Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 161

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Initiatives to address the lifetime improvement of HBC stripper foil for 3GeV synchrotron of J-PARC

Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.850 - 854, 2021/10

no abstracts in English

Journal Articles

Radiation damage mechanism in ceramics irradiated with swift heavy ions

Ishikawa, Norito; Taguchi, Tomitsugu*; Okubo, Nariaki

Shototsu, 18(3), p.43 - 55, 2021/05

Radiation damage mechanism in ceramics irradiated with swift heavy ions has been studied by using transmission electron microscopy (TEM). We introduce how the mechanisms are unveiled by our recent TEM studies.

Journal Articles

Radiation dose rate effects on the properties of a laser-induced breakdown spectroscopy system developed using a ceramics micro-laser for fiber-optic remote analysis

Tamura, Koji; Oba, Hironori; Saeki, Morihisa; Taguchi, Tomitsugu*; Lim, H. H.*; Taira, Takunori*; Wakaida, Ikuo

Journal of Nuclear Science and Technology, 58(4), p.405 - 415, 2021/04

 Times Cited Count:1 Percentile:39.17(Nuclear Science & Technology)

Radiation dose rate effects on the properties of a compact fiber-optic laser-induced breakdown spectroscopy (LIBS) system with a monolithic Nd:YAG/Cr:YAG composite ceramics were investigated for remote analysis in hazardous environment. To investigate radiation effects on the LIBS signal, properties related to the Nd:YAG laser operation such as oscillation threshold, output energy, oscillation timing, temporal pulse shape, and beam profile were measured as a function of the radiation dose rate from 0 to 10 kGy/hr in view of their influences to the signal. LIBS spectra of zirconium metal were measured under irradiation. Although signal intensity decreased considerably by irradiation, informative spectra were well obtained even at the maximum radiation dose rate. From the comparison of the LIBS-related parameters among the laser properties, signal reduction was mainly ascribed to the pulse energy reduction. Scintillation emission spectra were also measured from the ceramics during the irradiation, where the signal intensity increased linearly with the dose rate. The results show that the developed system.

Journal Articles

Analysis of J-HBC stripper foil for the J-PARC RCS

Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*

JPS Conference Proceedings (Internet), 33, p.011019_1 - 011019_7, 2021/03

The multi-turn charge-exchange H$$^{-}$$ beam injection scheme with stripper foils is one of the key techniques to achieve a MW-class high power proton beam. The J-PARC RCS adopts Hybrid type Boron-doped Carbon (HBC) stripper foil, which was developed in KEK to improve the lifetime. Indeed, the RCS user operation confirmed that HBC foil has the great advantage of a longer lifetime against high beam irradiation. To examine characteristics of the HBC foils, various beam studies were performed, such as the stripping efficiency measurement and long-term observation with an H$$^{-}$$ beam in the J-PARC RCS, foil analysis using RBS, EDR and PIXE methods, and SEM and TEM observation after the ion beam irradiation in Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) on National Institutes for Quantum and Radiological Science and Technology (QST). Recently, the deposition apparatus for the HBC foils from the KEK Tsukuba-site was relocated to the JAEA Tokai-site, and we started fabrication of new HBC foil in 2017. (The new one fabricated in JAEA we call J-HBC foil.) And, we continue investigations in TIARA with the J-HBC foils. Furthermore, in-depth researches by changing the process parameters of the foil deposition are carried on. Recent results suggest that the amount of the boron doped in the foil is more important parameter than the ratio of the discharge amount of carbon from cathode and anode electrodes. In this presentation, we will report the details of recent analysis of the J-HBC foil.

