Preparation and magnetic properties of amorphous Co–Cu–B alloy nano-powders

Magnetic Co–Cu–B powders were successfully prepared by the reduction of copper chloride and cobalt chloride in an aqueous solution of sodium borohydride. Using X-ray diffraction (XRD), selective area electronic diffraction (SAED), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS) it was shown that, when Co2+/Cu2+ ratio in the original mixed solution was greater, the resultant powders were amorphous alloy powders, having a nearly spherical morphology with diameters <50 nm. DSC trace of the as-prepared Co–Cu–B ultrafine amorphous alloy powders showed only one exothermic peak, and no sharp glass transition temperature could be identified. From the room-temperature magnetic hysteresis loops measured by vibrating sample magnetometer, it was found that the Co–Cu–B amorphous alloy powders exhibited hard magnetic behavior, and the saturation magnetization could be further improved by crystallization.