Nagoya Institute of Technology

About: Nagoya Institute of Technology is a education organization based out in Nagoya, Japan. It is known for research contribution in the topics: Thin film & Catalysis. The organization has 10766 authors who have published 19140 publications receiving 255696 citations. The organization is also known as: Nagoya Kōgyō Daigaku & Nitech.

Structural investigation of keV Ar-ion-induced surface ripples in Si by cross-sectional transmission electron microscopy

Abstract: Using cross-section transmission electron microscopy (XTEM) we have studied the surface and subsurface structure of individual ripples having submicron scale wavelength and nanometer scale amplitude, generated by obliquely incident (50--120 keV) Ar ion bombardment of Si. The XTEM results reveal that the front slopes of ion-induced ripples have amorphous layers containing bubbles with sizes ranging from about 3 to 15 nm facing the ion beam direction. A thinner amorphous layer without bubbles, on the other hand, persists on the rear slope of ripples. We also observe an irregular interface between $a\ensuremath{-}\mathrm{Si}$ and $c\ensuremath{-}\mathrm{Si},$ which is due to the direct impact amorphization mechanism prevalent near the end-of-range during heavy ion irradiation.

Crushing of particles in idealised granular assemblies

Abstract: Four idealised assemblies of equally sized spherical particles are subjected to a range of macroscopic compressive principal stresses and the contact forces on individual particles are determined. For each set of contact forces the stress fields within individual particles are studied. A failure criterion for brittle materials is imposed and indicates that crushing (or rupture) occurs when the maximum contact force reaches a threshold particle strength value, irrespective of the presence and magnitude of other lesser contact forces acting on the particle and the material properties of the particle. Combining the crushing mechanism with an assembly instability mechanism enables failure surfaces to be drawn in the three-dimensional stress space. A simple spatial averaging technique has been applied to the failure surfaces to remove the effects of assembly anisotropies. Sections of the failure surfaces on π planes have similarities to those commonly used in sand modelling.

Occupational sites and dielectric properties of rare-earth and Mn substituted BaTiO3

Abstract: The effect of re-oxidation treatment on the solubility in dopants and the dielectric properties of La–Mn- and Ho–Mn-substituted BaTiO 3 ( AB O 3 ) was investigated. The lattice parameter and electrical resistivity results indicated that La ions occupied A -sites and Ho ions occupied both A - and B -sites. In the case of Ho–Mn-substituted samples, the decrease in lattice parameter and a shift of the Curie point ( T c ) to higher temperatures by re-oxidation treatment were observed in the range in which Ho ions predominantly occupy B -sites (act as acceptors). On the other hand, La–Mn-substituted samples showed little change. Electron spin resonance measurements revealed that these changes due to re-oxidation were based on the decrease of the ionic size of Mn due to the oxidation of Mn 2+ to Mn 3+ or Mn 4+ . The occupational sites of Ho ions strongly affected the valence state of Mn and the dielectric properties of BaTiO 3 .

Hybrid Improper Ferroelectricity in (Sr,Ca)3Sn2O7 and Beyond: Universal Relationship between Ferroelectric Transition Temperature and Tolerance Factor in n = 2 Ruddlesden–Popper Phases

Abstract: Hybrid improper ferroelectricity, which utilizes nonpolar but ubiquitous rotational/tilting distortions to create polarization, offers an attractive route to the discovery of new ferroelectric and multiferroic materials because its activity derives from geometric rather than electronic origins. Design approaches blending group theory and first principles can be utilized to explore the crystal symmetries of ferroelectric ground states, but in general, they do not make accurate predictions for some important parameters of ferroelectrics, such as Curie temperature (TC). Here, we establish a predictive and quantitative relationship between TC and the Goldschmidt tolerance factor, t, by employing n = 2 Ruddlesden–Popper (RP) A3B2O7 as a prototypical example of hybrid improper ferroelectrics. The focus is placed on an RP system, (Sr1–xCax)3Sn2O7 (x = 0, 0.1, and 0.2), which allows for the investigation of the purely geometric (ionic size) effect on ferroelectric transitions, due to the absence of the second-ord...

Two morphological types of cell appendages on a strongly adhesive bacterium, Acinetobacter sp. strain Tol 5.

Abstract: Two morphological types of appendages, an anchor-like appendage and a peritrichate fibril-type appendage, have been observed on cells of an adhesive bacterium, Acinetobacter sp. strain Tol 5, by use of recently developed electron microscopic techniques. The anchor extends straight to the substratum without branching and tethers the cell body at its end at distances of several hundred nanometers, whereas the peritrichate fibril attaches to the substratum in multiple places, fixing the cell at much shorter distances.