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Journal Articles

Analysis of ion-irradiation induced lattice expansion and ferromagnetic state in CeO$$_{2}$$ by using Poisson distribution function

Yamamoto, Yuki*; Ishikawa, Norito; Hori, Fuminobu*; Iwase, Akihiro*

Quantum Beam Science (Internet), 4(3), p.26_1 - 26_13, 2020/09

The lattice constant and the magnetic state of CeO$$_{2}$$ are modified by the irradiation with 200 MeV Xe ions. Under the assumption that these modifications are induced in the narrow one-dimensional region (the ion track) along the ion beam path, the dependence of the lattice constant and the saturation magnetization of CeO$$_{2}$$ on the Xe ion fluence can be analyzed by using the Poisson distribution function. The analysis reveals that the lattice constant inside the ion track, which is larger than outside the ion track is not affected by the overlapping of the ion track. The present result implies that the Poisson distribution function is useful for describing the effect of ion track overlapping on the ion irradiation induced ferromagnetic state in CeO$$_{2}$$.

Journal Articles

Ion species/energy dependence of irradiation-induced lattice structure transformation and surface hardness of Ni$$_{3}$$Nb and Ni$$_{3}$$Ta intermetallic compounds

Kojima, Hiroshi*; Kaneno, Yasuyuki*; Ochi, Masaaki*; Semboshi, Satoshi*; Hori, Fuminobu*; Saito, Yuichi*; Ishikawa, Norito; Okamoto, Yoshihiro; Iwase, Akihiro*

Materials Transactions, 58(5), p.739 - 748, 2017/05

 Times Cited Count:4 Percentile:31.31(Materials Science, Multidisciplinary)

Bulk samples of Ni$$_{3}$$Nb and Ni$$_{3}$$Ta intermetallic compounds were irradiated with 16 MeV Au, 4.5 MeV Ni, 4.5 MeV Al, 200 MeV Xe and 1.0 MeV He ions, and the change in near-surface lattice structure was investigated by means of the grazing incidence X-ray diffraction (GIXD)and EXAFS. The Ni$$_{3}$$Nb and Ni$$_{3}$$Ta lattice structures transform from the ordered structures (orthorhombic and monoclinic structures for Ni$$_{3}$$Nb and Ni$$_{3}$$Ta, respectively) to the amorphous state by the Au, Ni, Al and Xe ion irradiations. Irrespective of such heavy ion species or energies, the lattice structure transformation to the amorphous state almost correlate with the density of energy deposited through elastic collisions.

Journal Articles

Lattice structure transformation and change in surface hardness of Ni$$_3$$Nb and Ni$$_3$$Ta intermetallic compounds induced by energetic ion beam irradiation

Kojima, Hiroshi*; Yoshizaki, Hiroaki*; Kaneno, Yasuyuki*; Semboshi, Satoshi*; Hori, Fuminobu*; Saito, Yuichi; Okamoto, Yoshihiro; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 372, p.72 - 77, 2016/04

 Times Cited Count:8 Percentile:71.87(Instruments & Instrumentation)

Ni$$_3$$Nb and Ni$$_3$$Ta intermetallic compounds, which show the complicated lattice structures were irradiated with 16 MeV Au$$^{5+}$$ ions at room temperature. The X-ray diffraction measurement revealed that the lattice structure of these intermetallic compounds changed from the ordered structures to the amorphous state by the ion irradiation. The irradiation-induced amorphization caused the increase in Vickers hardness. The result was compared with our previous results for Ni$$_3$$Al and Ni$$_3$$V, and was discussed in terms of the intrinsic lattice structures of the samples.

