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Journal Articles

Plasmonic cyclohexane-sensing by sputter-deposited Au nanoparticle array on SiO$$_{2}$$

Kawaguchi, Kazuhiro*; Yamamoto, Shunya; Yoshikawa, Masahito; Takahiro, Katsumi*

Thin Solid Films, 562, p.648 - 652, 2014/07

 Times Cited Count:4 Percentile:22.6(Materials Science, Multidisciplinary)

Liquid organic-hydrides such as cyclohexane which can release-absorbing hydrogen in reversible have been proposed approvable carriers to store and transport hydrogen. However, organic-hydrides are known as highly flammable in air. To realize practical use of this hydrogen production process, the monitoring of leakage of organic-hydride gas is strongly required. In the present work, we have examined the plasmonic sensing ability of Au nanoparticle (NP) arrays for dilute cyclohexane. Au NP arrays were prepared on SiO$$_{2}$$ by a sputter deposition technique. The change in an extinction spectrum of Au NP arrays before and after exposure of cyclohexane vapor enabled us to detect it. The Au NP array prepared with 4.4 $$times$$ 10$$^{16}$$ Au atoms/cm$$^{2}$$ deposited at 300$$^{circ}$$C was and demonstrated a high sensitivity for cyclohexane at RT. The experimentally detectable concentration of cyclohexane was as low as 0.5 vol%, much lower than its explosion limit (1.3 vol%).

Journal Articles

Preparation of tungsten carbide nanoparticles by ion implantation and electrochemical etching

Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*

Nuclear Instruments and Methods in Physics Research B, 314, p.149 - 152, 2013/11

 Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)

We implanted 100 keV W$$^+$$ in unpolished GC substrates at nominal fluences up to $$1.7times10^{17}$$ ions/cm$$^2$$. The implanted samples were electrochemically anodized in a NaOH aqueous solution to etch the surface layer. The analyses were performed by X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectrometry (RBS), and transmission electron microscopy (TEM). XPS W 4f spectra indicated the formation of carbides as reported previously. The electrochemical etching clearly increased the W concentration on the surface. According to the RBS results, half of the implanted W atoms were retained in the substrate, while the rest should escape to the etching solution. The cross-sectional TEM image revealed a uniform distribution of WC particles with a diameter of less than 10 nm just near the surface region.

Journal Articles

Nanoparticle formation by tungsten ion implantation in glassy carbon

Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*

Transactions of the Materials Research Society of Japan, 38(1), p.81 - 84, 2013/03

Nanoparticles were formed by 100 keV tungsten-ion implantation in unpolished glassy carbon substrates at nominal fluences of $$2.4times10^{16}$$ - $$1.8times10^{17}$$ ions/cm$$^2$$. The implanted samples were analyzed by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, hydrodynamic voltammetry using a rotating disk electrode, and field emission scanning electron microscopy. A significant sputtering effect changed the depth profile during the course of irradiation and limited the amount of tungsten retainable in the substrate in agreement with our calculated distributions. The nanoparticles were composed of tungsten carbide and dispersed uniformly with diameters of around 10 nm.

Journal Articles

Well-ordered arranging of Ag nanoparticles in SiO$$_{2}$$/Si by ion implantation

Takahiro, Katsumi*; Ninakuchi, Yuki*; Kawaguchi, Kazuhiro; Isshiki, Toshiyuki*; Nishio, Koji*; Sasase, Masato*; Yamamoto, Shunya; Nishiyama, Fumitaka*

Applied Surface Science, 258(19), p.7322 - 7326, 2012/07

 Times Cited Count:2 Percentile:11.18(Chemistry, Physical)