Journal Articles

Comprehensive understanding of hillocks and ion tracks in ceramics irradiated with swift heavy ions

Ishikawa, Norito; Taguchi, Tomitsugu*; Ogawa, Hiroaki

Quantum Beam Science (Internet), 4(4), p.43_1 - 43_14, 2020/12

Amorphizable ceramics were irradiated with 200 MeV Au ions, and the as-irradiated samples were observed by transmission electron microscopy (TEM). The ion track diameter and hillock diameter are similar for all the amorphizable ceramics. For SrTiO$$_{3}$$ and niobium-doped STO, 200 MeV Au ion irradiation and TEM observation were also performed. The ion track diameters in these materials are found to be markedly smaller than the hillock diameters. The ion tracks in these materials exhibit inhomogeneity, which is similar to that reported for non-amorphizable ceramics. On the other hand, the hillocks appear to be amorphous, and the amorphous feature is in contrast to the crystalline feature of hillocks observed in non-amorphizable ceramics. No marked difference is recognized between the nanostructures in STO and those in Nb-STO.

Journal Articles

TEM analysis of ion-tracks and hillocks produced by swift heavy ions of different velocities in Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$

Ishikawa, Norito; Taguchi, Tomitsugu*; Kitamura, Akane; Szenes, G.*; Toimil-Molares, M. E.*; Trautmann, C.*

Journal of Applied Physics, 127(5), p.055902_1 - 055902_7, 2020/02

 Times Cited Count:4 Percentile:68.88(Physics, Applied)

Hillock formation is one of the important aspects of radiation-induced modification of solid material. To our knowledge this is first result showing that the hillock formation in ceramics is affected by the velocity effect. The present result include Se-dependences of hillock dimensions based on precise measurement using TEM (transmission electron microscopy). The paper should be published to make researchers aware that hillock size is actually comparable to ion-track size in wide Se range. In addition, the results include important insight about the hillock formation mechanism of ceramics irradiated with swift heavy ions.

Journal Articles

In Situ Time-Resolved XAFS Studies on Laser-induced Particle Formation of Palladium Metal in an Aqueous/EtOH solution

Saeki, Morihisa*; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu*; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*

Journal of Physical Chemistry C, 123(1), p.817 - 824, 2019/01

 Times Cited Count:6 Percentile:37.24(Chemistry, Physical)

Reaction kinetics of laser-induced particle formation in an aqueous solution of PdCl$$_{4}$$$$^{2-}$$ was investigated by transmission electron microscope (TEM) and dispersive X-ray absorption fine structure (DXAFS). The Pd particle was generated by irradiation of nanosecond pulsed 266-nm laser. The TEM observation showed dependence of the particle size on the laser fluence and promotion of the particle growth by irradiation of high-fluence laser. The DXAFS data give us the Pd$$^{2+}$$ concentration. Temporal changes of the Pd$$^{2+}$$ concentration analyzed based on Finke-Watzky two step mechanism. The analysis elucidates that the laser photon contributes to the reduction of the PdCl$$_{4}$$$$^{2-}$$ ion by the one-photon process and to the autocatalytic growth of the Pd particles by the multi-photon process.

Journal Articles

X-ray absorption study of platinum nanoparticles on an ion-irradiated carbon support

Kakitani, Kenta*; Kimata, Tetsuya*; Yamaki, Tetsuya*; Yamamoto, Shunya*; Matsumura, Daiju; Taguchi, Tomitsugu*; Terai, Takayuki*

Radiation Physics and Chemistry, 153, p.152 - 155, 2018/12

 Times Cited Count:1 Percentile:17.98(Chemistry, Physical)

Journal Articles

Local disorder in proton conductor BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ analyzed by neutron diffraction/ atomic pair distribution function

Igawa, Naoki; Kodama, Katsuaki; Taguchi, Tomitsugu*; Yoshida, Yukihiko*; Matsukawa, Takeshi*; Hoshikawa, Akinori*; Ishigaki, Toru*

Transactions of the Materials Research Society of Japan, 43(6), p.329 - 332, 2018/12