Journal Articles

Hardness modification of Al-Mg-Si alloy by using energetic ion beam irradiation

Ueyama, Daichi*; Saito, Yuichi; Ishikawa, Norito; Omura, Takahito*; Semboshi, Satoshi*; Hori, Fuminobu*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 351, p.1 - 5, 2015/05

 Times Cited Count:4 Percentile:40.75(Instruments & Instrumentation)

Journal Articles

Hardening induced by energetic electron beam for Cu-Ti alloys

Ueyama, Daichi*; Semboshi, Satoshi*; Saito, Yuichi; Ishikawa, Norito; Nishida, Kenji*; Soneda, Naoki*; Hori, Fuminobu*; Iwase, Akihiro*

Japanese Journal of Applied Physics, 53(5S1), p.05FC04_1 - 05FC04_5, 2014/05

 Times Cited Count:5 Percentile:26.55(Physics, Applied)

In our previous research, it was found that the hardness of Cu-Ti alloy increased by energetic heavy ion irradiation at room temperature. In the conference, we will show the result of electron beam irradiation on the hardness of Cu-Ti alloys. We used CuTi sheets with the dimension of 10 $$times$$ 10 $$times$$ 0.250 mm$$^{3}$$. The specimens were irradiated at 473 K and 523 K with 2 MeV electrons. For comparison, we thermally aged some specimens at the same temperatures as that for the irradiation. The electron fluence of 8.0 $$times$$ 10$$^{17}$$/cm$$^{2}$$ corresponds to the processing time of about 10 h. As a result, the thermal aging for 10 h increases the hardness by 5 or less, which is much smaller than that by the irradiation (about 20). The hardness of the reverse side of irradiated surface is almost the same as that of the irradiated surface. The present result implies that energetic electron irradiation can be a useful tool for controlling the hardness of the "bulk" Cu-Ti alloy.

Journal Articles

Irradiation effect of swift heavy ion for Zr$$_{50}$$Cu$$_{40}$$Al$$_{10}$$ bulk glassy alloy

Onodera, Naoto*; Ishii, Akito*; Ishii, Koji*; Iwase, Akihiro*; Yokoyama, Yoshihiko*; Saito, Yuichi; Ishikawa, Norito; Yabuuchi, Atsushi*; Hori, Fuminobu*

Nuclear Instruments and Methods in Physics Research B, 314, p.122 - 124, 2013/11

 Times Cited Count:3 Percentile:29.69(Instruments & Instrumentation)

It has been reported that heavy ion irradiation causes softening in some cases of Zr-based bulk metallic glass alloys. However, the fundamental mechanisms of such softening have not been clarified yet. In this study, Zr$$_{50}$$Cu$$_{40}$$Al$$_{10}$$ bulk glassy alloys were irradiated with heavy ions of 10 MeV I at room temperature. Positron annihilation measurements have performed before and after irradiation to investigate changes in free volume. We discuss the relationship between the energy loss and local open volume change after 10 MeV I irradiation compared with those obtained for 200 MeV Xe and 5 MeV Al. The energy loss analysis in ion irradiation for the positron lifetime has revealed that the decreasing trend of positron lifetime is well expressed as a function of total electronic energy deposition rather than total elastic energy deposition. It means that the positron lifetime change by the irradiation has a relationship with the inelastic collisions with electrons during heavy ion irradiation.

Journal Articles

Change in magnetic properties induced by swift heavy ion irradiation in CeO$$_{2}$$

Shimizu, Hirotaka*; Kosugi, Shinya*; Tahara, Yuki*; Yasunaga, Kazufumi*; Kaneta, Yasunori*; Ishikawa, Norito; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 286, p.291 - 294, 2012/09

 Times Cited Count:25 Percentile:89.76(Instruments & Instrumentation)

We have studied the magnetic properties of pure CeO$$_{2}$$ irradiated with swift heavy ions. Experiment a results showed that the ferromagnetism was induced even at room temperature by 200 MeV Xe ion irradiation. The value of saturation magnetization, Ms, systematically changes as a function of ion-fluence. The X-ray diffraction (XRD) spectra show that the lattice constant of CeO$$_{2}$$ increases with increasing ion-fluence. This result and our previous XPS result show that the ion-irradiation produced oxygen vacancies. The present study implies that the ferromagnetic behavior of the ion-irradiated CeO$$_{2}$$ is attributed to the magnetic moments of localized 4f electrons on Ce$$^{3+}$$ atoms, which are related to oxygen vacancies.

