Structural, thermal, morphological and dielectric investigations on 45S5 glass and glass-ceramics

Hench et al. developed in 1969 the 45S5 Bioglass® showing high biocompatibility and osteogenic ability, enabling its application in bone tissue engineering. However, the bioactivity level and other physical and chemical properties can be compromised by structural changes. It is also known that the bone growth kinetics is related to the electrical characteristics of the bioglass. This manuscript presents an extensive study on the structural characteristics of the 45S5 Bioglass® endorsing the electrical properties with the structural and morphologic changes established by controlled heat-treatments. The bioglass was synthesized by melt-quenching and the heat-treatments were made at several temperatures from 500 up to 1000 °C. XRD, Raman and FTIR spectra show the occurrence of glass crystallization for treatments above 600 °C, in agreement with the thermal analysis of the base glass. The main phase, in the glass-ceramic samples, is Na2Ca2Si3O9, presenting a secondary phase in the sample treated above 900 °C. SEM micrographs show nanosize particles in the glass-ceramics, except for the sample treated at 1000 °C, which presents submicron-size. The electrical measurements revealed that the crystal phase dominates the conduction process and the dipoles arising from the interfaces lead to relaxations phenomena.