Author Type

Graduate Student

Date of Award

2004

Document Type

Thesis

Publication Status

Version of Record

Submission Date

October 2026

Abstract

The structural, magnetic and microstructural properties of ferrimagnetic bioglass ceramics (FBC) in the system {0.45(CaO,P2O5) x (0.52-x)SiO2 x xFe 2O3 x 0.03Na2O} 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--1000C. 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 1100C. 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.

Extent

90 p.

Comments

FAU Electronic Theses and Dissertations Collection|Adviser: Theodora Leventouri.|Thesis (Ph.D.)--Florida Atlantic University, 2004.|FAU Electronic Theses and Dissertations Collection

Identifier

FADT12069

Format

pdf

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