Preparation and studies on surface modifications of calcium-silico-phosphate ferrimagnetic glass-ceramics in simulated body fluid

摘要

The structure and magnetic behaviour of 34SiO_2-(45 -x) CaO-16P_2O_5-4.5 MgO-0.5 CaF_2 -x Fe_2O_3 (where x = 5, 10, 15, 20 wt.%) glasses have been investigated. Ferrimagnetic glass-ceramics are prepared by melt quench followed by controlled crystallization. The surface modification and dissolution behaviour of these glass-ceramics in simulated body fluid (SBF) have also been studied. Phase formation and magnetic behaviour have been studied using XRD and SQUID magnetometer. The room temperature Mossbauer study has been done to monitor the local environment around Fe cations and valence state of Fe ions. X-ray photoelectron spectroscopy (XPS) was used to study the surface modification in glass-ceramics when immersed in simulated body fluid. Formation of bioactive layer in SBF has been ascertained using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The SBF solutions were analyzed using an absorption spectrophotometer. The magnetic measurements indicated that all these glasses possess paramagnetic character and the [Fe~(2+)/Fe~(3+)] ions ratio depends on the composition of glass and varied with Fe_2O_3 concentration in glass matrix. In glass-ceramics saturation magnetization increases with increase in amount of Fe_2O_3.The nanostructure of hematite and magnetite is formed in the glass-ceramics with 15 and 20 wt.% Fe_2O_3, which is responsible for the magnetic property of these glass-ceramics. Introduction of Fe_2O_3 induces several modifications at the glass-ceramics surface when immersed in SBF solution and thereby affecting the surface dissolution and the formation of the bioactive layer.