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Journal Articles

Sputter etching effect of the substrate on the microstructure of $$beta$$-FeSi$$_{2}$$ thin film prepared by ion beam sputter deposition method

Sasase, Masato*; Shimura, Kenichiro*; Yamaguchi, Kenji; Yamamoto, Hiroyuki; Shamoto, Shinichi; Hojo, Kiichi

Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.186 - 189, 2007/04

 Times Cited Count:5 Percentile:42.39(Instruments & Instrumentation)

Beta iron disilicide ($$beta$$-FeSi$$_{2}$$) is one of the candidate materials for a compound semiconductor. We have employed ion beam sputter deposition method to grow highly oriented $$beta$$-FeSi$$_{2}$$ film on a single crystal Si(100) substrate. In the present study, sputter etching effect of the substrate is investigated by the cross-sectional transmission electron microscope (TEM) observation in order to observe nanostructural changes as a function of Ne$$^{+}$$ energy. The observed TEM images show that the 1 keV sputtering provides uniform films with few defects and smooth interface. The number of the produced defects rapidly increases with the energy. The obtained $$beta$$-FeSi$$_{2}$$ tends to form small grains at the higher energy. Quite rough surface is also observed in this condition. Higher energies produce excessive amount of damages for the substrate to form epitaxially grown film. These results imply that a certain fluence is required for better quality of the deposited film.

Journal Articles

Modification of magnetic properties in Fe-Ni alloy thin films induced by energetic ion irradiation

Chimi, Yasuhiro; Ishikawa, Norito; Iwase, Akihiro*; Ono, Fumihisa*

Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.388 - 391, 2007/04

 Times Cited Count:8 Percentile:55.22(Instruments & Instrumentation)

We have already found that high-energy heavy ion irradiation modifies magnetic properties in Fe-Ni invar alloys, i.e. that the Curie temperature, $$T_{rm c}$$, increases by the irradiation. In the present paper, in order to clarify the mechanism of the modification, we investigate a dominant irradiation parameter for the modification. Specimens of Fe-Ni and Fe-Ni-Mn alloy thin films ($$sim$$500 nm in thickness) are prepared on MgO(100) single crystal substrates by rf magnetron sputtering. The specimens are irradiated at room temperature with several kinds of ions in the energy and mass ranges of 1.0-200 MeV and $$^{1}$$H-$$^{197}$$Au. A large increase in $$T_{rm c}$$ is observed for comparatively low-energy ion irradiation. This result suggests that the dominant process for the modification is the elastic interaction between incident ions and target atoms. The dependence on ion energy and fluence of the increase in $$T_{rm c}$$ gives information on a dominant irradiation parameter.

Journal Articles

Local modification of hardness in FeCu alloys by using swift heavy ion irradiation

Nakagawa, Sho*; Hori, Fuminobu*; Chimi, Yasuhiro; Ishikawa, Norito; Kitagawa, Michiharu*; Oshima, Ryuichiro*; Tobita, Toru; Taniguchi, Ryoichi*; Suzuki, Masahide; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.397 - 401, 2007/04

 Times Cited Count:4 Percentile:36.92(Instruments & Instrumentation)

Supersaturated Fe-1.2wt.%Cu alloys were irradiated with 200-MeV Xe and 200-MeV Au ions at elevated temperatures. To make an irradiated region and an unirradiated region in a specimen, a masking plate was put on the specimen during the irradiation. After the irradiation, the hardness was measured by using a conventional microhardness tester or a nano-indenter. We have found that the hardness only in irradiated region increases by the irradiation. The boundary of irradiated and unirradiated regions can be clearly identified by the difference in hardness. The present result implies that swift heavy ion irradiation can be used for the local modification of hardness in supersaturated alloys.

Journal Articles

Modification of Fe-Pd invar alloys by high-energy heavy ions

Ono, Fumihisa*; Chimi, Yasuhiro; Ishikawa, Norito; Kanamitsu, Hiroaki*; Matsushima, Yasushi*; Iwase, Akihiro*; Kambara, Tadashi*

Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.402 - 405, 2007/04

 Times Cited Count:5 Percentile:42.39(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Ion beam effects on electrical characteristics of proton conductive polymer

Nagata, Shinji*; Konishi, Yoshitada*; Tsuchiya, Bun*; To, Kentaro*; Yamamoto, Shunya; Takahiro, Katsumi*; Shikama, Tatsuo*

Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.519 - 522, 2007/04

 Times Cited Count:7 Percentile:51.64(Instruments & Instrumentation)

Effects of MeV ion irradiation on electrical characteristics of perfluorosulphonic polymer membrane have been studied. The DC electrical conductivity in dry condition increased of three orders of magnitude as a consequence of irradiation with MeV region H and He ion irradiation at a fluence of 2 $$times$$ 10$$^{13}$$ ions/cm$$^{2}$$. The optical absorption in the ultra-violet region increased in the ion irradiated membrane due to the formation of fluorocarbon and peroxy radicals. The ion irradiation may form fluorocarbon and peroxy compounds and improve the transport property of protons in the membrane.

