Effect of lithium doping on the glass transition behavior of the Bioglass 45S5.

Differential scanning calorimetry, thermomechanical analysis and Raman spectroscopy were used to study the role of the Li 2 O and P 2 O 5 oxides on the structural relaxation phenomena in the Li-doped 45S5 Bioglass. The glass transition behavior was found to be similar for the enthalpy and volume manifestations of the relaxation motions. The Tool-Narayanaswamy-Moynihan (TNM) model was applied. An improved simulation-comparative methodology was used to determine the model relaxation parameters. The TNM model parameters and the selected glass transition characteristics (the glass transition temperature and the coefficients of thermal expansion) showed no statistically significant correlation with the particular elements present in the synthesized glasses. Hence, the information about the glasses composition was used to calculate the theoretical amounts of the Qn Si species in the Li-doped 45S5 glasses. It was found that practically all explored physico-chemical quantities related to the glass transition kinetics show a correlation with the content of Q2 Si species that are responsible for the formation of the chain-like structures in the present glasses. [ABSTRACT FROM AUTHOR]