Preparation And Characterization Of Nano Magnetic Materials Based On Carbon Nanotubes

Due to the powerful vitality and extensive application prospect of nanometer-scale magnetic materials in many fields, its study is one of the fast progressive areas in physics, chemistry, and material science etc. The carbon nanotubes(CNTs) is a favorable kind of host material in nano areas for their unique characters and special tube structure made of graphite flakes. It is an important research subject to develop a new method of preparation nanometer-scale magnetic materials.In this paper, a simple method—electroless plating was applied to coat CNTs with Ni-P, Co-P, Co-Ni-P and Co-Fe-P for the first time. A new one-dimensional nanometer -scale magnetic materials was obtained. The results have realistic significance to apply in further. Based on the pretreatment, the optimum experimental methods and technique for getting continuous and compact encapsulating layer were determined, and the influences of processing conditions and technique on the composition, crystal structure and uniformity of the encapsulating layer were analyzed. The relationship between crystal structure and magnetic properties were studied. The coating were characterized by scanning electron microscopy(SEM), transmission electron microscopy (TEM), X-ray energy dispers spectrum(EDX) and the vibrating sample magnetometer (VSM) etc. The conclusions are as follows:(1) The magnetic alloy was deposited on the surface of CNTs by an electroless deposition method. The method was simple and feasible, and could make the encapsulating layer continuous and even.(2) The key to obtain the continuous encapsulating layer were pretreatment, high-density activated sites, low deposition rate, the optimum load ratio and dispersed means.(3) The important factors of magnetic properties were temperature, pH value, molar ratio of plating bath composition. The elements content of encapsulating layer could be adjusted by molar ratio controlling of plating bath composition. And its magnetic properties could be controlled accordingly.(3) The continuous and compact Ni-P encapsulating layer could be obtained by inducing-activation method. But it is more difficult to initiate coating and control than sensitizing-activation method.(5) The coercivity and specific saturation magnetization of CNTs could improve apparently after encapsulation. The coercivity of encapsulating layer was much higher than coarse powder and bulk alloy. That is new effects of nanometer-scale.(6) Heat treatment, which can achieve the smooth, continuous and compact encapsulating layer, were found to be critical for getting better magnetic properties.