A thin specimen of an amorphous lithium phosphorus oxynitride (LiPON) solid-state electrolyte sandwiched between two copper (Cu) plates was prepared using focused ion beam milling and narrow Ar-ion beam milling. In situ electron holography was used to observe changes of phase distributions in the LiPON film when different voltages were applied. Several models of electric potential distribution inside the specimen were tested and the resulting phase distributions simulated by integrating the 3D potential distribution along the electron trajectory through the thin Cu/LiPON/Cu region and external electric fields leaking from the specimen. The electric potential model that provided the best match to the experimental phase measurements was taken to represent the correct potential change within the specimen. Based on the precise potential changes, lithium-ion and lithium-vacancy distributions inside the LiPON layer were inferred.
Differential phase contrast scanning transmission electron microscopy (DPC STEM) now gathers considerable attention because this technique allows us to directly visualize electromagnetic fields inside materials and devices. In recent years, DPC STEM has been applied to atomic-resolution STEM, and electric field inside atoms, that is atomic electric field, has been shown to be observable in real space. In the present report, we would like to summarize theoretical understanding of atomic-resolution DPC image formation mechanisms and how to quantify such local fields by using segmented and pixelated detectors by investigating phase contrast transfer functions.
We have developed a method that is able to reveal the phase shifts of electron waves using an annular aperture and annularly arrayed detectors in scanning transmission electron microscopy (STEM). The reconstructed phase image using this method will have the potential for the observation of thick crystalline specimens within the kinematical approximation, since this technique has an expanded focal depth, which reduces the blurring. In this paper, we will introduce details of this method and the STEM system, and recent results.
Transmission electron microscope (TEM) has attracted much interest due to not only very high spatial resolution but also retrieving the phase information of the transmitted electron wave, which is helpful to understand the electrostatic potential and local electric or magnetic field around the specimen. Recently, the spatial resolution of TEM has been improved by the development of spherical aberration corrector. While, it has been still studied how to retrieve the phase information. In this paper, we introduce “transport of intensity equation (TIE)”, which enables us to retrieve the phase information from only three TEM images. We will discuss about the spatial resolution in TIE retrieved phase map, show the atomic resolved phase map of a MoS2 atomic sheet. Moreover, We will show that TIE method can be applied to retrieving the phase distribution at the interface between amorphous Ge layer and vacuum.
Irradiation techniques using ion-, electron-, and laser-beams can realize atomic configurations far from the equilibrium state, the so-called metastable phases, which are difficult to be obtained by conventional material synthesis techniques. The physical properties of materials strongly depend on atomic arrangements, and therefore knowledge of atomistic structures is required to synthesize new structural and functional materials. In addition, understanding structural changes of matter under radiation environments is of technological importance to predict performance and lifetimes of materials and to avoid serious accident. We have examined radiation-induced structural changes of various materials using transmission electron microscopy. In this article, we report our resent studies on (1) thermally-induced corundum-to-spinel phase transformation in Zr ion irradiated Al2O3 and (2) the enhancement of radiation tolerance in nanostructured SiC.
The human skeleton is a metabolically active organ that undergo continuous bone remodeling throughout life. The old bone is constantly being removed by osteoclasts and new bone is formed by osteoblasts. The activities of osteoclasts and osteoblasts are regulated under a strict balance to ensure normal bone mass. An imbalance in the bone resorption and bone formation results in metabolic skeletal diseases, such as osteoporosis. Osteoporosis is the most common metabolic skeletal disease, with very high fracture risk, especially among the elderly. This review article presents the age-related bone morphological changes in humans and the senile osteoporosis in experimental animals. We describe the trabecular and cortical bone microstructural parameters of the human vertebra, femur and tibia with age. We also discuss morphological and molecular biological alterations in senile osteoporosis model, the senescence-accelerated mouse prone P6 (SAMP6). Osteocyte is an important orchestrator of the bone remodeling. The peroxisome proliferator-activated receptor γ and secreted frizzled-related protein 4 (SFRP4) might be related to the lower bone mass in SAMP6.
The mucosal surface of intestine is mainly covered by absorptive cells (enterocytes) which absorb nutrients and water from its lumen. The cells are present throughout intestine and have common structural characterization; however, its function varies in its location. In the rodents, the absorptive cells have different feature between adult and suckling period. In the suckling rodents, the absorptive cells alter intracellular structure along with proximo-distal (canoniocaudal) axis. We focused on the absorptive cells of distal small intestine (ileum) in suckling rodents. The cells specialize for apical endocytosis of macromolecules from maternal milk. After weaning, the absorptive cells that have apical endocytic membrane system disappear in the epithelium. According to the unique property, we applied organoid technologies on ileum.
A survey on electron lens designing methods is presented in two consecutive articles. In the first article, we explained the fundamentals of optical design and showed that short focal length was the key strategy to reduce the aberration of the objective lens for high resolution SEMs. Electrostatic and magnetic field complex lenses such as retarding and boosting are effective for short focus length. In this second article, the design simulation procedure of field complex lenses and examples of specific optimization are explained at the beginning. In the latter half, we summarize the technology necessary for mounting magnetic lenses which are the most frequently used for TEMs.
We have succeeded in developing an entirely new microscopy technique of visualizing photoinduced carrier dynamics, including spins, by integrating the scanning tunneling microscopy (STM) technique and the quantum optics technique. By the developed technique, the local structures and electronic states of atoms and molecules can be observed with femtosecond time resolution and the atomic-level spatial resolution of STM. In this paper, we discuss the present and future of this field by overviewing the new microscopy techniques and those for the THz-STM which we have been developing.
In order to obtain higher contrast image from bio-nano particles, we have developed electron microscope with lower beam energy. Additionally, we employed employing in-line holography. By means of FFT based image reconstruction, we may obtain complex object amplitude, thus phase object image at higher contrast. We started to observe bio-nano particle at nano-meter resolution.We are currently focus to improve sample preparation technique.