研究者詳細 - 長田　実

論文 - 長田　実

分割表示 235 件中 21 - 40 件目／全件表示 >>

佐波正浩, 中村俊博, 森河務, 井上学, 内田衛, 藤波知之, 秦朋美, 相木文男, 森田顕, 小田幸典, 松原浩, 田代雄彦, 姜俊行, 宮田麻衣, 竹林浩史, 野村広正, 平藤哲司, 津田哲哉, 安田幸司, 幸塚広光, 長田実, 土屋哲男, 笹野順司, 伊﨑昌伸, 滝川浩史, 小島啓安, 西川博昭, 川名淳雄, 坂本幸弘, 竹内貞雄, 斎藤秀俊, 矢嶋龍彦, 鈴木雅人, 菊地竜也, 近藤敏彰, 岩崎光伸, 阿相英孝, 土谷博昭, 幅崎浩樹, 松本歩, 八重真治, 小崎匠, 木口忠広, 印部俊雄, 遠藤幸典, 太田伶美, 奴間伸茂, 鷹野一朗, 新納弘之, 星野薫, 渡邊陽一, 三阪佳孝, 松本克才, 関根誠, 谷泰弘, 清水健一, 松島永佳, 高橋和裕, 林広司, 星芳直, 小岩仁子, 長瀧敬行, 日野実

表面技術 71 巻 ( 2 ) 頁： 96 - 182 2020年2月

2次元ナノシートの形態制御と機能材料への応用

長田実

セラミックス 55 巻頁： 390 - 394 2020年

Unraveling the structural features of Dion-Jacobson-type layered perovskite-related material HCa2Nb3O10·1.5H2O Open Access

Zhang, ZH; Kano, J; Morita, S; Shimokawa, H; Osada, M

DALTON TRANSACTIONS 55 巻 ( 27 ) 頁： 10196 - 10202 2026年7月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Dalton Transactions

Hydrated layered oxides are widely encountered, yet the presence of disordered interlayer water often complicates crystal structure determination from laboratory X-ray diffraction. Here, we report the crystal structure of the Dion–Jacobson-type layered perovskite-related material HCa<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf>·1.5H<inf>2</inf>O, solved from synchrotron X-ray diffraction data by combining direct methods in reciprocal space, Le Bail whole-pattern fitting, and Rietveld refinement. The hydrate crystallizes in a tetragonal structure with space group P4<inf>2</inf>2<inf>1</inf>2 (a = 7.7070(5) Å, c = 32.4870(3) Å). Incorporation of partially occupied interlayer water-oxygen sites on the (110) plane at z = 0 and 1/2 successfully reproduces the low-angle 00l reflections while preserving the Ca<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> framework. The resulting crystallographic model explicitly resolves the arrangement of interlayer water molecules and provides a robust structural foundation for band-structure calculations as well as for the rational design of hydration-controlled intercalation, exfoliation, and composite materials based on layered perovskite-related materials.

DOI： 10.1039/d5dt03086b

2D dielectrics and ferroelectrics: emerging materials, physics and design principles 招待有り査読有り Open Access

Minoru Osada

Applied Physics Express 19 巻頁： 070101-1 - 070101-16 2026年7月

Breathable, water-repellent γ-MnOOH nest production by vapor-assisted conversion 査読有り Open Access

Takahiro Kozawa, Kayo Fukuyama, Minoru Osada, Hiroya Abe

Materials Advances 7 巻 ( 12 ) 頁： 6091 - 6100 2026年6月

Vacuum-level-referenced band tuning induced by ion exchange and exfoliation in layered perovskite KCa2Nb3O10 査読有り国際共著

Zhang, ZH; Oshime, N; Hamasaki, Y; Osada, M; Morita, S; Takaguchi, Y; Yamagami, M; Okubo, T; Horigane, K; Ikeda, N; Fujii, T; Gemeiner, P; Janolin, PE; Hirose, S; Kano, J

JOURNAL OF APPLIED PHYSICS 139 巻 ( 23 ) 2026年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Applied Physics