Journal Articles

Study on effects of energetic ion irradiation in Gd$$_{2}$$O$$_{3}$$-doped CeO$$_{2}$$ by means of synchrotron radiation X-ray spectroscopy

Tahara, Yuki*; Shimizu, Hirotaka*; Ishikawa, Norito; Okamoto, Yoshihiro; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 277, p.53 - 57, 2012/04

In this study, to simulate such an environment, Gd$$_{2}$$O$$_{3}$$-doped CeO$$_{2}$$ samples were irradiated with 200 MeV Xe$$^{14+}$$ ions at room temperature using an ion beam accelerator at JAEA-Tokai. As CeO$$_{2}$$ has the same fluorite structure as that of UO$$_{2}$$ and several properties of CeO$$_{2}$$ are similar to UO$$_{2}$$, in this study CeO$$_{2}$$ was used as a simulation material of UO$$_{2}$$. To study the effects of the ion irradiation on Gd$$_{2}$$O$$_{3}$$-doped CeO$$_{2}$$, extended X-ray absorption fine structure (EXAFS) and X-ray photoelectron spectroscopy (XPS) were used at the Photon Factory of High Energy Accelerator Research Organization (KEK) as well as conventional X-ray diffraction (XRD) measurement. The EXAFS and XRD spectra show that the effects of the ion irradiation are more pronounced for higher amount of Gd$$_{2}$$O$$_{3}$$ dopant.

Journal Articles

Study on effects of energetic ion irradiation in Gd$$_2$$O$$_3$$-doped CeO$$_2$$ by means of synchrotron radiation X-ray spectroscopy

Tahara, Yuki*; Shimizu, Hirotaka*; Ishikawa, Norito; Okamoto, Yoshihiro; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 277, p.53 - 57, 2012/04

 Times Cited Count:8 Percentile:58.08(Instruments & Instrumentation)

To study the effects of Gd$$_2$$O$$_3$$-doping and the irradiation with high energy fission products in the nuclear fuels (UO$$_2$$), Gd$$_2$$O$$_3$$-doped CeO$$_2$$ pellets were irradiated with 200 MeV Xe$$^{14+}$$ ions. Effects of Gd$$_2$$O$$_3$$-doping and the ion irradiation were estimated by using Extended X-ray Absorption Fine Structure (EXAFS) measurement. The interatomic distances between each Ce and the first nearest O atoms, and Ce and the second nearest Ce atoms increase by the irradiation and the effect of the ion irradiation on the atomic distances is more pronounced for higher amounts of dopant. The Debye-Waller factors for Ce-O and Ce-Ce pairs increase with increasing the amount of Gd$$_2$$O$$_3$$ dopant. These results suggest that the lattice binding energy is weakened by Gd$$_2$$O$$_3$$-doping. The Debye-Waller factors increase also by the irradiation. The effect of ion irradiation on the Debye-Waller factors, however, becomes smaller for higher amounts of dopant.

Journal Articles

Hardness modification of aluminum-alloys by means of energetic ion irradiation and subsequent thermal aging

Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.

Nuclear Instruments and Methods in Physics Research B, 272, p.49 - 52, 2012/02

 Times Cited Count:7 Percentile:53.66(Instruments & Instrumentation)

Journal Articles

Study on Au cluster ion irradiation effects for Fz-Si single crystal by using slow positron beam

Hori, Fuminobu*; Kawasuso, Atsuo; Saito, Yuichi; Iwase, Akihiro*

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 154, 2012/01

Journal Articles

Study on defects in H$$^+$$ ion implanted B2 type Fe-Al alloy using slow positron beam

Komagata, Eiichi*; Kawasuso, Atsuo; Yabuuchi, Atsushi*; Maekawa, Masaki; Batchuluun, C.*; Yasuda, Keisuke*; Ishigami, Ryoya*; Kume, Kyo*; Iwase, Akihiro*; Hori, Fuminobu*

Physics Procedia, 35, p.75 - 79, 2012/00

 Times Cited Count:2 Percentile:64.41

Fe48-at.% Al alloy were implanted with 50 keV H$$^+$$ ions to the fluence of 3$$times$$10$$^{16}$$ and 1$$times$$10$$^{18}$$ /cm$$^2$$ at room temperature. Positron annihilation Doppler broadening and lifetime measurements for these alloys have been carried out using slow positron beam apparatus with an energy range of 0.2 to 30.2 keV. The positron annihilation S-parameter decreased by H$$^+$$ ion irradiation. Also the positron lifetimes for hydrogen deposited region in the alloy decreased by the irradiation. These results show that implanted H atoms were trapped by vacancy type defects.

