Structural investigations on P2O5-CaO-Na2O-K2O: SrO bioactive glass ceramics

In the present work, glasses of a particular composition (60-x) P2O5-20CaO-17Na2O-3K2O: xSrO (0.5≤x≤1.5) mol% were synthesized using conventional melt quenching technique. Further, samples were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analyses (DTA) techniques and Fourier Transform Infrared (FT-IR) spectra. In vitro bioactivity was evaluated by soaking glass ceramic powders in SBF solution for 7 and 15 days. XRD patterns of glass ceramics have clearly confirmed the formation of various crystalline phases K2Sr(PO3)4, α-Ca2P2O7, Ca2Sr(PO4)2, Ca5(PO4)3(OH) and Ca3(PO4)2. Random spreading of uneven sized micro crystals with distinct boundaries in the glass matrix have been observed from SEM pictures. DTA scans revealed an increase in the content of SrO with heating rate causes the glass transition (Tg) and crystallization temperatures (Tc) towards lower side, that confirms the decrease in rigidity of glass network. FT-IR spectra showed that there is an increase in the degree of structural disorder and the formation of a crystalline hydroxyapatite layer with soaking time. From the analyses of all the above results, it can be concluded that the sample doped with 1.5 mol% of strontium is found to exhibit high bioactivity.