This study demonstrates the accumulation of electron-induced secondary electrons by utilizing a simple geometrical configuration of two branches of a charged insulating biomaterial. The collective motion of these secondary electrons between the branches has been visualized by analyzing the reconstructed amplitude images obtained using in situ electron holography. In order to understand the collective motion of secondary electrons, the trajectories of these electrons around the branches have also been simulated by taking into account the electric field around the charged branches on the basis of Maxwell’s equations.

The charging effects of microfibrils of sciatic nerve tissues due to electron irradiation are investigated using electron holography. The phenomenon that the charging effects are enhanced with an increase of electron intensity is visualized through direct observations of the electric potential distribution around the specimen. The electric potential at the surface of the specimen could be quantitatively evaluated by simulation, which takes into account the reference wave modulation due to the long-range electric field.

Nanoparticles of iron carbides (Fe3C and χ-Fe2.5C) wrapped in multilayered graphitic sheets were synthesized by a developed method in which an electric plasma was generated in an ultrasonic cavitation field containing thousands of tiny activated bubbles in liquid ethanol. Annealing changed the phase composition, structure, and size of the carbon nanocapsules as most of the iron carbides decomposed into the α-Fe phase and graphite. Powder samples annealed at 873 and 973 K have maximal saturation magnetization values equal to 80.6 and 83.4 A m2/kg, respectively, which is approximately 40% of the value of bulk iron. Using this method, it will be possible to synthesize nanoparticles of a metal of choice encapsulated by graphite shells by selecting appropriate materials for the ultrasonic tip and electrodes.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

The microstructure and magnetic domain structure of a Co-CoO obliquely evaporated tape for magnetic recording are studied by analytical electron microscopy and electron holography, respectively. While the existence of Co and CoO crystallites is confirmed by energy-filtered electron diffraction, columnar structure of the Co crystallites surrounded by the densely packed CoO crystallites is visualized by an elemental mapping method with electron energy loss spectroscopy, and the crystal orientation relation among the Co crystallites is clarified by high-resolution electron microscopy. It is found that the neighboring Co crystallites have close crystal orientations. On the other hand, electron holography reveals the magnetic flux distribution in a thin section of the tape. Although there exists the background resulting from the effect of inner potential with thickness variation, the distribution of lines of magnetic flux is found to correspond well to the recorded pattern.

The following is a Web Extra expanding upon the article “Understanding Precursor Phenomena for the R-Phase Transformation in Ti-Ni-Based Alloys” by Daisuke Shindo, Yasukazu Murakami, and Takuya Ohba, published in MRS Bulletin27 (2002) pp. 121–127. It provides a closer examination of the domain structure evolution over a temperature range extended beyond that shown in Figure 5 in the article, along with intensity profiles of the electron diffraction.

Precursor phenomena are critical issues for martensitic transformations. In this article, we show recent progress in understanding precursor phenomena to the R-phase transformation, which is important for both fundamentals and applications. Structural modulation in the parent phase was intensively studied by means of detailed analyses of the weak diffuse scattering of electrons with the aid of recently developed energy-filtered transmission electron microscopy coupled with x-ray diffraction. A peculiar domain-like structure, which originates from static transverse atomic displacements in the parent phase, was discovered by virtue of these advanced methods. The characteristics of this structure (e.g., size, shape, and temperature-dependence), as well as its role in the subsequent R-phase transformation, are discussed.