12 research outputs found
Visualization of Three-Dimensional Ultrasonic Wave Fronts Using Holographic Interferometry
Preliminary survey of habitat use by Sciurus vulgaris orientis in a natural forest of Hokkaido Island, Japan
A new technique for the visualization of ultrasonic traveling wave by linearized subfringe interferometric holography
Preliminary estimation of population density of the Siberian flying squirrel (Pteromys volans orii) in natural forest of Hokkaido, Japan
Heat-treatment effect on the nanosized graphite π-electron system during diamond to graphite conversion
Graphite nanoparticles were prepared by the heat treatment of diamond nanoparticles in the range 900–1600°C. X-ray diffraction, Transmission Electron Microscopy (TEM) and Raman scattering studies indicate that the onset temperature of the diamond-graphite transition is around 1200°C and the complete conversion of diamond to graphite occurs at 1600°C. Based on the structural characteristics the samples are categorized into sp<sup>3</sup>-dominated (as-prepared and 900°C), sp<sup>2</sup>:sp<sup>3</sup> mixed-phase (1200 and 1400°C), and sp<sup>2</sup>-dominated systems (1600°C). The larger c-axis repeat distances and the high-resolution TEM images for the sp<sup>2</sup>:sp<sup>3</sup> mixed-phase systems denote the presence of the remnant buckling feature of the diamond (111) planes in the graphene sheets. Magnetic susceptibility and ESR studies suggest the development of itinerant-π-electron system from the 1200°C and higher-temperature heat-treated samples. The completely graphitized sample reveals the important role of edge-inherited nonbonding π-electron states in the electronic structure. The Raman G-peak position and the orbital diamagnetism show considerable deviation from the bulk-graphite values, which is explained on the basis of charge transfer from the graphite π band to the localized edge states and the resulting shifting of the Fermi level. The enhanced spin-lattice relaxation rates in the case of more graphitized samples heat-treated at 1400 and 1600°C are expected to arise from the involvement of the localized edge-state electrons. In the less-graphitized 1200°C heat-treated sample, however, the corrugated nature of the graphene planes is likely to hinder such fast-relaxation processes