Structure and diffusion of ZnO–SrO–CaO–Na2O–SiO2 bioactive glasses: a combined high energy X-ray diffraction and molecular dynamics simulations study

Novel bioactive glasses that can release ions such as strontium and zinc provide bone growth enhancement and antibacterial properties that earlier-generation bioglasses did not possess. These glasses find applications in bone cementation, restoration and in tissue engineering. In this paper, we present combined experimental and simulation studies to explain the structure and diffusion of ZnO–SrO–CaO–Na2O–SiO2 bioactive glasses with the aim of understanding the short and medium range structure of these glasses, the structural correlation to their dissolution behaviors, and their bioactivity. High energy X-ray diffraction experiments have been performed to obtain structural information and to validate the structure models from simulations. Three glass compositions with ZnO/Na2O substitutions have been studied using molecular dynamics simulations to characterize the glass structure and calculate the ionic diffusion in these glasses. The results provide insight to local environments and structural role of zinc ions, the medium range structural features such as Qn distribution, and ionic diffusion characteristics of these bioactive glasses. The structure and ionic diffusion results are discussed in correlation to the dissolution behaviors and the bioactivity of these glasses.