Epitaxial thin films of 5 mol% Y-doped BaZrO3 (BZY5) proton conducting oxide were fabricated on MgO and Nb-doped SrTiO3 single crystal substrates using PLD method. Crystal structure, microstructure and electrical properties in in-plane and perpendicular directions of those films were studied. BZY5 is grown epitaxially over 700oC, and its epitaxial relationship is typical “Cube on Cube type”. TEM and AFM observations reveal that the films consist of columnar structure. Electrical properties in in-plain direction show significant lower conductivity and higher activation energy than that in perpendicular direction, and the properties are close to that of grain boundary in ceramics, while the electrical properties in perpendicular direction are similar to that of bulk in ceramics. These results suggest that the interfaces between columnar crystals even in epitaxial thin films prevent proton migration as the grain boundaries in ceramics do.
Widely well-defined Si(110)-16×2 single-domain surface has been fabricated utilizing the electromigration of the surface atoms. Tuning the direction of the dc during resistive heating to that of the surface reconstruction row realizes an alignment of the rows in one direction producing a mm-wide single-domain of 16×2 structure. The fabricated single-domain shows number of useful characteristics such as a strong one-dimensionality and the surface homochirality, suggesting various applications.
Angle-resolved photoemission measurements are carried out to investigate the valence electronic structures of two different ZnO surfaces that are (0001) Zn-terminated (ZnO-Zn) and (000-1) O-terminated (ZnO-O) surfaces, and also of Cu clusters supported on these surfaces. On the clean ZnO surfaces, two valence bands are observed at ∼4 and 5−8 eV with a clear dispersion feature. Although these bands are associated with the bulk bands, it is found that the dispersion widths of the bands exhibit the termination dependence of the polar ZnO surfaces. Deposition of Cu on the polar ZnO surfaces induces downward bending of the ZnO band. Magnitude of Cu-induced bending is larger on ZnO-O than on ZnO-Zn. This indicates that the Cu—ZnO interface interaction is greater for the Cu/ZnO-O system than for the Cu/ZnO-Zn system. The analysis of the Cu 3d band structure implies that coupling between the Cu 3d band and the ZnO band is operative at the Cu—ZnO-O interface, whereas such coupling seems to be missing at the Cu—ZnO-Zn interface. We propose that the effect of electronic coupling is one of the factors that determine the interface interaction between the Cu cluster and polar ZnO surfaces.
A femtosecond-laser-driven X-ray source and an X-ray focusing system have been developed for the time-resolved X-ray fluorescence spectroscopy. The X-ray source, in which a plasma cathode induced by a 1013-W/cm2 laser pulse serves as an electron source of an X-ray tube, provides 109 Cu Kα photons in 4πsr per pulse. The X-ray pulse duration is measured to be about two hundred nanoseconds. Emission analysis of the plasma cathode indicates that the temporal characteristics of the X-ray pulse are determined by the dynamics of the plasma particles under the electrostatic shielding against the applied voltage in the X-ray tube. As for the X-ray focusing system, a focal spot size by a polycapillary lens is measured and the enhancement of X-ray fluorescence intensity due to the lens is demonstrated.
We have investigated the formation of carbon nanotubes (CNTs) by the SiC surface decomposition method using transmission electron microscopy. When the SiC specimen was annealed at 1250oC for 1.0 h in an ultra-high vacuum, carbon nanofibers (CNFs) as well as CNTs were formed on the SiC(000-1) surface. However, when the specimen was annealed in oxygen, CNFs were not formed on the surface. These results indicate that oxygen is necessary for the CNT formation using the SiC surface decomposition method.
Self-assemble monolayers of binary molecules were studied by scanning tunneling microscopy. Di-indenoperylene (DIP) and fluorinated copper-phthalocyanine (F16CuPc), which are p-type and n-type organic semiconductors respectively, were co-deposited in ultra-high vacuum on Au(111) and Cu(111) surface. STM observation exhibited the molecules formed well-ordered intermixed monolayer on the metal surfaces. Theoretical calculation revealed C-F…H bonding between neighboring F16CuPc and DIP was a dominant force for the ordered phase formation. Orientation, alignment and domain formation were determined by balancing molecule-substrate interaction as well as such intermolecular interaction, and as a consequence showed dependency on the metal substrates and ratios of the molecules. Thus, the ordered phases were formed only at certain molecular ratios and were named as “molecular alloys” after those of inorganic materials.
The hair has a complicated hierarchical structure which is composed of hydrophobic and hydrophilic components. Study of the mechanical properties of each components is important in order to understand the structure of the hair microscopically and to develop hair care products. The objects of this study are to evaluate the mechanical properties and fine structures of human hair at the same point and under the natural environment by taking the advantages of Atomic Force Microscopy (AFM). The force-curve method using stiff cantilevers in order to deform a sample by AFM enable us to evaluate Young's modulus and a fine structure simultaneously at the same point. In this study, we applied this method also to the cross section of the hair in order to evaluate the degree of hair damage. In an application we found that the Young's modulus was improved when the damaged hair was treated by L-theanine solution and that especially Young's modulus of macrofibril was recovered. This method is thus very useful to appraise the effectiveness of hair care components.
This article is a brief introduction to a modern polarization theory and first-principles calculations of maximally localized Wannier functions. Practical calculations for these quantities are presented as well as a useful application to the downfolding problem with the ab initio Wannier functions.