For the understanding of the crystal structural effect on the electrical properties, the local disorder in BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ which is one of the excellent proton conductors for solid oxide fuel cells was estimated by using the Atomic Pair Distribution Function (PDF) analysis method with the neutron diffraction. The local structure is almost the same as the average structure which was estimated by the Rietveld analysis using the cubic crystal structure (space group, $${it Pm}$$$$overline{3}$$$${it m}$$) in the atomic distance range of ${it r}$ $$>$$ 6${AA}$. The PDF profile was fitted better using the tetragonal crystal structure with the space group of ${it P}$4/${it mmm}$ than those with $${it Pm}$$$$overline{3}$$$${it m}$$ in the range ${it r}$ $$<$$ 6${AA}$. Those results indicate the presence of the local disorder in the lattice. In this work, the relationship between the average and local structures of BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ will be discussed.

Journal Articles

Influence of gamma-ray irradiation on mechanical property of YSZ for oxygen sensors in ADS

Okubo, Nariaki; Okuno, Yasuki; Kitamura, Akane; Taguchi, Tomitsugu*

Nuclear Instruments and Methods in Physics Research B, 435, p.198 - 202, 2018/11

 Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)

Accelerator driven system (ADS) adopts the lead-bismuth eutectic (LBE) as both coolant and spallation target. The oxygen concentration control is one of the most important technical developments. Estimation of durability under gamma-ray irradiation for the oxygen sensor is necessary for the integrity evaluation of ADS components. The Zirconia added by Yttria (YSZ) is the main element in oxygen sensor. Effect of gamma-ray irradiation on the mechanical property and structural change for three types of YSZ with 3, 6, 8 mol% Yttria was evaluated by using 4 points bend test, XRD, SEM and Raman spectroscope. The gamma-ray irradiations were conducted at 1 and 2 kGy/h, which corresponded to the LBE activity after 1 year ADS operation. In the cases of 8Y and 6Y, degradation of strength was not measured and the fracture surface did not change the morphology. In the case of 3Y, however, the strength did not change but phase transformation from tetragonal to monoclinic crystal structure was observed in XRD results, depending on the irradiation dose. This implies that the gamma-ray irradiation causes the phase transformation in 3Y-YSZ.

Journal Articles

Hillocks created for amorphizable and non-amorphizable ceramics irradiated with swift heavy ions; TEM study

Ishikawa, Norito; Taguchi, Tomitsugu*; Okubo, Nariaki

Nanotechnology, 28(44), p.445708_1 - 445708_11, 2017/11

 Times Cited Count:12 Percentile:63.51(Nanoscience & Nanotechnology)

TEM method is applied to Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$ (YIG) and three fluorides (CaF$$_{2}$$, SrF$$_{2}$$ and BaF$$_{2}$$) for observing hillocks. For YIG which is one of the amorphizable materials, hillocks are found to have amorphous feature which is consistent with amorphous feature of ion-tracks. For the fluorides, it is found that the hillocks do not exhibit amorphous feature, and they are composed of nano-crystallites. It is found for the first time that for YIG the hillock diameter is comparable to the ion-track diameter, whereas for the fluorides it is always larger than the ion-track diameter. The results indicate that recrystallization after transient melting plays an important role for formation of hillocks and ion-tracks in fluorides.

Journal Articles

Study on laser-induced particle formation of palladium ion by time-resolved X-ray spectroscopy

Saeki, Morihisa*; Taguchi, Tomitsugu*; Oba, Hironori*; Matsumura, Daiju; Tsuji, Takuya; Yomogida, Takumi

Denki Gakkai Kenkyukai Shiryo, Denshi Zairyo Kenkyukai (EFM-17-010$$sim$$021), p.15 - 18, 2017/09

Irradiation of nanosecond pulsed UV laser into a solution of palladium ion leads to formation of palladium particles with sub-micron size particles by time-resolved X-ray absorption spectroscopy.