Ion exchange and exfoliation are widely used chemical processes for layered perovskites; however, their impact on vacuum-level-referenced electronic band alignment remains unclear. In this study, we investigate the crystal and electronic band structures of the Dion–Jacobson-type layered perovskite KCa<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf>, its protonated form HCa<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf>, and exfoliated Ca<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> nanosheets. Synchrotron x-ray powder diffraction reveals that KCa<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> crystallizes in the monoclinic space group P2<inf>1</inf>/m, whereas HCa<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> adopts a tetragonal structure with space group P4<inf>2</inf>2<inf>1</inf>2, indicating enhanced structural symmetry upon protonation. Energy diagrams referenced to the vacuum level are experimentally determined for all three compounds, enabling direct comparison of valence-band positions and in-gap states induced by ion exchange and exfoliation. In HCa<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf>, a hydrogen-bonded network is found to play a key role in controlling the formation and energy level of in-gap states. These results demonstrate that chemical processing provides an effective route for vacuum-level-referenced band tuning in layered perovskites, offering a practical guideline for band engineering in photocatalytic and related functional oxide materials.

DOI： 10.1063/5.0321518

Web of Science

Scopus

Tailored Synthesis of Doped Non-Layered Oxide Nanosheets Using Designed Solid-State Surfactants 査読有り Open Access

Ito, K; Yamamoto, E; Hayashi, K; Kurimoto, D; Kobayashi, M; Osada, M

ADVANCED SCIENCE 頁： e75720 2026年5月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Advanced Science

Precise compositional control of 2D nanosheets is critical for advancing the rational design of 2D functional materials. Solid-state surfactant templating has recently emerged as a powerful strategy for synthesizing non-layered 2D oxide nanosheets; however, its broader applicability has been constrained by the lack of rational design principles for multicomponent precursors. Here, we establish a general framework for precursor surfactant design that enables programmable compositional control in non-layered 2D oxide nanosheets. Using cerium oxide doped with a range of rare-earth elements (La, Pr, Sm, Gd, Yb, Y, and Sc) as a model system, we show that precursor crystal compositions are determined not only by nominal stoichiometry but also by selective incorporation governed by ionic radii. In contrast, the resulting nanosheet compositions deviate systematically due to differences in dopant reactivity during condensation, which correlates with the hydrolysis tendency of the metal cations. By rationally balancing these competing incorporation and reaction effects, nanosheets with targeted compositions are achieved. This work elevates solid-state surfactant templating from an empirical method to a designable synthetic platform, offering broadly applicable principles for the synthesis of compositionally programmed 2D oxide nanosheets.

DOI： 10.1002/advs.75720

その他リンク： https://advanced.onlinelibrary.wiley.com/doi/full-xml/10.1002/advs.75720

Tailored Synthesis and Band-Structure Modulation in Nitrogen-Doped Perovskite Oxide Nanosheets Open Access

Kobayashi, M; Oyabu, I; Sugimoto, H; Yamamoto, E; Osada, M

INORGANIC CHEMISTRY 65 巻 ( 19 ) 頁： 10803 - 10811 2026年5月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Inorganic Chemistry

Two-dimensional (2D) inorganic materials provide a powerful platform for electronic-structure engineering through precise control of the composition and crystal structure. While cation substitution has been widely exploited in oxide nanosheets, anion engineering remains far less developed, particularly in molecularly thin oxynitride systems with controlled nitrogen doping. Here, we report a generalizable route to nitrogen-doped perovskite oxide nanosheets that overcomes long-standing challenges associated with nitridation and structural instability. Using Dion–Jacobson (DJ)-type perovskite oxynitrides, RbSr<inf>2</inf>(Nb<inf>1–x</inf>Ta<inf>x</inf>)<inf>3</inf>O<inf>10–y</inf>N<inf>y</inf>, as a model platform, we demonstrate that the combination of cation substitution and nitrogen doping enables systematic modulation of both composition and electronic band structure in 2D perovskites. DJ-type perovskite oxynitrides with substantial nitrogen incorporation can be obtained via an unexpected transformation from pseudo–Ruddlesden–Popper-type phases, induced by alkali metal salt-assisted nitridation followed by simple aqueous treatment, without altering the anion composition. These oxynitrides are subsequently exfoliated into single-layer nanosheets that preserve the perovskite framework and the designed cation stoichiometry. Direct determination of both valence and conduction band edges by combined ultraviolet and inverse photoelectron spectroscopy reveals composition-dependent, nonmonotonic band alignment behavior that cannot be resolved by indirect optical or electrochemical approaches. This work establishes an integrated materials and characterization framework for the rational electronic-structure design in 2D oxynitride nanosheets.

