Apatite-forming ability and magnetic properties of glass-ceramics containing zinc ferrite and calcium sodium phosphate phases

摘要

Fine particles of zinc ferrite (ZnFe_2O_4) and calcium sodium phosphate [NaCaPO_4] were crystallized in bulk x (ZnO, Fe_2O_3)(65-x)SiO_220(CaO, P_20_5)15Na_2O (6≤x≤21 mol %) glassy matrix by heat treatment. Initial magnetization curves reveal that samples with x = 6 and 9 mol % zinc-iron oxide exhibit both ferrimagnetic and paramagnetic contributions, whereas, samples with x>9 mol % zinc-iron oxide exhibit only ferrimagnetic contribution. This observation is supported by the disappearance of the electron paramagnetic resonance (EPR) absorption line centered at g≈4.3 in samples with x>9mol % zinc-iron oxide. Apatite-forming ability of the glass-ceramic samples was investigated by examining apatite formation on the surface of the samples treated in simulated body fluid (SBF). Increase in apatite-forming ability was observed with an increase in zinc-iron oxide content. The results obtained have been used to understand the evolution of the apatite surface layer as a function of immersion time in SBF and glass-ceramic composition. A good correlation has also been observed between the magnetic nature of the samples and their apatite-forming ability. These materials are expected to find application as thermo-seeds in hyperthermia treatment of bone cancer.