Journal Articles

Encapsulation of cesium from contaminated water with highly selective facial organic-inorganic mesoporous hybrid adsorbent

Awual, M. R.; Miyazaki, Yuji; Taguchi, Tomitsugu; Shiwaku, Hideaki; Yaita, Tsuyoshi

Chemical Engineering Journal, 291, p.128 - 137, 2016/05

 Times Cited Count:166 Percentile:99.43(Engineering, Environmental)

Journal Articles

A Reliable hybrid adsorbent for efficient radioactive cesium accumulation from contaminated wastewater

Awual, M. R.; Yaita, Tsuyoshi; Miyazaki, Yuji; Matsumura, Daiju; Shiwaku, Hideaki; Taguchi, Tomitsugu

Scientific Reports (Internet), 6, p.19937_1 - 19937_10, 2016/01

AA2015-0789.pdf:1.31MB

 Times Cited Count:132 Percentile:98.16(Multidisciplinary Sciences)

Journal Articles

Synthesis of heterostructured SiC and C-SiC nanotubes by ion irradiation-induced changes in crystallinity

Taguchi, Tomitsugu; Yamamoto, Shunya; Kodama, Katsuaki; Asaoka, Hidehito

Carbon, 95, p.279 - 285, 2015/12

 Times Cited Count:9 Percentile:36.8(Chemistry, Physical)

Amorphous SiC nanotubes are successfully synthesized by 340 keV Si$$^{+}$$ ions irradiation of polycrystalline SiC nanotubes for the first time. A polycrystalline/amorphous heterostructure SiC nanotube, in which polycrystalline SiC and amorphous SiC coexist in the same nanotube, is also synthesized by ions irradiation with a mask in front of polycrystalline SiC nanotube. According to electron energy loss spectroscopy evaluation, the plasmon energies of SiC nanotube change rapidly at the interface between polycrystalline and amorphous regions. The volume swelling by amorphization evaluated from the differences of plasmon energies is approximately 5.0%. This result reveals that the further relaxed amorphous SiC nanotubes with higher density can be produced. The graphitic shells in carbon layer of C-SiC nanotube gradually bend to the radial direction of nanotube by the ion irradiation. Since the graphite (002) spots in the selected area electron diffraction pattern are clearly observed even after the ion irradiation, the carbon layer in C-SiC nanotube has certain crystallinity. Moreover, the new multi-walled carbon nanotube with the graphitic shells completely parallel to the radial direction of nanotube is also produced inside the amorphous SiC tubular layer in the case of C-SiC nanotube with large caliber.

Journal Articles

Experimental evidence of crystalline hillocks created by irradiation of CeO$$_{2}$$ with swift heavy ions; TEM study

Ishikawa, Norito; Okubo, Nariaki; Taguchi, Tomitsugu

Nanotechnology, 26(35), p.355701_1 - 355701_8, 2015/09

 Times Cited Count:18 Percentile:68.15(Nanoscience & Nanotechnology)

In this study, CeO$$_{2}$$ was irradiated with 200 MeV Au ions at oblique incidence. Observation of as-irradiated samples by transmission electron microscope (TEM) shows that hillocks are created not only at the wide surfaces, but also at the crack faces of the thin samples. Since the hillocks created at the crack faces can be imaged by TEM, their shape and crystallographic features can be revealed. From the images of hillocks created at the crack faces, many of the hillocks are found to be spherical. We present a first experimental evidence that hillocks created for CeO$$_{2}$$ irradiated with swift heavy ions have a crystal structure whose lattice spacing and orientation coincide with those of the matrix. The mechanism of spherical crystalline hillock formation is discussed based on the present results.

