Page 61 - Synthesis of Functional Nanoparticles Using an Atmospheric Pressure Microplasma Process - LiangLiang Lin

Iron Oxide Nanoparticles Synthesis and Mechanism Study - a Proof-of-Concept Model Study
Figure 3.6 TEM images of nanoparticles synthesized at plasma power of 1.05 W (a) and 2.27 W (b)
Figure 3.7 shows TEM images of nanoparticles synthesized at oven temperatures of 323.15 K (a) and 339.15 K (b), respectively. The total gas flow rate is 100 ml/min, with ferrocene concentration of 29.0 ppm and 98.5 ppm, respectively. Plasma power is kept constant at 1.05 W. Similar to Figure 3.6, TEM results in Figure 3.7 show that nanoparticles are connected together, with no single particle being found in the field of views. Besides, particles prepared at lower precursor concentration are smaller in diameter, with lower apparent agglomeration degree. This was also observed by Chiang et al., who used metallocene to prepare bimetallic nanoparticles, where higher precursor concentration lead to larger size particles.12
Figure 3.7 TEM images of nanoparticles synthesized at ferrocene concentration of (a) 29.0 ppm and (b) 98.5 ppm.
Figure 3.8(a) shows a typical HRTEM image of particles synthesized at oven temperature of 323.15 K and plasma power of 1.05 W. The image confirms that particles are crystalline and nanometer-sized. The characteristic size of the nanoparticles is in the range of 8-10 nm. As can be seen from the image, there are several patterns of atoms, indicating polycrystalline nature of the nanoparticles. Lattice spaces corresponding to the (104) and (220) planes of iron oxides (Maghemite or Magnetite) were clearly observed. However, due to the
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