SYNTHESIS AND CHARACTERIZATION OF BARIUM-HEXAFERRITE NANOPARTICLES FOR MICROWAVE ABSORPTION

Abstract

Prior to its use for microwave absorption, a hard ferrite was synthesized and characterized. A mixture of iron oxide (Fe2O3) and barium carbonate (BaCO3) was milled using the mechanical alloying technique and sintered at a temperature of 900ºC for 10 hours to form barium hexaferrite (BaFe12O19). X-ray diffractometry (XRD), vibrating sample magnetometry (VSM) and scanning transmission electron microscopy (STEM) were used to investigate the crystalline phase formation, the material’s magnetic hysteresis-loop properties and particle size respectively. From the XRD results it is shown that at 900ºC the full phase of barium hexaferrite was formed. The VSM result shows that at a temperature as low as 900ºC, the saturation magnetization can achieve a value as high as 53.5 emu/g and the sample possesses a coercivity as high as 1071.9 Oe. The STEM result shows that the particle size is 300-400 nm. The high magnetization and coercivity values are good for large microwave absorption losses. Barium hexaferrite were mixed with magnetite to form composite. A suitable absorber giving high losses was formed to contain 15 wt% magnetite.