ナガノ タカトシ永野 隆敏講師Takatoshi NAGANO
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論文
- ロータス型多孔質熱電材料を用いた新しい熱電変換デバイスの可能性
池田輝之; 永野 隆敏; 篠嶋妥
機能材料 2019 年39 巻p. 52-59, 2019年07月10日, ［査読有り］ - 析出硬化系ステンレス鋼の冷間鍛造加工プロセスの開発
1)大貫 啓人; 和田 正勝; 五十嵐 雅高; 隠岐 裕康; 飛田 厚; 田代 優; 永野 隆敏; 岩瀬 謙二; 鈴木 徹也, 自動車技術会
自動車技術会論文集, 2019年01月26日, ［査読有り］ - 第一原理計算によるAl–Zn–Mg合金中の析出物水素偏析界面における強度評価
永野 隆敏; 川崎 優太; 篠嶋 妥; 伊藤 吾朗, Ab initio calculation of the tensile deformation of Al–Zn–Mg alloy models was performed to clarify the mechanism for hydrogen embrittlement in the Al–Zn–Mg alloy. The atomistic models of Al/MgZn2 boundaries containing a hydrogen atom, which the authors obtained previously, were used as the initial stable structures with hydrogen segregated at η1, η2, η4 interfaces (notation used by J. Gjønnes and Chr. J. Simensen). The models were strained uniaxially at a constant rate and their total energies after the structural relaxation were calculated by the ab initio method. It has been found that the hydrogen atom trapped near the Al matrix/MgZn2 precipitate interface deteriorates the strength of the Al–Zn–Mg alloys by weakening the bonding strength between Al and Mg–Zn. The authors have proposed that the interface strength can be estimated by the maximum of the derivative of the cohesive energy per unit area and have found that η4 shows the highest strength under tensile deformation. The proposed criteria can be applied to estimate the interface strength of various materials., 永野 隆敏, 川崎 優太, 篠嶋 妥, 伊藤 吾朗
軽金属 / 68 巻 (2018) 4 号, 2018年04月30日, ［査読有り］ - Screening of Undesirable Elements Raising the Electrical Resistivity in Very Narrow Cu Wires by Ab Initio Calculation
Takatoshi Nagano; Kunihiro Tamahashi; Takashi Inami; Yasushi Sasajima; Jin Onuki, We estimated segregation energy for compound impurities at the grain boundary in very narrow Cu wires using the ab initio calculation. From the calculation results, we clarified that the impurities such as FeO, Fe(ClO), TiO and Ti(ClO) have a strong segregation tendency at the Cu grain boundaries. The FE-TEM observation results of the Cu wires with Fe impurity atoms confirmed that the impurity atoms led to smaller grain sizes than the impurity-free case. The resistivity was measured as a function of the Cu wire width for various Fe impurity concentrations and the wire resistivity became higher with increased impurity concentration. (C) 2017 The Electrochemical Society. All rights reserved., ELECTROCHEMICAL SOC INC
JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 2017年, ［査読有り］ - 第一原理計算によるAl–Zn–Mg合金中の水素の存在位置の解析
永野 隆敏; 篠嶋 妥; 伊藤 吾朗,Ab initio calculation study on the site of hydrogen in Al–Zn–Mg alloys was performed to clarify the mechanism of hydrogen segregation, aiming to understand the mechanism for hydrogen embrittlement in Al–Zn–Mg alloys. In order to determine stable structures with hydrogen at grain boundaries as well as inside the grain, atomistic models of Al matrix, Al/Al and Al/MgZn2 boundaries containing a hydrogen atom were constructed, and their total energies as well as stable structures were calculated by the ab initio method. We defined and estimated the formation energy of hydrogen and compared the stability of segregated hydrogen in Al matrix, Al/Al and Al/MgZn2 boundaries. We found that hydrogen has a tendency to segregate in Al/MgZn2 boundaries, η1, η4, η2 (notation used by J. Gjønnes and Chr. J. Simensen) in this order. This is in accord with the thought that hydrogen is prone to be trapped on a semicoherent boundary, which was previously concluded from experimental results.
