Mangan ve Bor Tabanlı Üçlü Alaşımların Sentezi ve Hipertermi Uygulamalarının Araştırılması

Abstract

In this thesis, manganese-boron (MnB) which is a applicant for magnetic and transition metals (Zinc, Copper, Gadolinium and Iron) doped MnB ternary alloys which are an applicant for magnetic nanofluid hyperthermia, were synthesized and their structural, magnetic and hyperthermia properties were investigated. The Curie temperature and specific absorption rate (SAR) change were determined by changing the particles size and dopant metal. The starting alloys were prepared by arc melting method. X-ray powder diffractometer (XRD) and SEM-EDX were used for the structural characterization of the prepared samples. Phases and the crystal lattice parameters of the samples were obtained from MAUD program by making Reitveld analysis. Reitveld analysis showed that addition of Cu, Zn, Gd and Fe ions at different by atomic ratio were increased the crystal lattice parameters to the increase of the ratio. Backscatter pictures showed that different phase were formed in Cu and Gd doped samples. However for the Zn and Fe doped samples there is no contrast difference because of the phase separation which means mono-phase structure. Vibrating samples magnetometer (VSM) was used to determine the magnetic properties of the samples. Room temperature magnetization measurements showed a hysteresis curve with a saturation magnetization of 135 emu/g and a very low coercivity. The high temperature magnetization measurements showed the curie temperature as 566 K, With the addition of transition metals Cu, Zn, Gd, Fe with different atomic ratios, the saturation magnetizations of the bulk specimens were decreased to 88, 122, 113 and 129 emu/g and the Curie temperatures were measured as 568, 579, 567, 585 K, respectively. Room temperature magnetization measurements also showed that the coercivity always lover than 50 Oe for all doped samples Owing to their structural and magnetic properties, it has been determined that MnB and MnBFe (at %x; 0, 0.5, 1, 2) samples are the most suitable samples for hyperthermia application Bulk samples were milled to reduce the particle size. The crystallite sizes of the samples with milling times of 1, 3, 5 hours were calculated as 25, 18, 17 nm respectively by using Rietveld method from XRD measurements. Transmission electron microscope (TEM) was used to determine the particle sizes of the milled samples. For the 5 hours milled samples particle size calculated approximately 7 nm. The difference between the sizes calculated from XRD and TEM is because of the sample preparation deference for the measurement. For the TEM measurements samples dispersed in a solvent but for the XRD measurements samples were directly used. the bigger particles in the dispersion were collapsed so the mean particle size decreases. From the M-H and M-T measurements, the saturation magnetization decreased by degreasing the particle size but the Curie temperature did not change. To calculate the SAR values of the obtained nanostructured samples, the temperature change of the samples were measured under the AA (alternating current) magnetic field applied by a RF furnace. Sample of atomic 1% Fe doped and milling for 1 hour was showed a maximum SAR value of 34.5 W/g. When the SAR values of samples with a particle size of about 7 nm (5 hours milled) were compared, it was calculated that the highest atomic 0% Fe doped sample (MnB) had a value of 20.5 W/g. In this work, the synthesis, structural and magnetic properties of MnB-based ternary alloys were carried out in order to illuminate future work. Otherwise, In addition, manganese-boron and manganese-boron-based ternary alloys prepared as magnetic nanofluids are the guiding principles for the work to be carried out later.