Influence of Ga3+ ions on the structure and in vitro bioactivity of B2O3–SiO2–Na2O–CaO glass system

Abstract

Bioactive borate glasses were doped with Ga2O3 in order to improve their biological properties. The samples were synthesized by melt quenching technique and characterized by X-ray diffraction, UV–vis spectroscopy and FTIR techniques. The physical parameters such as density, molar volume, O2 molar volume, O2 packing density and excess molar volume and Ga ion concentration were also evaluated. The data obtained indicated that high density sample shows negative excess volume which exhibits more compactness with low porosity than other glasses. Further, the sample with low content of Ga2O3 with high value of Ve along with high O2 molar volume VO shows high dissolution rate exhibits higher bioactivity. The bioactivity of these glasses was studied in vitro in SBF solution. The post-soaked samples were analyzed using XRD, SEM and MIR. From the quantitative analysis of the spectroscopic data of both pre–immersed and post–immersed samples together with the information on variation of pH value of residual solution as a function of immersion time, it is concluded that the participation of gallium ions in tetrahedral positions is obstruction for rate of formation of HA layer and for the bioactivity of the samples.