Physical and Magnetic Characterization of Hard/Soft SrFe12O19/CoFe2O4 Nanocomposite Magnets Made by Mechanical Alloying and Ultrasonic Irradiation

Abstract

In this study, the particle sizes of SrFe12O19 in hard/soft SrFe12O19/CoFe2O4 nanocomposite magnets made using mechanical alloying and ultrasonic irradiation were investigated. SrFe12O19/CoFe2O4 nanocomposites were combined in a ratio of 75:25, with each magnetic material being prepared separately. SrFe12O19 powder was prepared from Fe2O3 and SrCO3 powder by mechanical alloying and ultrasonic irradiation for different times, 0, 3, 6, 9, and 12 h. Varying the ultrasonic time during the preparation of the SrFe12O19 samples resulted in differences in morphological characteristics, crystal structure, particle size, crystal size, microstrain, density, porosity, and magnetic properties. The longer the ultrasonic time, the crystal size and particle size decreases, the density increases, and the porosity reduction which affects the magnetic properties. SrFe12O19 after 12 h ultrasonic process reach Ms value = 61.29 emu/g. CoFe2O4 powder was produced from Fe2O3 and CoCO3 powder by mechanical alloying with a 10 h milling time. Furthermore, each SrFe12O19 sample was composited with CoFe2O4 powder by ultrasonic irradiation for 1 h and these composite samples also showed different characteristics, where there is an increase in Mr and Ms compared to the single SrFe12O19. The morphology, crystal structure, particle size, and magnetic properties of the samples were measured using scanning electron microscopy, X-ray diffraction, particle size analysis, and PERMAGRAPH. The crystal size and microstrain were calculated using a Williamson–Hall plot, and density and porosity were determined using Archimedes’ law.