Synthesis of cobalt-rich alloys with high saturation magnetization: A novel synthetic approach by hydrazine reduction method

Abstract

Cobalt-rich alloys of various compositions (Co33Fe33Ni33, Co40Fe40Ni20, Co50Fe25Ni25 and Co60Fe20Ni20) were synthesized from their respective precursor salts using a novel hydrazine reduction method. The synthesized nanosized powders were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM) techniques. XRD phase analysis results revealed that the Co33Fe33Ni33 alloy was formed with a pure FCC phase. Whereas, Co40Fe40Ni20, Co50Fe25Ni25 and Co60Fe20Ni20 alloys were composed of both FCC and BCC phases. The average particle size of the alloys was estimated to be in the range of 107–280 nm. The synthesized cobalt-rich alloys exhibited ferromagnetic properties at room temperature with a high saturation magnetization value up to 138 emu/g. The mixed phase Co40Fe40Ni20 alloy showed higher saturation magnetization and higher coercivity as compared to the other alloy compositions. In mixed phase alloys, the dominance of the BCC phase over the FCC phase seems to has resulted in the enhancement of the saturation magnetization value. The obtained results indicate that the hydrazine reduction method was effective in synthesizing cobalt-rich alloys with excellent soft magnetic properties. Keywords: Cobalt-rich alloys, Hydrazine reduction method, Electron microscopy, Magnetic properties