INTERFACES BETWEEN CARBON NANOTUBES AND NICKEL NANOPARTICLES IN CARBON NANOTUBES

Carbon nanotubes (CNTs) filled with metals can be used in capacitors, sensors, rechargeable batteries, and so on. Their interface significantly affects the properties of the composites. Here, we show that three kinds of interfaces between crystalline Ni and CNTs exist, namely, ordered, distorted, and disordered. They presented lattice states of Ni atoms near the interface, whereas the (111)(Ni) plane was parallel to the CNTs' surface and appeared apart in a smaller or bigger angle. The coherent face-centered cubic (f.c.c)/hexagonal close-packed structure (h.c.p) boundary was formed between the crystalline Ni and CNTs at the ordered interface, in which the match was (111)(Ni)//(0001)(Carbon). We suggested a dislocation model for the coherent interface. The model explained why the angle between (200)(Ni) and the CNTs' inner surface was 52.9 degrees rather than the theoretical value of 54.75 degrees. The 1/2 [11 (1) over bar] dislocation was formed to fit the coherent relationship. Thus, Ni lattice shrinkage occurred. Further study indicated that the formation mechanism of crystalline Ni in CNTs was through heterogeneous nucleation on the inner wall surface and growth of the crystal nucleus.