, 一般社団法人 軽金属学会
軽金属, 2016年08月30日, ［査読有り］ - Pinning Effect of Fe(ClO) and Ti(ClO) Compounds on Cu Grain Growth in Very Narrow Cu Wires
Takatoshi Nagano; Yasushi Sasajima; Nobuhiro Ishikawa; Kunihiro Tamahashi; Kishio Hidaka and Jin Onuki, We have clarified that the grain growth of Cu in very narrow Cu wires is reduced by the pinning effect of Fe(C10) and Ti(C10) compounds at a grain boundary based on results of a nano-order-analysis of aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) observations and an ab initio calculation. From the calculation, we estimated the segregation energy for the Fe(ClO) and Ti(ClO) compound impurities at the Cu grain boundary. Combining the ab initio calculation and measurement results, we proposed a pinning mechanism to suppress the grain boundary movement. (C) 2015 The Electrochemical Society. All rights reserved., ELECTROCHEMICAL SOC INC
ECS Electrochemistry Letters, 2015年, ［査読有り］ - Cs-Corrected STEM Observation and Atomic Modeling of Grain Boundary Impurities of Very Narrow Cu Interconnect
Takatoshi Nagano; Kunihiro Tamahashi; Yasushi Sasajima; Jin Onuki, Nano-order-analysis of grain boundary in very narrow Cu interconnect was performed for the first time using spherical aberration corrected Scanning Transmission Electron Microscope (Cs-corrected STEM). We focused our attention on both direct observation and ab initio calculation of impurities at the grain boundaries in Cu interconnect which depress the grain growth. STEM observation showed that Cl segregates at grain boundary, and that O exist in both grain boundary and interstitial. We estimated the segregation energy for the impurities at Cu grain boundary, and found that the result coincides with the observed tendency. (C) 2013 The Electrochemical Society. [DOI: 10.1149/2.001306eel] All rights reserved., ELECTROCHEMICAL SOC INC
ECS ELECTROCHEMISTRY LETTERS, 2013年 - Search for Barrier Materials for Cu Interconnects in Integrated Circuits
Yasushi Sasajima; Yuki Kimura; Tetsunori Tsumuraya; Takatoshi Nagano and Jin Onuki, We used the molecular dynamics simulation method to investigate the growth process of Cu polycrystalline films on three substrates Si, Ti and Ru during isothermal annealing. We focused on the influence of the adhesion strength and size mismatch between the substrate and Cu on crystallinity and orientational order of the films. Our simulation results clarified that Ru is an excellent material for the substrate/barrier metal to be used with Cu films. Based on the findings, we proposed a strategy to identify novel barrier materials to be used with Cu interconnect wires. One of the best candidate materials, IrMo, showed good epitaxy of Cu(111) in the ab initio calculation. (C) 2013 The Electrochemical Society. All rights reserved., ELECTROCHEMICAL SOC INC
ECS J. Solid State Sci. Tech., 2013年, ［査読有り］ - Effect of Point Defects on Lattice Constant in MgO Thin Film Deposited on Silicon (001) Substrate
S. Kaneko; T. Nagano; T. Ito; M. Yasui; T. Ozawa; M. Soga; Y. Motoizumi; H. Funakubo; M. Yoshimoto
European Physical Journal - Applied Physics, 2012年05月, ［査読有り］ - Substrate temperature dependence of electrical and structural properties of Ru films
