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Journal Articles

Mictomagnetism and suppressed thermal conduction of the prototype high-entropy alloy CrMnFeCoNi

Yang, J.*; Ren, W.*; Zhao, X.*; Kikuchi, Tatsuya*; Miao, P.*; Nakajima, Kenji; Li, B.*; Zhang, Z.*

Journal of Materials Science and Technology, 99, p.55 - 60, 2022/02

High-entropy alloys are characteristic of extensive atomic occupational disorder on high-symmetric lattices, differing from traditional alloys. Here, we investigate magnetic and thermal transport properties of the prototype face-centered-cubic high-entropy alloy CrMnFeCoNi by combining physical properties measurements and neutron scattering. Direct-current (dc) and alternating-current (ac) magnetizations measurements indicate a mictomagnetic behavior with coexisting antiferromagnetic and ferromagnetic interactions in the entire temperature region and three anomalies are found at about 80, 50, and 20 K, which are related to the paramagnetic to antiferromagnetic transition, the antiferromagnetic to ferromagnetic transition, and the spin freezing, respectively. The electrical and thermal conductivities are significantly reduced compared to Ni and the temperature dependence of lattice thermal conductivity exhibits a glass-like plateau. Inelastic neutron scattering measurements suggest weak anharmonicity so that the thermal transport is expected to be dominated by the defect scattering.

Journal Articles

Direct ${it in-situ}$ temperature measurement for lamp-based heating device

Sumita, Takehiro; Sudo, Ayako; Takano, Masahide; Ikeda, Atsushi

Science and Technology of Advanced Materials; Methods (Internet), 2(1), p.50 - 54, 2022/02

Journal Articles

High reactivity of H$$_{2}$$O vapor on GaN surfaces

Sumiya, Masatomo*; Sumita, Masato*; Tsuda, Yasutaka; Sakamoto, Tetsuya; Sang, L.*; Harada, Yoshitomo*; Yoshigoe, Akitaka

Science and Technology of Advanced Materials, 23(1), p.189 - 198, 2022/00

GaN is an attracting material for power-electronic devices. Understanding the oxidation at GaN surface is important for improving metal-oxide-semiconductor (MOS) devices. In this study, the oxidation at GaN surfaces depending on the GaN crystal planes (+c, -c, and m-plane) was investigated by real time XPS and DFT-MD simulation. We found that H$$_{2}$$O vapor has the highest reactivity due to the spin interaction between H$$_{2}$$O and GaN surfaces. The bond length between the Ga and N on the -c GaN surface was increased by OH attacking the back side of three-fold Ga atom. The chemisorption on the m-plane was dominant. The intense reactions of oxidation and Al$$_{x}$$Ga$$_{1-x}$$N formation for p-GaN were observed at the interface of the Al$$_{2}$$O$$_{3}$$ layer deposited by ALD using H$$_{2}$$O vapor. This study suggests that an oxidant gas other than H$$_{2}$$O and O$$_{2}$$ should be used to avoid unintentional oxidation during Al$$_{x}$$Ga$$_{1-x}$$N atomi layer deposition.

Journal Articles

The Possible transition mechanism for the meta-stable phase in the 7xxx aluminium

Bendo, A.*; Matsuda, Kenji*; Nishimura, Katsuhiko*; Nunomura, Norio*; Tsuchiya, Taiki*; Lee, S.*; Marioara, C. D.*; Tsuru, Tomohito; Yamaguchi, Masatake; Shimizu, Kazuyuki*; et al.

Materials Science and Technology, 36(15), p.1621 - 1627, 2020/09

 Times Cited Count:1 Percentile:0(Materials Science, Multidisciplinary)

Metastable phases in aluminum alloys are the primary nano-scale precipitates which have the biggest contribution to the increase in the tangible mechanical properties. The continuous increase in hardness in the 7xxx aluminum alloys is associated with the phase transformation from clusters or GP-zones to the metastable $$eta'$$ phase. The transformation which is structural and compositional should occur following the path of the lowest activation energy. This work is an attempt to gain insight into how the structural transformation may occur based on the shortest route of diffusion for the eventual structure to result in that of $$eta'$$ phase. However, for the compositional transformation to occur, the proposed mechanism may not stand, since it is a prerequisite for the atoms to be at very precise positions in the aluminum lattice, at the very beginning of structural transformation, which may completely differ from that of the GP-zones atomic arrangements.

