2024/10/28 更新

写真a

クタナ アレクサンダー
KUTANA Alexander
KUTANA Alexander
所属
未来社会創造機構 マテリアルイノベーション研究所 マテリアルDX研究部門 特任准教授
職名
特任准教授

学位 2

  1. B.S. ( 1996年6月 ) 

  2. Ph.D. ( 2003年8月 ) 

 

論文 65

  1. Topochemical Fluoride Exchange Reaction with Anionic Electrons toward Fluoride-Ion Conduction in Layered Ba<sub>2-<i>x</i></sub>A<sub><i>x</i></sub>NF<sub>1-<i>x</i> </sub> (A = Na, K)

    Pattanathummasid, C; Yasufuku, N; Asahi, R; Kutana, A; Hagihara, M; Mori, K; Takami, T

    CHEMISTRY OF MATERIALS   36 巻 ( 11 ) 頁: 5671 - 5677   2024年5月

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    出版者・発行元:Chemistry of Materials  

    Monovalent potassium substitution at the divalent barium sites of Ba2NF, a Ba2N electride analogue, led to fluoride-ion conduction in the two-dimensional (2D) interlayer space. Potassium substitution made the system chemically unstable for x ≥ 0.25 in Ba2-xKxNF1-x, and the nominal fluorine stoichiometry was not attained as the composition approached this region. Fluoride ions, fluoride vacancies, and interstitial anionic electrons (IAEs) coexisted in the 2D interlayer space of Ba1.8K0.2NF0.7·0.1e- because the missing charge of the absent fluoride ions was compensated for by IAEs. First-principles calculations demonstrated that the coexistence of these three species hindered smooth fluoride-ion diffusion on account of the IAEs acting as a scattering barrier. Chemical fluorination to replace these residual IAEs with fluoride ions via an exchange reaction led to the coexistence of only fluoride ions and their vacancies, resulting in fluoride-ion conduction. The obtained results demonstrate the first emergence of fluoride-ion conduction in an electride analogue, which is expected to motivate further exploration of this new family of fluoride-ion conductors. Our skeleton-retained anion exchange approach suggests that such 2D electrides may represent a fresh chemical space for realizing monovalent anionic conduction.

    DOI: 10.1021/acs.chemmater.4c00716

    Web of Science

    Scopus

  2. Limits of Hydrogen-Boosted Superconductivity in Borophene

    Li, XF; Kutana, A; Penev, ES; Yakobson, BI

    JOURNAL OF PHYSICAL CHEMISTRY C   128 巻 ( 1 ) 頁: 483 - 488   2023年12月

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    出版者・発行元:Journal of Physical Chemistry C  

    Two-dimensional (2D) boron, borophene, unlike the majority of other 2D materials, features a metallic ground state and is expected to show phonon-mediated superconductivity with a modest critical temperature, Tc. The recent prediction of enhanced Tc through hydrogenation in several 2D materials and the experimentally feasible hydrogenation of borophene naturally provoke the question of whether hydrogen can boost the Tc of borophene. Here, we employ first-principles calculations to examine the electronic structure, phonon dispersion, and electron-phonon coupling of borophene for varying H coverage. While the Tc’s for the selected most stable hydrogenated borophene (“borophane”) polymorphs are found to be not higher but lower than that of the parent borophene, our results suggest that the intrinsic superconductivity of borophene appears robust again modest “disorder” due to hydrogenation.