Journal Articles

Crystal structure and electron density distribution analyses of Nd$$_{x}$$Ce$$_{1-x}$$O$$_{2-delta}$$ for electrolyte by Rietveld/ maximum entropy method

Taguchi, Tomitsugu; Igawa, Naoki; Birumachi, Atsushi; Asaoka, Hidehito; Miwa, Shuhei; Osaka, Masahiko

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.339 - 342, 2015/06

Rare-earth doped ceria exhibits both ionic and electronic conductions, and those ceria with higher ratio of ionic conduction against electronic conduction is used as a solid electrolyte for solid oxide fuel cells. The electron density distributions in crystals are closely related to the electron diffusing pathway which affects the electronic conduction. In this study, we investigated the electron density distribution of doped ceria as a function of the content of Nd$$_{2}$$O$$_{3}$$-dopant to deduce the ratio of the electronic to ionic conduction. The crystal structure was refined with the space group, ${it Fm}$-3${it m}$, which is the same as undoped ceria. Ce and Nd ions randomly occupied the 4${it a}$ site and O ion the 8${it c}$ site. The electron conduction pathway was distributed through the 4${it a}$-8${it c}$ and 8${it c}$-8${it c}$ sites. The relationship between crystal structural change and electron density distribution as a function of the content of Nd$$_{2}$$O$$_{3}$$ dopant will be discussed.

Journal Articles

Tailoring crystallinity and configuration of silica nanotubes by electron irradiation

Taguchi, Tomitsugu; Yamaguchi, Kenji

Nuclear Instruments and Methods in Physics Research B, 350, p.1 - 5, 2015/05

 Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)

SiO$$_{2}$$ nanotubes show potential in applications such as nanoscale electronic and optical devices, bioseparation, biocatalysis, and nanomedicine. As-grown SiO$$_{2}$$ nanotubes in the previous studies always have an amorphous wall, and here we demonstrate the successful synthesis of single-crystal nanotubes for the first time by the heat treatment of SiC nanotubes at 1300 $$^{circ}$$C for 10 h under low-vacuum conditions. According to TEM observations, the single-crystal SiO$$_{2}$$ was $$alpha$$-cristobalite. We also demonstrate that single-crystal SiO$$_{2}$$ nanotubes can be transformed into amorphous SiO$$_{2}$$ nanotubes by electron beam irradiation. Moreover, we synthesized a crystalline/amorphous SiO$$_{2}$$ composite nanotube, in which crystalline and amorphous SiO$$_{2}$$ coexisted in different localized regions. In addition, for biomedical applications such as drug delivery systems, controlling the configuration of the open end, the diameter, and capsulation of SiO$$_{2}$$ nanotubes is crucial. We can also obturate, capsulate, and cut a SiO$$_{2}$$ nanotube, as well as modify the inner diameter of the nanotube at a specific, nanometer-sized region using the focused electron beam irradiation technique.

Journal Articles

Nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ analyzed by combination of Rietveld/ maximum entropy method

Igawa, Naoki; Kodama, Katsuaki; Birumachi, Atsushi; Taguchi, Tomitsugu

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.247 - 252, 2015/05

The nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ which is one of the primitive cathode materials for secondary Li-ion batteries, were analyzed by applying Rietveld refinement and MEM to neutron and X-ray diffraction data, to estimate the Li diffusing pathway. The crystal structure of LiMn$$_{2}$$O$$_{4}$$ could be refined with the space group, ${it Fd}$-3${it m}$ in the temperature range from 240 to 573 K. The structure was transformed to ${it Fddd}$ below 240 K. The isotropic thermal displacement parameter of Li was proportional to the temperature excluding 240 to 300 K. According to the MEM analyses it was indicated that the Li ions diffuse through 8${it b}$ and 16${it e}$ around 300 K.

Journal Articles

Wet separation between palladium(II) and molybdenum(IV) ions by using laser-induced particle formation; Enhancement of recovery efficiency of palladium by laser condition

Saeki, Morihisa; Taguchi, Tomitsugu; Nakashima, Nobuaki*; Oba, Hironori

Journal of Photochemistry and Photobiology A; Chemistry, 299, p.189 - 193, 2015/02

 Times Cited Count:7 Percentile:21.94(Chemistry, Physical)

161 (Records 1-20 displayed on this page)