Page 98 - Synthesis of Functional Nanoparticles Using an Atmospheric Pressure Microplasma Process - LiangLiang Lin

Chapter 5
nm). Their morphologies vary from nearly spherical to cubic. Besides, as indicated by the SAED pattern, they prove to be polycrystalline, and the diffraction rings are well assigned to the (111), (200), (220) and (311) planes of fcc Ni. Another noteworthy observation is that no CNTs appear in the products, in accordance with the SEM and XRD results.
Figure 5.5 Representative TEM and SAED images of products fabricated at various operation parameters: (a-b) 1.3 W, 35 ppm Ni(cp)2 vapor. (c-d) 3.4 W, 35 ppm Ni(cp)2 vapor. (e-f) 3.4 W, 17.5 ppm Ni(cp)2 vapor.
To give a better understanding of the influence of precursor concentration on particle morphology, TEM images of products synthesized at condition 8 are also provided in Figure 5.5 (e-f). Particles are shown to have various shapes (spherical, cubic, oval and irregular). The size is estimated to be in the range of 4-16 nm, which is smaller and more uniform compared with products obtained at double the precursor concentration (5-25 nm). In addition, the diffraction rings are also indexed to the (111), (200), (220) and (311) planes of fcc Ni nanoparticles, without the appearance of CNTs. However, due to their magnetic 86