Takatoshi Nagano; Kazuya Inokuchi; Kunihiro Tamahashi; Nobuhiro Ishikawa; Yasushi Sasajima; Jin Onuki, Microstructures and resistivities of sputtered Ru films were investigated as a function of substrate temperature to obtain a single-layered Ru barrier without a Ta/TaN under layer. High resistivity Ru films with a high density of crevices, which enhances Cu diffusion along the crevices, were formed by the conventional sputtering process, i.e., sputtering at room temperature and annealing at 400 degrees C-700 degrees C for 30 min in Ar + 3%H(2). But, crevice-free and smooth Ru films with low resistivity, the same as that for the bulk phase, were formed when substrate temperature add sputtering was raised to 700 degrees C. Ru films formed by this process had (002) preferred orientation and then Cu (111) was formed by plating. This result corresponded to the tendency predicted by ab initio calculations. (C) 2011 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2011年10月31日, ［査読有り］ - Ab-initio calculation of (101) and (100) surface forβ-FeSi2
谷本悟、永野隆敏, We study the atomic and electric structure on the (101) and (100) surface of β-FeSi2 by ab-initio calculation using the projector augmented wave method (PAW). The cohesive energy calculated with the slab model show that the structure Si layer biased in the surface is stable. The simulated STM images indicate that the charge in the neighborhood of Fermi level concentrated on Fe-Si bonding., ELSEVIER SCIENCE BV
Physics Procedia , Proceedings of APAC-SILICIDE 2010, 2011年02月, ［査読有り］ - Simulation of the growth of copper critical nucleus in dilute bcc Fe–Cu alloys
永野隆敏; 榎本正人, Fe-Cu合金のCu析出において、Cahn-Hilliardの非古典論を適用し、母相濃度と歪エネルギーの影響による析出核の濃度プロファイル、また、非線形拡散方程式を解くことで核成長における時間変化を計算した。
Scripta Materialia, 2006年04月, ［査読有り］ - Calculation of the interfacial energies between alpha and gamma iron and equilibrium particle shape
Masato Enomoto, The interfacial energies between alpha and gamma iron were calculated for Kurdjumov-Sachs (K-S), Nishiyama-Wassermann (N-W), and one orientation relationship (OR), which may represent irrational OR, with varying interface orientation. The relaxation of atomic Structure in the vicinity of the interface was performed by the Monte Carlo method using an embedded atom method (EAM) potential. Whereas the polar plot of calculated interfacial energies exhibited small and large Cusps for the K-S and N-W ORs, an almost equiaxed energy surface with shallow cusps was obtained for the irrational ORs. The equilibrium shape of an alpha particle, N-W oriented with the gamma matrix, was a thick rectangular plate with broad facets containing monatomic ledges. In contrast, the equilibrium shape of alpha particle, K-S oriented with the gamma matrix, was elongated nearly in the closed-packed directions with {112}(gamma) type and another broad facet that achieves relatively good thatching. The volume of these shapes in the Wulff space tends to be smaller for K-S than that of the N-W OR. The equilibrium shape of the grain boundary alpha particle at the gamma grain boundary was calculated under the assumption that the alpha particle has K-S OR with one of the two gamma grains using the modified Wulff construction proposed earlier. The variation of the shape of the alpha particle with gamma grain boundaries at an early stage of precipitation may primarily be ascribed to the change in the variant of the smallest nucleation activation energy and less prominently to the change in the gamma grain boundary energy., MINERALS METALS MATERIALS SOC
METALLURGICAL AND MATERIALS TRANSITIONS A, 2006年03月 - Simulation of the growth of Cu critical nucleus calculated incorporating strain energy in Fe-Cu alloys
永野隆敏,榎本正人
The Materials Research Society of Japan, 2005年09月, ［査読有り］ - Calculation of Interfacial Energy Between α and γ Iron Near a Rational Orientation Relationship
Masato Enomoto; Takatoshi Nagano; J.B. Yang, フェライト(α)/オーステナイト(γ)界面は鉄鋼の変態や組織形成に重要な役割を果たす。これまで、K-SやN-Wなどを有するα/γ界面について晶癖面など特定の面については界面エネルギーが検討されてきたが、界面エネルギーの最安定方位は少しずれている事についてO-lattice法と比較しながら検討した。, MINERALS, METALS & MATERIALS SOC