DOI： 10.1021/acs.inorgchem.6c01293

Tailored Nitrogen Doping of Titania Nanosheets Revealed by a Combined Photoelectron Spectroscopy 査読有り Open Access

M. Kobayashi, N. Hagishima, E. Yamamoto, M. Osada

Adv. Mater. Interfaces 12 巻頁： e00570H 2025年11月

Highly efficient synthesis of small-diameter single-walled carbon nanowires through transformation of polyyne molecules into long linear carbon chains inside single-walled carbon nanotubes 査読有り

Maruyama, T; Sunako, H; Zhao, C; Saida, T; Haruyama, Y; Morita, S; Osada, M; Zhao, XL

CHEMICAL PHYSICS LETTERS 877 巻 2025年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemical Physics Letters

Single-walled carbon nanowires (SWCNWs)—long linear carbon chains (LLCCs) or carbynes confined inside single-walled carbon nanotubes (SWCNTs)—are synthesized by inserting polyynes (C<inf>2n</inf>H<inf>2</inf>) as a carbon source into SWCNTs, followed by annealing under high vacuum. By optimizing the polyyne solution concentration, high-yield SWCNWs (diameters <0.8 nm) were efficiently prepared. The I<inf>L</inf>/I<inf>G</inf> ratio in Raman spectrum reached 3.6, and it was much higher than the reported values for such small-diameter SWCNWs. Thus, high-density LLCCs were encapsulated inside small-diameter SWCNTs. I<inf>L</inf>/I<inf>G</inf> was markedly enhanced under the resonance condition of the host SWCNTs, where the energy was effectively transferred from the host SWCNTs to LLCCs.

DOI： 10.1016/j.cplett.2025.142308

Web of Science

Scopus

溶かさない界面活性剤で作る新しい二次元材料招待有り

山本瑛祐, 長田実

J. Jpn., Soc. Colour Mater. 98 巻 ( 9 ) 頁： 242 - 248 2025年9月

Tunable plasticity and multilevel photo-memory enabled by type-II heterojunctions in 2D nanosheet-based organic optical synapses 査読有り国際共著国際誌

Li, LF; Huang, QM; Osada, M; Zhao, JC; Li, Y

JOURNAL OF PHYSICS D-APPLIED PHYSICS 58 巻 ( 35 ) 2025年9月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D Applied Physics

The rapid development of the Internet of Things is driving advances in neuromorphic photonic computing systems that leverage light for highly efficient and parallel information processing. Note that to achieve neuromorphic computing with artificial optical synapses, tunable synaptic plasticity and photo-memory functions enabled by direct optical modulation are essential. In this study, we design an organic optical synaptic device with a two-dimensional (2D) metal oxide nanosheet as the charge storage layer, demonstrating bimodal synaptic plasticity and multilevel photo-memory. The precise layer-by-layer liquid deposition technology enables direct integration of 2D Cs<inf>2.7</inf>W<inf>11</inf>O<inf>35</inf>1.3− nanosheet films with controllable thickness into the device for charge storage. Through interfacial band engineering, a type-II heterojunction is established between the organic semiconductor channel and the inorganic nanosheet, enabling gate-voltage-free photogenerated charge transfer and storage. Under optical modulation, the device exhibits tunable synaptic behaviors ranging from short- to long-term plasticity and a multilevel photo-memory capability with a retention time of 103 s. Then, we confirm the potential of the synaptic device for highly efficient neuromorphic computing, demonstrating a recognition capability with a high accuracy of 97.8%. Therefore, our device sheds new light on the development of optical computing systems.