A nanometer-sized metallic particle embedded in a transparent dielectric exhibits a nonlinear susceptibility, and going to be applied to nonlinear optical devices. In the present study, well-ordered arrangements of Ag nanoparticles have been found for Ag-implanted SiO$$_{2}$$. Thermally grown SiO$$_{2}$$ on Si were implanted with 350 keV-Ag ions to fluences of 0.37-1.2 $$times$$ 10$$^{17}$$ ions/cm$$^{2}$$. Cross-sectional transmission electron microscopy and scanning transmission electron microscopy reveal the presence of a two-dimensional array of Ag nanoparticles of 25-40 nm in diameter located at a depth of $$sim$$130 nm, together with the self-organization of tiny Ag nanoparticles aligned along the SiO$$_{2}$$/Si interface. X-ray photoelectron spectroscopy and X-ray diffraction confirm the stability of these Ag nanoparticles embedded in the SiO$$_{2}$$/Si is found to be stable against oxidation and sulfidation when stored in ambient conditions for more than one and a half year.

Journal Articles

Blueshift and narrowing of localized surface plasmon resonance of silver nanoparticles exposed to plasma

Kawaguchi, Kazuhiro; Saito, Masahiro*; Takahiro, Katsumi*; Yamamoto, Shunya; Yoshikawa, Masahito

Plasmonics, 6(3), p.535 - 539, 2011/09

 Times Cited Count:7 Percentile:28.03(Chemistry, Physical)

Silver nanoparticles (Ag NPs) have optical absorption bands due to localized surface plasmon resonance (LSPR) in visible range. The LSPR of Ag-NPs is being used for optical gas sensors. However, there have been differences in LSPR absorption band between most of the experimental data and calculations. We have demonstrated that plasma treatments for Ag NPs to clear the effect of contamination on surface of Ag NPs for LSPR absorption band. The results show that Ar plasma treatments to Ag NPs bring blue-shift and narrowing in their LSPR absorption band. Raman scattering analysis result that hydrocarbons adsorbed on silver surfaces were removed effectively by plasma exposure. It was found that the decrease in Raman line intensity for hydrocarbons was correlated well with the blue-shift. Our findings indicate that one of the most important factors for difference in LSPR absorption band between the experimental data and calculations is due to the impurity adsorption on silver surfaces.

Journal Articles

Oxygen reduction activity of N-doped carbon-based films prepared by pulsed laser deposition

Hakoda, Teruyuki; Yamamoto, Shunya; Kawaguchi, Kazuhiro; Yamaki, Tetsuya; Kobayashi, Tomohiro*; Yoshikawa, Masahito

Applied Surface Science, 257(5), p.1556 - 1561, 2010/12

 Times Cited Count:12 Percentile:51.43(Chemistry, Physical)

Carbon-based films having nitrogen species on their surface were prepared on a glassy-carbon (GC) substrate as a non-platinum cathode catalyst for polymer electrolyte fuel cells by depositing cobalt and carbon in the presence of N$$_{2}$$ gas using a pulse laser deposition method and then removing metal Co by HCl-washing treatment. The oxygen reduction reaction (ORR) activity was electrochemically determined using a rotating disk electrode system where the film samples on the GC substrate were replaceable. The ORR activity increased with elevating temperature of the GC substrate during the deposition. A carbon-based film prepared at 600$$^{circ}$$C in the presence of 66.7 Pa N$$_{2}$$ showed the highest ORR activity among the tested samples; its ORR potential was 0.66 V (vs. NHE). This film was composed of amorphous carbons doped with pyridine-type nitrogen atoms on its surface.