Journal Articles

Study on effects of swift heavy ion irradiation on the crystal structure in CeO$$_{2}$$ doped with Gd$$_{2}$$O$$_{3}$$

Tahara, Yuki*; Zhu, B.-L.*; Kosugi, Shinya*; Ishikawa, Norito; Okamoto, Yoshihiro; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 269(9), p.886 - 889, 2011/05

 Times Cited Count:14 Percentile:76.2(Instruments & Instrumentation)

CeO$$_{2}$$ pellets doped with Gd$$_{2}$$O$$_{3}$$ were irradiated with 200-MeV Xe ions, and the effects of Gd$$_{2}$$O$$_{3}$$-doping and irradiation on the lattice structure were measured using XRD and EXAFS. The lattice constant decreases with increasing Gd$$_{2}$$O$$_{3}$$-doping and the local structure near the Gd atoms is more disordered with increasing amounts of Gd$$_{2}$$O$$_{3}$$-dopant. The irradiation induces an expansion of the lattice and disordering of the atomic arrangement around Gd atoms. The effect of high-energy ion irradiation becomes more pronounced with increasing amounts of Gd$$_{2}$$O$$_{3}$$-dopant.

Journal Articles

Effect of high temperature annealing on ferromagnetism induced by energetic ion irradiation in FeRh alloy

Kosugi, Shinya*; Fujita, Naoki*; Matsui, Toshiyuki*; Hori, Fuminobu*; Saito, Yuichi; Ishikawa, Norito; Okamoto, Yoshihiro; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 269(9), p.869 - 872, 2011/05

 Times Cited Count:9 Percentile:62.21(Instruments & Instrumentation)

Effects of thermal annealing on ion-irradiation induced ferromagnetism of FeRh bulk alloy and the related structural change were investigated by means of superconducting quantum interference device (SQUID) and extended X-ray absorption fine structure (EXAFS), respectively. Depending on the annealing temperature from 100 to 500 $$^{circ}$$C, the magnetization induced by 10 MeV iodine ion irradiation and the lattice structure of the alloy were remarkably changed. After 500 $$^{circ}$$C annealing, the magnetization and the lattice ordering of the alloy become similar to the states before the irradiation. The experimental result indicates that the thermal relaxation of irradiation-induced atomic disordering dominates the magnetic state of ion-irradiated FeRh alloy.

Journal Articles

Study on ion-irradiation-induced ferromagnetism in FeRh intermetallic compound by means of magnetic Compton scattering

Kosugi, Shinya*; Matsui, Toshiyuki*; Ishikawa, Norito; Ito, Masayoshi*; Sakurai, Yoshiharu*; Aiko, Kazuma*; Shimizu, Hirotaka*; Tahara, Yuki*; Hori, Fuminobu*; Iwase, Akihiro*

Journal of Applied Physics, 109(7), p.07B737_1 - 07B737_3, 2011/04

 Times Cited Count:7 Percentile:33.93(Physics, Applied)

The magnetic Compton profiles of FeRh intermetallic compound were measured to study the ferromagnetism induced by 200 MeV Xe ion irradiation. The magnetic effect at 50 K increases with increasing the ion-fluence. The analysis of the experimental result revealed that the values of spin moment induced by the irradiation were close to the values of magnetization obtained by a superconducting quantum interference device magnetometer, suggesting that the ion irradiation mainly induces the spin magnetic moment.

