Investigations on Selected Bioactive Glasses and Glass-Ceramics Containing Iron Oxide
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2009
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Abstract
Magnetism and magnetic materials have a strong role to play in health care and biological application such as cell separation, drug delivery and magnetic intracellular hyperthermia treatment of cancer. Magnetic bioglass ceramics (MBC) are complex and multiphase biocompatible materials, usually fabricated from the original bioglass with the addition of Fe2O3 in the basic bioglass composition. MBCs exhibit bioactivity as well as magnetic properties. This Ph. D thesis work is focussed on the preparation and characterization of CaO, MgO and ZnO based glasses containing variable amounts of iron oxide and MBC derived from them. These investigations are aimed at (i) optimization of preparative conditions of the MBC, (ii) magnetic hysteresis loss and physical property evaluation of MBC, and (iii) evaluation of biocompatibility of the MBCs by treating them with SBF. Since preparation of bioactive glasses is the first stage in the preparation of the bioglassceramics, optimization and evaluation of the properties of the base glasses are also required in order to fully comprehend the MBCs derived from them. After a careful study of the bioactive based glass containing Fe2O3 and magnetic glass-ceramics obtained by controlled crystallization of the respective parent glasses, three glass systems, viz., 41CaO(52-x)SiO24P2O5xFe2O33Na2O, (x = 0, 2, 4, 6, 8 and 10 mole %), 4.5MgO(45-x)CaO34SiO216P2O50.5CaF2x Fe2O3 (x = 0, 5, 10, 15 and 20 wt.%) and x(ZnO,Fe2O3)(65-x)SiO2 20(CaO,P2O5)15Na2O (x = 6, 9, 12, 15, 18 and 21 mole % ) with Ca/P = 1.67 and Fe/Zn = 6.5 were identified for the present investigations. Bulk glass samples belonging to the three glass systems were prepared by melt quenching technique. Powder X-ray diffraction technique was used to verify the amorphous nature of the glasses and to record the X-ray diffraction (XRD) pattern of heat treated glasses. Differential scanning calorimeter (DSC) was employed to determine the glass transition temperature (Tg) and the crystallization temperature (Tc) of the glasses. Density of the glass samples was measured using ArchimedesD principle. A microhardness tester equipped with a Vickers pyramidal indenter was used for micro hardness measurements. Electron Paramagnetic Resonance (EPR) spectra were recorded at room temperature on powder samples using a Spectrometer in the X band for understanding the valence states and local structure of iron ions as a function of composition. Magnetization versus Temperature (M-T) curves and magnetic hysteresis (M-H) loops of the samples would be obtained using a Vibrating Sample Magnetometer (VSM) to elucidate the magnetic properties of the samples. In vitro bioactivity test was performed on the samples by immersion of bulk samples in SBF (KokuboDs solution) for different periods of time and monitoring the changes in the structure of the glasses / glass-ceramics by grazing incidence XRD, reflectance FT-IR spectroscopy and Scanning Electron Microscopy (SEM) . All the experimental data were analysed using existing theoretical formalisms. The thesis is arranged in six chapters. The first chapter serves as a brief introduction to bioglasses and glass-ceramics, the materials of interest to this thesis work. The motivation behind the thesis work is briefly stated at the end of this chapter. The second chapter discusses the experimental techniques used in the presen...
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Supervisor: A. Srinivasan
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PHYSICS