The Influence of Cu2+ and Mn2+ Ions on the Structure and Crystallization of Diopside-Calcium Pyrophosphate Bioglasses

Abstract

The influence of two divalent cations, Cu2+ and Mn2+, on the structure, sintering, and crystallization of glasses and glass-ceramics in the diopside-calcium pyrophosphate system (90 wt.% diopside (CaMgSi2O6), 10 wt.% calcium pyrophosphate (Ca2P2O7)) was investigated. Glasses with 1, 3, and 5 wt% MnO or CuO additives were prepared by melt-quenching and characterized by XRD, Si-29 and P-31 NMR, DTA, and FTIR This revealed that the silicate network is predominantly coordinated in Q(2) (Si) units for all glasses, while phosphorus tends to inhabit an orthophosphate (Q(0)) environment. All glasses had a high rate of bioactivity after immersion in simulated body fluid. A slight depolymerization was observed in the doped glasses leading to lower T-g values in comparison with the parent glass. All glass-ceramics exhibited the formation of diopside as the primary crystalline phase after sintering at 850 degrees C/1 h. In comparison with the parent glass, the doped glasses featured significantly larger processing windows (T = T-c-T-g), ensuring good sinterability. Further, with increasing doping levels, the glasses exhibited a gradual decrease in T-p and T, suggesting an increased tendency toward devitrification. All Cu- and Mn-containing glasses exhibited the formation of hydroxyapatite, making them good candidates for biomedical applications and tissue engineering.