Journal Articles

Determination of threshold energies for displacements of Fe and Rh atoms in Fe-50 at.%Rh intermetallic compound by using energetic electron irradiation at low temperatures

Kosugi, Shinya*; Ishikawa, Norito; Saito, Yuichi; Hori, Fuminobu*; Iwase, Akihiro*

Journal of Nuclear Materials, 411(1-3), p.171 - 173, 2011/04

 Times Cited Count:2 Percentile:20.43(Materials Science, Multidisciplinary)

Changes in electrical resistivity induced by irradiation with energetic electrons were measured for Fe-50 at.%Rh alloy as a function of electron energy in the range from 0.5 to 2.0 MeV. The irradiation was carried out below 20 K and the resistivity was measured at 10 K. The electron energy dependence of the resistivity change rate was analysed by using a simple displacement theory, and the average threshold energies for atomic displacements, $$E$$$$_{d}$$, were determined as 30 eV for Fe and 45 eV for Rh.

Journal Articles

Hardening of Al-Cu-Mg alloy by energetic ion irradiation

Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.

Journal of Nuclear Materials, 408(2), p.201 - 204, 2011/01

 Times Cited Count:10 Percentile:65.84(Materials Science, Multidisciplinary)

Journal Articles

A Study of defects in electron- and ion-irradiated ZrCuAl bulk glassy alloy using positron annihilation techniques

Hori, Fuminobu*; Onodera, Naoto*; Fukumoto, Yuka*; Ishii, Akito*; Iwase, Akihiro*; Kawasuso, Atsuo; Yabuuchi, Atsushi; Maekawa, Masaki; Yokoyama, Yoshihiko*

Journal of Physics; Conference Series, 262, p.012025_1 - 012025_4, 2011/01

 Times Cited Count:4 Percentile:83.4

Free volume changes in Zr$$_{50}$$Cu$$_{40}$$Al$$_{10}$$ bulk glassy alloys irradiated by 200 and 2.5 MeV Xe ions, 180 keV He ions, and 2 MeV electrons were investigated at room temperature using positron annihilation techniques. X-ray diffraction revealed that no crystallization took place in any of the irradiated sample. The positron lifetime increased only after electron and 180 keV He irradiation. This indicates that the radiation has increased the open volume size (free volume). On the other hand, the positron lifetime was decreased by irradiation with heavy Xe-ions at either energy of 2.5 or 200 MeV. It is conceivable that the difference in behavior can be attributed to the difference in displacements per radiation particle (dpp), because the dpp estimated for 2 MeV electrons and 180 keV He ions is three or more orders of magnitude less than that for heavy Xe ions. We found that the radiation effect in ZrCuAl bulk glassy alloy is dependent on the displacement per radiation particle.

Journal Articles

Free volume in Zr-based bulk glassy alloys studied by positron annihilation techniques

Ishii, Akito*; Iwase, Akihiro*; Yokoyama, Yoshihiko*; Konno, Toyohiko*; Kawasuso, Atsuo; Yabuuchi, Atsushi; Maekawa, Masaki; Hori, Fuminobu*

Journal of Physics; Conference Series, 225, p.012020_1 - 012020_6, 2010/06

 Times Cited Count:5 Percentile:87.1

To reveal the relationship between mechanical properties and microscopic structure of Zr-based amorphous metals, we performed positron annihilation measurements on specimens with different Zr contents. Although the positron lifetimes were nearly the same for all the specimens, the Doppler broadening of annihilation radiation spectra were significantly different for the specimens at and above the eutectic point. This indicates that both the structure and composition of free volumes depend on the Zr-content.

Journal Articles

Characterization of swift heavy ion-induced defects in Fe-Rh alloy by using positron beam technique

Hori, Fuminobu*; Fukuzumi, Masafumi*; Kawasuso, Atsuo; Zushi, Yoshihiro*; Chimi, Yasuhiro; Ishikawa, Norito; Iwase, Akihiro*

Physica Status Solidi (C), 4(10), p.3530 - 3533, 2007/09

 Times Cited Count:0 Percentile:0.07

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33 (Records 1-20 displayed on this page)