**7. Summary of the Nanostructure Evolution and Manipulations in the Electron Excited Field**

Research conducted by my group on nanostructure evolution by electron beam irradiation from 1995 to 2005 was reviewed. I have utilised electron beams in TEM to synthesise nanomaterials and manipulate their nanostructures, in addition to observing and analysing nanostructures. An overview of the effects of electron irradiation is presented in Figures 28 and 29, where the abscissa is expressed as the electron irradiation intensity on a logarithmic scale. The electron beam was focused for synthesis and manipulation up to 10 <sup>19</sup>–10<sup>24</sup> e/cm<sup>2</sup> s, which is higher than 10<sup>16</sup> e/cm<sup>2</sup> s generally used for electron diffraction and 10<sup>18</sup> e/cm<sup>2</sup> s used for bright-field imaging.

Figure 28 shows that electron irradiation of metastable θ-Al2O<sup>3</sup> provides oxide-free Al nanoparticles, rod-like α-Al2O3, and encapsulated nanoparticles, whereas flashing mode provides θ-, δ-Al2O<sup>3</sup> nanoball/nanowire complexes. The formation of W nanoparticles from WO<sup>3</sup> requires a higher intensity of more than 10<sup>23</sup> e/cm<sup>2</sup> s. Electrons traveling in a spiral trajectory in the magnetic field of the pole piece transfer momentum to the Al nanoparticles enable various types of manipulation, such as migration, bonding, rotation, revolution, embedding, fullerene formation, and intercalation. The intensity is also more than 100 times higher than that of normal observation conditions, as shown in Figure 29. The combination of such syntheses and manipulation will provide more complicated nanostructures for future applications.

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**Figure 28.** Nanostructured materials obtained by electron irradiation in TEM. Nanoparticles and nanosized oxides can be induced in an electron excited reaction field. The electron irradiation intensity ranged from 1020–1023 e/cm2s depending on the specific gravity of the materials and the metal-oxygen binding enthalpy of the starting oxide. **Figure 28.** Nanostructured materials obtained by electron irradiation in TEM. Nanoparticles and nanosized oxides can be induced in an electron excited reaction field. The electron irradiation intensity ranged from 1020–10<sup>23</sup> e/cm<sup>2</sup> s depending on the specific gravity of the materials and the metal-oxygen binding enthalpy of the starting oxide. **Figure 28.** Nanostructured materials obtained by electron irradiation in TEM. Nanoparticles and nanosized oxides can be induced in an electron excited reaction field. The electron irradiation intensity ranged from 1020–1023 e/cm2s depending on the specific gravity of the materials and the metal-oxygen binding enthalpy of the starting oxide.

**Figure 29.** Manipulation of nanomaterials by electron irradiation in a TEM. Nanostructures can be controlled in an electron excited reaction field through migration, bonding, rotation, revolution, embedding, fullerene formation and **Figure 29.** Manipulation of nanomaterials by electron irradiation in a TEM. Nanostructures can be controlled in an electron excited reaction field through migration, bonding, rotation, revolution, embedding, fullerene formation and intercalation. The electron irradiation intensity ranged between 1019–1023 e/cm2s depending on the size and weight of the **Figure 29.** Manipulation of nanomaterials by electron irradiation in a TEM. Nanostructures can be controlled in an electron excited reaction field through migration, bonding, rotation, revolution, embedding, fullerene formation and intercalation. The electron irradiation intensity ranged between 1019–10<sup>23</sup> e/cm<sup>2</sup> s depending on the size and weight of the material.