Journal Articles

Development of optical fiber detector for measurement of fast neutron

Yagi, Takahiro*; Misawa, Tsuyoshi*; Pyeon, C. H.*; Unesaki, Hironobu*; Shiroya, Seiji*; Kawaguchi, Shinichi*; Okajima, Shigeaki; Tani, Kazuhiro*

Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09

In order to insert a neutron detector in a narrow space such as a gap of between fuel plates and measure the fast neutrons in real time, a neutron detector with an optical fiber has been developed. This detector consists of an optical fiber whose tip is covered with mixture of neutron converter material and scintillator such as ZnS(Ag). The detector for fast neutrons uses ThO$$_{2}$$ as converter material because $$^{232}$$Th makes fission reaction with fast neutrons. The place where $$^{232}$$Th can be uses is limited by regulations because $$^{232}$$Th is nuclear fuel material. The purpose of this research is to develop a new optical fiber detector to measure fast neutrons without $$^{232}$$Th and to investigate the characteristic of the detector. These detectors were used to measure a D-T neutron generator and fast neutron flux distribution at Fast Critical Assembly. The results showed that the fast neutron flux distribution of the new optical fiber detector with ZnS(Ag) was the same as it of the activation method, and the detector are effective for measurement of fast neutrons.

Journal Articles

Conceptual design study and evaluation of advanced fuel fabrication systems in the feasibility study on commercialized FR fuel cycle in Japan

Namekawa, Takashi; Kawaguchi, Koichi; Koike, Kazuhiro; Haraguchi, Shingo; Ishii, Satoru

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

New concepts of future fabrication system for low decontaminated transuranium (TRU) fuel was designed. It is essential to establish a remote fabrication system in the hot cell, because materials with high levels of radiation and high generation of heat are handled in the system. The configuration of the present systems including aspects related to economy was clarified through the conceptual design study. Technical feasibility of each concepts is follwiong. For oxide fuels, the simplified pelletizing method has a high technical feasibility for the process, and its expected practical use is possible at early stage, because this method is based on wealth results of a conventional method. The sphere-pack method has the advantage of lesser dispersion of the fine powder due to the use of solution and granule in the process. However this system will shoulder additional cost for the liquid waste treatment process due to need dispose of a large bulk of process liquid waste. The vipack method has the possibility of economical improvement if simplification of the process can be achieved. However this system has some problems for quality assurance etc. For the casting method of metal fuel, high economical efficiency is generally expected of small-scale facilities, although verification of fabrication of the TRU alloy slug is required. For nitride fuel, technology developments for N-15 enrichment and recycling, and nitride conversion process etc. In particular, for coated particle fuel fabrication, crucial technology developments are required on coating and assembly process.

Journal Articles

Advanced Fuel Fabrication System Concepts Using Advanced-Aqueous-Reprocessing Product (full paper)

; Kawaguchi, Koichi; Koike, Kazuhiro

pp1354, 0 Pages, 2003/00

The conceptual design study for advanced pelletizing system and shere-pac system,has been performed in consideration of basic process viability. Through the design of fuel pin fabrication line,it has been shown that fuel preparation equipment consists of various process devices has proper capacity. Comparing the advanced pelletizing system with sphere-pac system,the pelletizing system has cost advantage over sphere-pac system. However there is no extreme difference of TRU solid waste amount estimation between both systems.

Oral presentation

Radiation effects of the boron nano-belt on the electronic conductivity

Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi

no journal, , 

Radiation effects of the boron nano-belt on the electronic conductivity have been studied.

Oral presentation

Radiation detection using boron nanobelts

Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi

no journal, , 

We discuss the effects of neutron and $$gamma$$-ray irradiation on electrical transport of single-crystalline boron nanobelts toward a nano-scale radiation sensor device. Changes of electrical conductance of individual nanobelt before and after thermal neutron irradiation with low (10$$^{8}$$ cm$$^{-2}$$ s$$^{-1}$$) or high (3$$times$$10$$^{13}$$ cm$$^{-2}$$ s$$^{-1}$$) flux are presented.