Journal Articles

Ion irradiation effects on amorphization and thermal crystallization in Zr-Al-Ni-Cu alloys

Nagata, Shinji*; Higashi, Seijiro*; Tsuchiya, Bun*; To, Kentaro*; Shikama, Tatsuo*; Takahiro, Katsumi*; Ozaki, Koichi*; Kawatsura, Kiyoshi*; Yamamoto, Shunya; Inoue, Aichi

Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.420 - 423, 2007/04

 Times Cited Count:16 Percentile:74.96(Instruments & Instrumentation)

Structural modification and primary precipitates in the Zr$$_{55}$$Al$$_{10}$$Ni$$_{5}$$Cu$$_{30}$$ alloy films (50-100 $$mu$$m thickness) caused by radiation with 300-500 keV H, Ag, Cu and Au ions has been studied. The results of XRD indicated that a metastable primary phase was formed in the alloy by the heat treatment after ion irradiation, but no difference was observed just after the ion irradiation at room temperature. Furthermore, higher incident Au ion fluence effectively suppressed thermal precipitation of the Zr$$_{2}$$Ni type crystalline phase in the alloy. The deposited energy dependence of the precipitation behavior indicated an increase of the nucleation sites by the implanted metal atoms, simultaneously with a decrease of the growth rate by higher energy deposition density.

Oral presentation

Improvement of gasochromic properties in tungsten oxide by ion irradiation

Takano, Katsuyoshi; Inoue, Aichi; Yamamoto, Shunya; Yoshikawa, Masahito

no journal, , 

Tungsten oxide has been studied as a gasochromic material to apply to optical hydrogen gas sensors. The gasochromic coloration of tungsten oxide exposing hydrogen is related to a defect of oxygen atoms in the crystal of tungsten oxide. In this study, the gasochromic coloration of tungsten oxide films irradiated by helium ion beam at 350 keV was investigated, to create the defect by ion beam irradiation. Then the gasochromic coloration were measured an optical transmission. The coloration is enhanced with the increasing the amount of irradiation in 350 keV beam than un-irradiated samples. Therefore, the gasochromic coloration can be improved by ion beam irradiation.

Oral presentation

Characterization of silicon carbide coating synthesized from Si-based polymers

Sugimoto, Masaki; Takano, Katsuyoshi; Wach, R. A.; Yoshikawa, Masahito

no journal, , 

Silicon carbide (SiC) ceramic coating coating can be utilized for gas separation in process for hydrogen production. We developed the SiC coating by precursor polymer method. Spinning method was applied to coat the Al$$_2$$O$$_3$$ ceramic plates with preceramic polymers of polycarbosilane and polyvinylsilane and their blends. The coated plates were cured by electron beam (EB) to the total dose of 2 MGy. The polymer on the surface was crosslinked with oxygen present in the atmosphere during irradiation. Samples were pyrolized at 850 $$^{circ}$$C in argon atmosphere in order to convert into SiC ceramics. Examination by SEM was applied to elucidate the coated surface and the gas of hydrogen, and nitrogen permeation was measured. Rutherford backscattering spectroscopy (RBS) using 2.0 MeV He$$^+$$ ions was employed to determine the composition and the thickness of the films.

Oral presentation

Raman studies on damage of C$$_{60}$$ thin films by fast-ion bombardment

Narumi, Kazumasa; Sakai, Seiji; Naramoto, Hiroshi; Maeda, Yoshihito

no journal, , 

no abstracts in English

Oral presentation

Characterization of gasochromic tungsten oxide films by RBS

Yamamoto, Shunya; Takano, Katsuyoshi; Inoue, Aichi; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

TOF mass spectrometry of secondary ions from HOPG target bombarded by fast cluster ion beams

Shibata, Hiromi*; Tsuchida, Hidetsugu*; Ito, Akio*; Saito, Yuichi; Chiba, Atsuya; Narumi, Kazumasa; Arakawa, Kazuo

no journal, , 

no abstracts in English

11 (Records 1-11 displayed on this page)
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