Composition Dependent Magnetic Properties of Ni-Co-P Coated Carbon Nanotubes

Carbon nanotubes were coated with a layer of nickel-cobalt-phosphorus (Ni-Co-P) alloy with different compositions of Ni/Co through electroless plating. The effects of the concentration ratio of Co²⁺to Ni²⁺, bath temperature, and pH on deposition rate are discussed. The prepared carbon nanotubes covered with Ni-Co-P were characterized and analyzed by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and a vibrating sample magnetometer. The results show that the deposition rate reached the maximum when the concentration ratio of Co²⁺to Ni²⁺ is 1 and the pH is 9; the deposition rate increases with the increase of bath temperature. The measurements of the magnetic properties of the obtained carbon nanotubes covered with Ni-Co-P indicate that the magnetic properties greatly depend on the concentration ratio of Co²⁺to Ni²⁺and the magnetic saturation reaches the maximum value when the Co²⁺to Ni²⁺ ratio is 1. In addition, there are two peaks in the coercivity curve at Co²⁺to Ni²⁺ ratios of 1/2 and 4/1, while the two peaks in the magnetic conductivity curve are located atCo²⁺to Ni²⁺ ratios of 1/4 and 4/1.