Two-step synthesis of niobium doped Na–Ca–(Mg)–P–Si–O glasses

Abstract Niobium doped biosolubility glasses in the Na–Ca–(Mg)–P–Si–O system were prepared by using an untypical two-step synthesis route. The parent glass was melted air atmosphere at 1350 °C followed re-melting Nb crucible with addition of metallic Mg/Ca powder nitrogen atmosphere. second melting step carried out 1450–1650 °C, induction furnace. topography and structure obtained characterized confocal microscopy, X-ray diffraction infrared spectroscopic techniques. chemical compositions examined energy-dispersive spectroscopy (EDS). found to be grayish color, amorphous having network connectivity between ~ 2.5 2.7. re-melted lower than one glass. consists a highly disrupted silicate predominantly Q 2 groups as well isolated orthophosphate tetrahedra. contains nanocrystallites consisted apatitic PO 4 3? groups. contain non-apatitic or calcium phosphates. transition temperatures range from 530 568 exhibit higher values for glassed Ca metal. These have improved thermal stability compared reference bioglasses. test phosphate buffered saline solution (PBS) confirms that properties HAp formation on surfaces observed.