Proc.Int.Conf on Solid-Solid Phase Transformations in Inorganic Materials, TMS, 2005年03月, ［査読有り］ - Calculation of the Equilibrium Shape of TiN Particles in Iron
M Enomoto; ZG Yang; T Nagano, IRON STEEL INST JAPAN KEIDANREN KAIKAN
The IRON AND STEEL INSTITUTE OF JAPAN, 2004年 - Optimized structures of Si28 and Ba@Si28 clusters: Ab initio study
Kazuo Tsumuraya; Takatoshi Nagano; Haruki Eguchi; H.Takenaka, シリコンクラスレートは、Baなどの原子を内包させたときに生成されやすいことが報告されている。Ba原子位置のひとつであるSi28クラスタ－における構造安定性をBa原子の有無によって調べた。
International Journal of Quantum Chemistry, 2002年11月 - Exohedral Bonding Nature of Si Atom on the Ba@Si28 Cluster; Ab Initio Study
Kazuo Tsumuraya; Takatoshi Nagano; Haruki Eguchi; H.Takenaka, First-principle electronic structure is studied for the Si-28 and Ba @ Si-28 clusters. which are components of the clusters in silicon clathrate II. We obtain the geometrically optimized relaxed cage structures of the clusters and the exohedral binding nature of single Si atom on the Ba @ Si-28 clusters. The hollow Si-28 cluster relaxes into the Si-24 like cluster in the clathrate I having four exohedral Si atoms outside the hexagon in the Si-24 cluster. The hexagons on the Ba @ Si-28 cluster are deformed into a chair type with relaxation. The exohedral Si atom is the most stable at the edge center near the top that meets three pentagons, We have found for the first time that the exohedral Si atom forms the three-center covalent bond between the two caged Si atoms., JAPAN INST METALS
Materials Transactions, 2002年04月 - Electronic structure, bonding nature, and charge transfer in Ba@Si20 and Si20 clusters:An ab-initio study
Takatoshi Nagano; Kazuo Tsumuraya; Haruki Eguchi; D.J.Singh, First-principles electronic structure calculations are carried out for the Si20 and endohedral Ba@Si20 clusters, which appear in the silicon clathrate I and II. We analyze electronic structures, binding energies, charge transfers, and exohedral binding energies of single Si atoms on the Ba@Si20 clusters. We compare the electronic structures of the Ba@Si20 cluster with that of the corresponding hollow Si20 cluster. We find that, unlike the hollow ISi20 cluster which undergoes a structural change, the endohedral Ba atom in the Ba@Si20 cluster stabilizes the cage structure with Ci symmetry slightly distorted from Isymmetry. The computed geometrical charge transfer is 2.006e and the physical one is 0.063e for the endohedral Ba atom. The eigenstates of both the clusters can be understood on the basis of a simple model previously used to explain the spherical carbon fullerenes. The charge distribution, corresponded to the highest valence electron state, relates to the sp3 bonding nature of the cage Si atoms of the Ba@Si20 cluster. The top positions of the cage Si atoms on this cluster is the most unstable among the positions investigated despite the sp3 bonding of the cage atoms
the position on the center of edge is the most stable for the exohedral Si atom
the hollow site at the center of the pentagonal ring is the second. The two exohedral positions, top and 6c sites, around the Ba@Si20 cluster in the clathrate I are the most unstable among the positions. We discuss the mechanism of the growth of the clathrates I.
Physical Review B, 2001年10月 - Electronic structure, bonding nature, and charge transfer in Ba@Si-20 and Si-20 clusters: An ab initio study