Journal Articles

Residual stresses in steel rod with collar formed by partial diameter-enlarging technique

Fukuda, Kojiro*; Tomota, Yo*; Harjo, S.; Gong, W.*; Woo, W.*; Seong, B. S.*; Kuwahara, Yoshitaka*; Ikuta, Fumiaki*

Materials Science and Technology, 33(2), p.172 - 180, 2017/01

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Investigation of microstructure in additive manufactured Inconel 625 by spatially resolved neutron transmission spectroscopy

Tremsin, A. S.*; Gao, Y.*; Dial, L. C.*; Grazzi, F.*; Shinohara, Takenao

Science and Technology of Advanced Materials, 17(1), p.324 - 336, 2016/07

 Times Cited Count:17 Percentile:61.27(Materials Science, Multidisciplinary)

Journal Articles

Studies of radiation effects on semiconductor devices at JAEA

Oshima, Takeshi

Proceedings of the 30th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.9 - 16, 2011/12

no abstracts in English

Journal Articles

Verification of soft-error rate estimation method in a logic LSI

Makino, Takahiro; Onoda, Shinobu; Hirao, Toshio; Oshima, Takeshi; Kobayashi, Daisuke*; Hirose, Kazuyuki*

Proceedings of the 28th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.35 - 40, 2009/12

We want to reveal the relation between SET-induced soft-error rates ($$SER_{SET}$$s) and SET pulse-width distribution to be able to reduce the $$SER_{SET}$$ with an SET filter like an RC filter or a temporal latch architecture. By considering the relation between $$SER_{SET}s$$ and SET pulse-width, we can determine the minimum time constant for the SET filter to reduce the $$SER_{SET}$$ effectively. A theoretical estimation has been proposed to obtain $$SER_{SET}s$$ in a logic LSI from SET pulse-widths measured in logic cells and the latch probability of SET pulses at flip-flops (FFs) used in logic LSIs. However, the estimation method has not been verified yet. In this paper, we verify the theoretical estimation method.

Journal Articles

Unrepairable DNA damage site composed of clustered lesions along ion particle tracks

Yokoya, Akinari; Shikazono, Naoya; Fujii, Kentaro; Ushigome, Takeshi*; Suzuki, Masao*; Urushibara, Ayumi; Watanabe, Ritsuko

Proceedings of the 27th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, 8 Pages, 2008/12

It has been indicated that ion particle irradiation to living cells causes a clustered DNA damage site, defined as two or more lesions formed within a few nano meters, in a cell nuclei. The clustered damage is less readily repaired by enzymatic repair system so that it induces biological effects, such as mutation induction. We have studied the mechanism of clustered damage induction by biochemical approaches using closed circular plasmid DNA as a model molecule to be irradiated with He ions from TIARA. We have used base excision repair proteins as enzymatic probes to quantify base lesions. We have also applied a novel method using DNA denaturation to visualize multiple single strand breaks which hardly be detected by conventional method. Our recent results will be reported in this seminar.

Journal Articles

Transient current and mapping using focused heavy-ion microbeams with several hundreds of MeV

Onoda, Shinobu; Hirao, Toshio; Oshima, Takeshi

Proceedings of the 27th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.43 - 46, 2008/12

no abstracts in English

Journal Articles

Radiation degradation modeling of triple-junction space solar cells

Sato, Shinichiro; Imaizumi, Mitsuru*; Oshima, Takeshi

Proceedings of the 27th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.37 - 42, 2008/12

Degradation modeling of triple junction (3J) solar cell due to proton and electron irradiation is performed with the use of a one dimensional optical device simulator. By fitting external quantum efficiencies of the 3J solar cells degraded by proton or electron irradiation, the short circuit current (Isc) and open circuit voltage (Voc) are simulated. These simulated values are in good accordance with the experimental data. In this modeling, carrier removal rate of base layer ($$R_C$$) and the damage coefficient of minority carrier diffusion length ($$K_L$$) in each sub cell are considered as radiation degradation parameters. NIEL (Non Ionizing Energy Loss) analysis for both radiation degradation parameters is discussed. The radiation degradation of a 3J solar cell can be predicted from correlativity between NIEL and radiation degradation parameters.

