| The structural, magnetic and microstructural properties of ferrimagnetic bioglass ceramics (FBC) in the system {lcub}0.45(CaO,P2O5) · (0.52-x)SiO2 · xFe 2O3 · 0.03Na2O{rcub} with x = 0.05, 0.10, 0.15, 0.20 were studied as a function of composition and heat-treatment temperature. Specimens from each samples series were heattreated at temperatures in the range 600–1000°C.; X-ray powder diffraction and Rietveld refinement methods, magnetic measurements and scanning electron microscopy with energy dispersive x-ray spectroscopy were used in our studies.; Calcium phosphate [Ca3PO4)2], which is the biocompatible component of the materials, and magnetite Fe3O 4 are the two major crystalline phases that were developed in all samples series. In the two series of samples with x = 0.15 and 0.20, calcium phosphate undergoes a gradual transition from the monoclinic to the rhombohedral crystal system (Space Group P21/a, R3c) as the heat-treatment temperature increases from 800 to 1100°C. It crystallizes only in R3c in the samples series with x = 0.05 and x = 0.10. Magnetite crystallizes in the orthorhombic system (SG Imma) in weight fractions determined by the heat-treatment temperature. In the system with x = 0.20, magnetite partially converts to hematite (SG R3c) in weight fractions that increase with the heat-treatment temperature.; The saturation magnetization of all specimens depends on the starting composition in Fe2O3 while it becomes maximum in samples that were heat-treated at 800°C in all sample series. Magnetization loops show that the energy stored in the material is greatly affected by composition and heat-treatment, but not in a systematic way.; SEM and EDX spectra reveal a variety of microstructures that are determined by the processing parameters of each sample. Dendrite structures consisting of Fe and O with crystallites of various sizes form on a glassy matrix of P, Si, Ca and O in the samples series 20G, while very fine surface microstructures are observed in the series 15G. |
