Ion Releasing Abilities of Phosphate Invert Glasses Containing MgO, CaO or SrO in Tris Buffer Solution

CaO-TiO2-P2O5-Na2O invert glasses developed in our group showed bioactivity and good sinterability. In the present work, phosphate invert glasses, in which CaO was substituted with MgO or SrO (PIG-MO, M = Mg, Ca, Sr), were prepared and their ion-releasing behaviors were evaluated. Glass transition temperature (Tg) and crystallization temperature (Tc) were estimated from differential thermal analysis. (Tc – Tg)/Tg value, which indicates glassification of the glass, of PIG-MgO was higher in comparison with those of the other glasses. Laser Raman spectroscopic analysis indicated that peaks due to P2O7 4– group in the spectrum of PIG-MgO were smaller than those in the spectra of PIG-CaO and PIG-SrO. The structure of PO4 3–-M2+PO4 3– was expected to form easily, resulting in the good glassification of PIG-MgO. The ion amounts dissolved from PIG-MgO containing a large amount of PO4 3– group were 2 ∼ 3 times larger than those of the other glasses.