    DOI: 10.1021/acs.jpcc.3c06375

    Web of Science

    Scopus

  3. Machine learning and atomistic origin of high dielectric permittivity in oxides

    Shimano, Y; Kutana, A; Asahi, R

    SCIENTIFIC REPORTS   13 巻 ( 1 ) 頁: 22236   2023年12月

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    記述言語:英語   出版者・発行元:Scientific Reports  

    Discovering new stable materials with large dielectric permittivity is important for future energy storage and electronics applications. Theoretical and computational approaches help design new materials by elucidating microscopic mechanisms and establishing structure–property relations. Ab initio methods can be used to reliably predict the dielectric response, but for fast materials screening, machine learning (ML) approaches, which can directly infer properties from the structural information, are needed. Here, random forest and graph convolutional neural network models are trained and tested to predict the dielectric constant from the structural information. We create a database of the dielectric properties of oxides and design, train, and test the two ML models. Both approaches show similar performance and can successfully predict response based on the structure. The analysis of the feature importance allows identification of local geometric features leading to the high dielectric permittivity of the crystal. Dimensionality reduction and clustering further confirms the relevance of descriptors and compositional features for obtaining high dielectric permittivity.

    DOI: 10.1038/s41598-023-49603-2

    Web of Science

    Scopus

    PubMed

  4. Processing dynamics of carbon nanotube-epoxy nanocomposites during 3D printing

    Khater, AZ; Saadi, MASR; Bhattacharyya, S; Kutana, A; Tripathi, M; Kamble, M; Song, SW; Lou, MH; Barnes, M; Meyer, MD; Harikrishnan, VVJ; Dalton, AB; Koratkar, N; Tiwary, CS; Boul, PJ; Yakobson, B; Zhu, HY; Ajayan, PM; Rahman, MM

    CELL REPORTS PHYSICAL SCIENCE   4 巻 ( 10 )   2023年10月

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    出版者・発行元:Cell Reports Physical Science  

    Carbon nanotube (CNT)-reinforced polymer nanocomposites are promising candidates for a myriad of applications. Ad hoc CNT-polymer nanocomposite fabrication techniques inherently pose roadblocks to optimized processing, resulting in microstructural defects, i.e., void formation, poor interfacial adhesion, wettability, and agglomeration of CNTs inside the polymer matrix. Here, we show that a 3D printing technique offers improved processing of CNT-polymer nanocomposites. During printing, the shear-induced flow of an engineered nanocomposite ink through the micronozzle is beneficial, as it reduces the number of voids within the epoxy matrix, improves CNT dispersion and adhesion with epoxy, and partially aligns the CNTs. Such microstructural changes result in enhanced mechanical and thermal properties of the nanocomposites compared to their mold-cast counterparts. This work demonstrates the advantages of 3D printing in achieving improved processing dynamics for the fabrication of CNT-polymer nanocomposites with better structural and functional properties.

    DOI: 10.1016/j.xcrp.2023.101617

    Web of Science

    Scopus

  5. Challenges for fluoride superionic conductors: fundamentals, design, and applications

    Takami, T; Pattanathummasid, C; Kutana, A; Asahi, R

    JOURNAL OF PHYSICS-CONDENSED MATTER   35 巻 ( 29 )   2023年7月

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    記述言語:英語   出版者・発行元:Journal of Physics Condensed Matter  

    Electronics, which harnesses the properties of electrons, has made remarkable progress since its inception and is a cornerstone of modern society. Ionics, which exploits the properties of ions, has also had a profound impact, as demonstrated by the award of the Nobel Prize in Chemistry in 2019 for achievements related to lithium-ion batteries (LIBs). Ionic conduction in solids is the flow of carrier ions through a solid owing to an electrical or chemical bias. Some ionic materials have been studied intensively because their ionic conductivities are higher than those of liquids, even though they are solids. Among various conductive species, fluoride ions are the most promising charge carriers for fluoride-ion batteries (FIBs) as post LIBs. Increasing fluoride-ion conductivity toward the superionic conductive region at room temperature would be a breakthrough for the room-temperature operation of all-solid-state FIBs. This review focuses on fluoride-ion conductors, from the general concept of ions to the characteristics of fluoride ions. Fluoride-ion conductors are classified according to material type and form, and our current understanding, identification of problems, and future directions are discussed from experimental and theoretical physics perspectives.

    DOI: 10.1088/1361-648X/accb32

    Web of Science

    Scopus

    PubMed

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