T Nagano; K Tsumuraya; H Eguchi; DJ Singh, First-principles electronic structure calculations are carried out for the Si-20 and endohedral Ba@Si-20 clusters, which appear in the silicon clathrate I and II. We analyze electronic structures, binding energies, charge transfers, and exohedral binding energies of single Si atoms on the Ba@Si-20 clusters, We compare the electronic structures of the Ba@Si-20 cluster with that of the corresponding hollow Si-20 cluster. We find that, unlike the hollow I-h Si-20 cluster which undergoes a structural change, the endohedral Ba atom in the Ba@Si-20 cluster stabilizes the cage structure with C-i symmetry slightly distorted from I-h symmetry. The computed geometrical charge transfer is 2.006e and the physical one is 0.063e for the endohedral Ba atom. The eigenstates of both the clusters can be understood on the basis of a simple model previously used to explain the spherical carbon fullerenes. The charge distribution, corresponded to the highest valence electron state, relates to the sp(3) bonding nature of the cage Si atoms of the Ba@Si-20 cluster. The top positions of the cage Si atoms on this cluster is the most unstable among the positions investigated despite the sp(3) bonding of the cage atoms; the position on the center of edge is the most stable for the exohedral Si atom; the hollow site at the center of the pentagonal ring is the second. The two exohedral positions, top and 6c sites, around the Ba@Si-20 cluster in the clathrate I are the most unstable among the positions. We discuss the mechanism of the growth of the clathrates I., AMER PHYSICAL SOC
PHYSICAL REVIEW B, 2001年10月 - Ab-initio Prediction of Site Preferences Barium Atoms in a Silicon 46 Clathrate
Takatoshi Nagano; Kazuo Tsumuraya; Haruki Eguchi, Siクラスレートは、熱伝素子や超伝導素子として期待されている物質である。その構造のひとつであるSiクラスレート46におけるBa原子内包位置をPm3n-2aサイトであることを明らかにした。, PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE
Progress of Theoretical Physics Supplement ICCP5 (The 5th International Conference on omputational Physics), 2000年, ［査読有り］ - Formation Energies of Ba Atom in Sin (n=20,24,28) Clusters: Ab-initio Study
Takatoshi Nagano; Kazuo Tsumuraya; Haruki Eguchi, Siクラスレート内に面を共有して存在するクラスタ―Sin (n=20,24,28)にBa原子を内接させ、電子状態を解析し、その安定性の比較を行った。(基礎となる初期Si構造データ作成以外すべて), PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE
Progress of Theoretical Physics Supplement,ICCP5 (The 5th International Conference on Computational Physics), 2000年, ［査読有り］ - Ab-initio Calculation of Electronic Structure of Carbon Nitride : in Search of Super Hard Materials
Haruki Eguchi; Kszuo Tsumuraya; Takatoshi Nagano; S.Kihara, ダイヤモンドに代わる硬質材料として、炭素と窒素からなる物質を評価し、硬質材料としての可能性があることを示した`.
Society for the Advancement of Materal and Process Engineering, 1999年10月, ［査読有り］ - Bonding Nature of Si7 Bicapped Pentagon Cluster : Ab-initio Study
Haruki Eguchi; Kazuo Tsumuraya; Takatoshi Nagano; Shigemitsu Kihara, Si7原子からなるクラスターの電子状態を解析した。結合状態を正しく評価するには電子密度だけでなく、そのラプラシアンを評価することの必要性を明らかにした。
Materials Transactions.JIM,vol.40,No.11,pp.119801204, 1990年10月, ［査読有り］
講演・口頭発表等
- 転造加工高強度ボルトねじ谷部における組織変化と局所軟化部の観察
茨城大学大学院 理工学研究科 佐藤 優(修士 2 年),北村 裕介(修士 1 年),宍戸 亮一,佐藤 広幸,永野 隆敏
日本鉄鋼協会 第185回講演大会, 2023年03月09日, 日本鉄鋼協会
20230308, 20230310 - 水中Mgの反応によるアレルゲン金属イオン除去と第一原理計算を用いたその選定
○川村航希(茨城大学大学院)、永野隆敏(茨城大学大学院理工学研究科)
日本繊維機械学会,繊維学会 北陸支部 研究発表会, 2022年12月05日, 日本繊維機械学会 - 粒子法シミュレーションによる熱流体透過型多孔質熱電材料の熱伝達係数評価
茨城大工(学生)○佐々木 誠; 茨城大工(院生)Shiva Kumar Singh; 茨城大工永野 隆敏; 茨城大工池田 輝之; (株)ロータスサーマルソリューション井手 拓哉; (株)ロータスサーマルソリューション; (公財)若狭湾エネルギー研究センター中嶋 英雄
第15回日本熱電学会学術講演会, 2019年09月14日, 日本熱電学会 - 第一原理計算によるAl-Zn-Mg合金中の水素の存在位置の解析
川崎優太
軽金属学会 講演大会 第131回秋期大会, 2016年11月06日, 軽金属学会、茨城大学工学部（共催） - 材料開発における界面や表面を扱ったナノレベルシミュレーションとその有用性について
軽量化技術研究室・2011年度前期研究発表会, 2011年08月17日 - 第一原理計算によるβ-FeSi2(101)表面構造解析
永野隆敏
第１３回シリサイド系半導体研究会, 2009年04月03日, 末益崇, ［招待有り］
共同研究・競争的資金等の研究課題
産業財産権