Oral presentation

Effect of neutron irradiation on the electrical transport of boron nanobelt devices

Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi

no journal, , 

Isotopic $$^{10}$$B atom has large thermal neutron capture cross section. $$^{7}$$Li atom and $$alpha$$ particle as a product of the neutron reaction can change the electrical transport property of the boron-rich semiconductor because they provide carrier doping and lattice defects. We successfully synthesized catalyst-free single-crystalline boron nanobelts (BNBs) and clarified the electrical transport and photoconduction mechanism of individual nanobelt. The BNB device is promising candidates for solid-state neutron sensors with both high resolution and good discrimination performance between neutron and $$gamma$$-ray. In the presentation, we discuss the performance of thermal neutron detection of BNB devices. Isotopic $$^{10}$$B enriched BNBs was synthesized to detect thermal neutrons efficiently. Electrical conductance of a nanobelt increased to eight times after the thermal neutron irradiation with a dose of 1.8$$times$$10$$^{14}$$ cm$$^{-2}$$ by the neutron reaction of $$^{10}$$B.

Oral presentation

Formation of Au and Pt nanoparticles on ion irradiated graphite substrates

Takahiro, Katsumi*; Morimoto, Keiichi*; Yasuda, Kenji*; Kawaguchi, Kazuhiro; Nagata, Shinji*; Yamamoto, Shunya; Narumi, Kazumasa; Naramoto, Hiroshi*

no journal, , 

no abstracts in English

Oral presentation

Modification of Ag nanoparticles on SiO$$_{2}$$ substrate by ion irradiation

Kawaguchi, Kazuhiro; Yoshimura, Kimio; Yamamoto, Shunya; Yoshikawa, Masahito; Takahiro, Katsumi*

no journal, , 

no abstracts in English

Oral presentation

Preparation of carbon based cathode catalyst by pulsed laser deposition

Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Yamaki, Tetsuya; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Modification of Ag nanoparticles on SiO$$_{2}$$ substrate by ion irradiation

Kawaguchi, Kazuhiro; Takahiro, Katsumi*; Yoshimura, Kimio; Yamamoto, Shunya; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Effect of ion beam irradiation on optical properties of Ag nanoparticles

Kawaguchi, Kazuhiro; Takahiro, Katsumi*; Yamamoto, Shunya; Hakoda, Teruyuki; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Hydrogen gasochromism of WO$$_{3}$$ films prepared by reactive sputtering

Yamamoto, Shunya; Kawaguchi, Kazuhiro; Sugimoto, Masaki; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Oxygen reduction activity of N-doped carbon based films prepared by pulsed laser deposition

Hakoda, Teruyuki; Yamamoto, Shunya; Kawaguchi, Kazuhiro; Yamaki, Tetsuya; Kobayashi, Tomohiro*; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Fabrication and evaluation of light-emitting SiO$$_{2}$$ substrates implanted with Ge ions

Shinagawa, Teruyoshi*; Umenyi, A. V.*; Kikuchi, Shusuke*; Aiba, Mizuki*; Inada, Kazuki*; Miura, Kenta*; Hanaizumi, Osamu*; Yamamoto, Shunya; Kawaguchi, Kazuhiro; Yoshikawa, Masahito

no journal, , 

Light emission between ultraviolet and blue from SiO$$_{2}$$ substrates implanted with Ge ions in comparatively shallow depth ($$sim$$100 nm) has been reported. In this paper, we report the photoluminescence (PL) properties of SiO$$_{2}$$ substrates implanted with Ge ions deeper than previous works ($$sim$$200 nm depth) in order to enlarge the spot size of the photonic crystals waveguides. Ge ions were implanted into an SiO$$_{2}$$ substrate with 350 keV, and the implantation amount was 1$$times$$10$$^{17}$$ ions/cm$$^{2}$$. PL peaks around a wavelength of 400 nm were observed. Stronger PL peaks were measured after annealing (900 $$^{circ}$$C), which confirmed an effect of improving the emission intensity by the annealing process. Though Ge ions were implanted more deeply than the earlier reported depth, similar results were confirmed. The expectation for a new light-emitting waveguide device that combines Ge-ion-implanted SiO$$_{2}$$ substrates with photonic crystal characteristics has risen.

46 (Records 1-20 displayed on this page)