Journal Articles

Decrease in ion beam induced charge of 6H-SiC diodes

Onoda, Shinobu; Iwamoto, Naoya; Oshima, Takeshi; Hirao, Toshio; Kawano, Katsuyasu*

Proceedings of the 26th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.35 - 40, 2007/12

no abstracts in English

Journal Articles

Charge collection efficiency of 6H-SiC diodes damaged by electron irradiation

Iwamoto, Naoya; Oshima, Takeshi; Onoda, Shinobu; Hishiki, Shigeomi*; Murakami, Makoto; Nakano, Itsuo*; Kawano, Katsuyasu*

Proceedings of the 26th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.27 - 30, 2007/12

no abstracts in English

Journal Articles

Electrical characteristics of 6H-SiC MOSFETs after high dose irradiation

Oshima, Takeshi; Hishiki, Shigeomi*; Iwamoto, Naoya; Reshanov, S. A.*; Pensl, G.*; Kojima, Kazutoshi*; Kawano, Katsuyasu*

Proceedings of the 26th Symposium on Materials Science and Engineering, Research Center of Ion Beam Technology Hosei University, p.31 - 34, 2007/12

no abstracts in English

Journal Articles

Possible weak magnetism in MB$$_6$$ (M: Ca, Ba) probed by muon spin relaxation and muon level-crossing resonance

Kuroiwa, Sogo*; Takagiwa, Hiroyuki*; Yamazawa, Maki*; Akimitsu, Jun*; Koda, Akihiro*; Kadono, Ryosuke*; Oishi, Kazuki; Higemoto, Wataru; Watanabe, Isao*

Science and Technology of Advanced Materials, 7(1), p.12 - 16, 2006/01

 Times Cited Count:4 Percentile:19.96(Materials Science, Multidisciplinary)

The temperature dependence of muon spin relaxation rate exhibits a significant increase below $$sim$$130 K in CaB$$_6$$ and $$sim$$110 K in BaB$$_6$$, while no sigh of spontaneous muon precession signal under a zero field is observed. Moreover, the electric field gradient at the boron site measured by muon level-crossing resonance exhibits a step like change at $$sim$$110 K in CaB$$_6$$. These results suggest a change in electronic state and the associated emergence of weak random magnetism below 110-130 K in these alkaline earth hexaborides.

Journal Articles

Depth profile of oxide-trapped charges in 6H-SiC metal-oxide-semiconductor structures irradiated with gamma-rays

Yoshikawa, Masahito; *; Oshima, Takeshi; Ito, Hisayoshi; Nashiyama, Isamu; Okumura, Hajime*; Yoshida, Sadafumi*

14th Symp. on Materials Science and Engineering, Research Center of Ion Beam Technology, Hosei Univ., 0, p.159 - 165, 1996/00

no abstracts in English

Journal Articles

Hot-implantation of nitrogen and aluminumions into SiC semiconductor

Ito, Hisayoshi; Oshima, Takeshi; Aoki, Yasushi; Yoshikawa, Masahito; Nashiyama, Isamu; Okumura, Hajime*; Yoshida, Sadafumi*

14th Symp. on Materials Science and Engineering, Research Center of Ion Beam Technology, Hosei Univ., 0, p.147 - 150, 1995/00

no abstracts in English

Journal Articles

Characterization of defects in hot-implanted $$beta$$-SiC

Ito, Hisayoshi; Aoki, Yasushi; Yoshikawa, Masahito; Nashiyama, Isamu; Okumura, Hajime*; Yoshida, Sadafumi*

13th Symp. on Materials Science and Engineering, Research Center of Ion Beam Technology, Hosei Nniv., 0, p.75 - 80, 1994/12

no abstracts in English

Journal Articles

A Luminescence study of ion-irradiated aromatic polymers

Aoki, Yasushi; Namba, Hideki; Hosoi, Fumio; Nagai, Shiro

ACS Symposium Series, 579; Polymeric Materials for Microelectronic Applications,Science and Technology, 0, p.45 - 50, 1994/00

no abstracts in English

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