioactivity of strontium-containing bioactive glasses.

Effect of strontium inclusion on the bioactivity of phosphate-based glasses

“…The Sr-O coordination number was between four and five in the borosilicate glass, in contradiction to our results, but it was between seven and eight for the tin silicate glass and around seven in other computational studies [13,14].…”

“…Molecular dynamics (MD) simulations provide the atomic structure of the glass, as well as enabling computation of large-scale materials properties. We and others have previously used MD simulations to elucidate the connection between atomic structure and dissolution behaviour of a variety of silicate [20][21][22][23][24][25][26][27] and phosphate glasses [28][29][30] intended for implantation, including strontium-containing silicate glass [13,14]. However, there have been no simulations of Sr in phosphate glass.…”

“…It is therefore vital to derive a potential that is as accurate as possible. Previous simulations of Sr-containing silicate glasses [13,14] have used a rigid-ion interatomic potential, in which the ions have partial charges and the polarizability of the ions is not included. Although this can often give satisfactory agreement with experimental data [22], it has been shown [31] that using a potential which incorporates the polarizability of the oxygen atoms, typically using the shell model, provides a more accurate representation of the medium-range structure of glasses, particularly the network connectivity and Q n distribution.…”

Structural Characterization of FeO–SiO₂–V₂O₃ Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

“…A wide distribution of the Si-O-Si angle from ~120° to 180° is consistent with the reported results. 38,39) According to previous studies, 43,48) the introduction of a modifier will cause the decrease of the Si-O-Si angle in the silicate network. The average angle of the Si-O-Si, listed in Table 5, slightly decreases from ~155° to 151° with increasing the V 2 O 3 content, this may be an indication that V 2 O 3 act as a modifier in this tetrahedral network.…”

Structural role of ZrO2 and its impact on properties of boroaluminosilicate nuclear waste glasses

“…25 Many studies have been systematically conducted and revealed shortrange and medium-range structural features utilizing MD simulation in various glass systems such as sodium silicate glasses, 26 aluminosilicate glasses, 27 lithium disilicate glasses, 28 cerium aliminophosphate glasses, 29 europium-doped silicate glasses, 30,31 erbium-doped sodium silicate glasses, 32 lithium vanadophosphate glasses, 33 and bioactive glasses. [34][35][36] However, MD simulation of nuclear waste glasses has been limited due to the lack of pairwise potential sets for boron. With the recent development of modified composition-dependent pairwise potential sets, it is now possible to simulate complex glass compositions.…”