Emission sites were observed as bright spots near the tip end of a multiwalled carbon nanotube (MWNT) by means of Lorenz microscopy. The bright spots appeared above electric fields as electrons were emitted. A marked fluctuation was observed in the emission current above 20–30 µA, which was closely related to structural changes at the tip of the MWNT. The layers of the MWNT were peeled off during field emission and they functioned as the second emission sites for the concentration of electric field.

In situ observation of field emissions from an individual carbon nanotube (CNT) was performed by Lorenz microscopy. A bright spot appeared by Lorenz microscopy at the end of the CNT tip during field emission. The bright spot is assumed to be related to the emission site on the CNT. A drastic fluctuation was observed in the emission current above a few tens of microamperes, which was closely related to structural changes at the tip of the CNT. The layers of the CNT were peeled off and they worked as a second emission site by concentration of the electric field.

Nano sized processing is reported to realize distinctive features in physical properties. We found a remarkable microwave absorption property caused by the increase of permeability and permittivity when nanogranulating ferromagnetic metals (Fe) and high electrical resistance ceramics (SiO 2 ) in the frequency range of GHz. In this paper, we report the microwave absorption properties is effected by the dispersion state of Si oxides in Fe SiO 2 nanogranular powder and the improvement of the microwave absorption properties by nanocompositing Fe and SiO 2 is caused by the diffusion between Fe nanocrystal grains and amorphous Si oxides in MA process.

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