The use of microwave (MW) irradiation to assist the modified peroxide sol-gel synthesis of La1-xSrxMnO3 was shown to 1)improve crystallinity and 2)enhance the magnetic susceptibility and magnetocaloric effect (MCE) of samples compared to those synthesised using the conventional method. The improvement in crystallinity of samples synthesised using MW irradiation was evident in the structural characterisation conducted using SEM and XRD. Magnetic heating experiments on La1-xSrxMnO3 (x = 0.25, 0.35 and 0.4) showed that for the MW-assisted method, the most suitable material for magnetic fluid hyperthermia applications was La0.65Sr0.35MnO3. MW settings (time and power) were investigated in an attempt to further optimise the MCE. Increasing MW time settings used (10 min, 30 min and 2 hours) led to increased saturation temperatures (45.9 °C, 57.0 °C and 58.3 °C respectively), with a linear relationship between the MW power settings used and the MCE also observed during magnetic heating experiments. Specific absorption rates as high as 175 Wg-1Mn were achieved compared to the conventional maximum of 56 Wg-1Mn in previous work. The enhancement of MCE was ascribed to a greater core ferromagnetic contribution as a result of the improvement in the degree of crystallinity and magnetic susceptibility of the samples synthesised with MW-irradiation .
Radio Frequency Heating of Magnetic Perovskite Nanoparticles in Solution for Biomedical ApplicationsAuthor: Cook, J., Jul 2020
Student thesis: Doctoral Thesis › Doctor of PhilosophyFile