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Melt-quenching method was employed for obtaining a glass-ceramic with the following composition 42P(2)O(5). 40CaO.5SrO.10Na(2)O.3TiO(2) (mol%) glass. The crystallization and sintering behavior of glass have been studied by using DTA, HSM, XRD, FTIR and SEM methods. It was determined that the surface and volume crystallization mechanisms act simultaneously in bulk glass samples. The comparison of DTA and HSM data revealed that the sintering and crystallization processes are independent. The sintered calcium phosphate glass ceramic which contained bioactive beta-Ca-3(PO4)(2) and beta-Ca2P2O7 phases was successfully prepared. It was determined that during crystallization the primary phase in the precipitate was beta-Ca(PO3)(2). Other phases appearing in the resulting glass-ceramic were: alpha-Ca2P2O7, gamma-Ca2PO7, Ca4P6O19 and CaHPO4(H2O)(2). Crystalline phases containing Sr and Ti were not detected. SEM analysis of the glass-ceramic microstructure revealed surface crystallization of glass particles and plate-like morphology of crystal growth. The result of the in vitro bioactivity showed that no apatite layer was formed on the surface of the as-prepared glass-ceramic samples after immersion in the simulated body fluid (SBF).

Glasses with a constant B2O3 and an increasing La2O3 content in the system La2O3-SrO-B2O3 were obtained by the usual melt quenching procedure. The crystallization and sinterability of the glasses were investigated by hot stage microscopy (HSM), differential thermal analysis (DTA), X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). XRD analysis of the bulk samples evidenced the formation of the crystalline phases: La2SrB10O19, SrB6O10 and SrLaBO4. XRD and TEM/SAED analyses showed a polymorphic crystallization of the glass sample containing 14.3 mol% La2O3 with precipitation of the La2SrB10O19 phase. SEM analysis confirmed the surface crystallization mechanism of this sample. The kinetics of crystallization of the same sample was examined by DTA and the activation energy of crystal growth was calculated by the Kissinger model to be E-a=458 +/- 63 kJ mol(-1).