Novel calcium phosphate ceramics prepared by powder sintering and crystallization of glasses in the pyrophosphate region

Silica-free phosphate glasses containing small amounts of Na₂O and TiO₂ with the composition of Ca/P = 1 in atomic ratio were obtained. When powder compacts of the glasses were heated at 850 °C, they crystallized and subsequently sintered, resulting in glass-ceramics containing β–Ca₃(PO₄)₂ and β–Ca₂P₂O₇ crystalline phases. The glass-ceramics show a relatively high fracture toughness of KI_C ≈ 2 MPa m^0.5. By soaking in simulated body fluid at 37 °C, a calcium phosphate phase was formed newly on the surface of the glass-ceramics.