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Processing, Magnetization and Structural Studies of Bioactive Ferromagnetic Glass-Ceramics Theodora Leventouri, Antonella C. Kis, Korey Sorge1, Camelia E. Bunaciu, and James R. Thompson1 Physics Department, Florida Atlantic University, Boca Raton, FL 33431, U.S.A. 1 Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830-6061, U.S.A, and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996-1200, U.S.A. ABSTRACT A series of ferromagnetic bioceramic samples in the system 45(CaO, P2O5), ySiO2 xFe2O3 were synthesized with various processing parameters in order to study correlations between structure, magnetic properties and preparation variables. X-ray powder diffraction shows that the qualitative as well as the quantitative structure of the samples is strongly affected by processing parameters, including composition, annealing temperature and the chemical reactions. Magnetic measurements illustrate a strong correlation between the saturation magnetization, and hysteresis loss, with the processing parameters of the material.

INTRODUCTION Ferromagnetic glass ceramics are biocompatible and bioactive materials, which have been fabricated from bioglass ceramics [1] with the addition of Fe2O3 in the system [SiO2, P2O5, CaO]. The bioactivity of these multiphase systems originates from the calcium phosphate [Ca3(PO4)2] which forms apatite [Ca5(PO4)3OH] in a physiological environment. Their magnetic properties have been shown to be effective in hyperthermic treatment of animal bone cancer [28]. Heat is generated by hysteretic ferromagnetic loss when an oscillating magnetic field is o applied. The amount of the generated heat is enough to locally raise the temperature to 42-45 C. The effectiveness of hyperthermic treatment is related to the fact that cancer cells heat-treated at that temperature have a much smaller chance of survival than ordinary tissues. Here we report on some preliminary results from our research on the correlations between processing parameters, structure, and magnetic properties in ferromagnetic bioceramics.

EXPERIMENTAL A series of samples were prepared by a method of melting and quenching with various processing parameters. Table I lists the samples from three sample series. Sample series AK1 was prepared by mixing the appropriate portions of the reagent-grade chemicals CaHPO4.2H2O, CaCO3, SiO2 and 10% of Fe2O3 in a corundum crucible. The mixture was melted at ~1500 oC and kept in the furnace for approximately 30 min. Then it was quenched at room temperature by pouring the melt on stainless steel plates [9]. HH3.20.1

Table I. Three series of ferromagnetic bioceramics AK1, AK3, AK4 with different compositions. Samples from each series were annealed at several temperatures from 700 to 1000 o C and named accordingly.

Series AK1 chemicals: CaHPO4.2H2O, CaCO3, SiO2, Fe2O3 starting composition 45(CaO.P2O5).45SiO2.10Fe2O3 AK1 700 AK1 850 AK1 900 AK1 950 AK1 1000

SAMPLES Series AK3 chemicals: Ca(OH)2, Ca2P2O7, SiO2, Fe2O3 starting composition same as in AK1 AK3 700 AK3