DOI： 10.1088/1361-6463/adfbfa

Web of Science

Scopus

Covalent Functionalization of MXenes with Porphyrin for Visible-Light Activation in Energy Conversion Nanodevices 査読有り国際共著国際誌

Li, H; Canton-Vitoria, R; Urano, Y; Nayak, SK; Yamamoto, E; Kobayashi, M; Kitaura, R; Osada, M

SMALL 21 巻 ( 38 ) 頁： e03895 2025年9月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Small

MXenes such as Ti<inf>3</inf>C<inf>2</inf> and Ti<inf>3</inf>CN are 2D materials characterized by the presence of a T<inf>x</inf> phase that passivates the reactive titanium surface. Modifying their chemical composition to anchor target molecules is of great interest for addressing key challenges, such as enhancing the conversion of visible light into electricity. In this study, a covalent functionalization strategy is developed to modify the T<inf>x</inf> phase of Ti<inf>3</inf>C<inf>2</inf> or Ti<inf>3</inf>CN with alkyl amines, followed by coupling with Zn-porphyrin. This process activates the optical properties of MXenes without causing any damage. X-ray photoelectron spectroscopy and infrared spectroscopy are pivotal in confirming the covalent functionalization, while thermogravimetric analysis, transmission electron microscopy, and additional techniques provided further insights into structural and chemical features. Spectroelectrochemical investigations reveal carrier injection into MXenes under light illumination, potentially enhancing conductivity. Photodetectors fabricated from these films demonstrate responsivities of 1.4–15.0 A W−1 and external quantum efficiencies ranging from 1300 to 2830% in the visible range, making them comparable to well-established hybrid 2D nanomaterials like MoS<inf>2</inf> and WS<inf>2</inf>.

DOI： 10.1002/smll.202503895

Web of Science

Scopus

PubMed

Beyond Fertilizers: NH4ZnPO4 for the Reversible Chemical Storage of Ammonia 査読有り国際誌

Kozawa, T; Hashiba, T; Fukuyama, K; Abe, H; Morita, S; Osada, M; Naito, M

ADVANCED MATERIALS INTERFACES 12 巻 ( 8 ) 2025年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Advanced Materials Interfaces

Enhancing NH<inf>3</inf> as a carbon-free energy carrier of H<inf>2</inf> and next-generation fuel is a promising approach for a sustainable society. Chemically storing NH<inf>3</inf> molecules in crystal structures offers better selectivity and reusability than storage in traditional porous materials based on physicochemical adsorption; however, designing materials that can be reversibly stored in structural gaps is still a significant challenge. Herein, the use of NH<inf>4</inf>ZnPO<inf>4</inf>, which is previously used as a fertilizer, is proposed as an NH<inf>3</inf> uptake material through a chemical storage mechanism. The NH<inf>4</inf>ZnPO<inf>4</inf> particles synthesized by a wet mechanochemical method with monoclinic and hexagonal crystal structures can incorporate NH<inf>3</inf> molecules and directly transform them into NH<inf>4</inf>Zn(NH<inf>3</inf>)PO<inf>4</inf> without producing byproducts. The chemical storage mechanism depends on the particle morphology; therefore, the uptake amount per surface area surpasses that of porous materials. NH<inf>4</inf>ZnPO<inf>4</inf> exhibited excellent cycling performance due to its reusability, which is regenerated by releasing NH<inf>3</inf> from NH<inf>4</inf>Zn(NH<inf>3</inf>)PO<inf>4</inf> when heated in air at ≈100 °C. Taking inspiration from previously used and familiar fertilizers further extends this new area of innovative materials that can be used for the reversible storage of low-molecular-weight gases.

DOI： 10.1002/admi.202400729

Web of Science

Scopus

Covalent functionalization of transition metal dichalcogenides with perylene for light harvesting devices 査読有り国際共著国際誌

Canton-Vitoria, R; Matsunaga, Y; Zhang, SC; Xue, MS; Osada, M; Kitaura, R

NANOSCALE 17 巻 ( 13 ) 頁： 8084 - 8100 2025年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nanoscale

This study investigates the optical and electronic properties of eight two-dimensional transition metal chalcogenides (TMDs)—MoS<inf>2</inf>, WS<inf>2</inf>, MoSe<inf>2</inf>, WSe<inf>2</inf>, MoTe<inf>2</inf>, WTe<inf>2</inf>, MoO<inf>2</inf>, and WO<inf>2</inf>—covalently functionalized with perylene, forming zero-dimensional/two-dimensional hybrid materials. Comprehensive characterization was conducted using techniques including XPS, Raman, EDX, TEM, and AFM. Optical properties were assessed using UV-Vis-NIR absorption and photoluminescence spectroscopy, while electronic properties were examined through cyclic voltammetry and field-effect transistor devices. Notably, the spectroscopic signatures of isolated perylene predominate in the hybrid materials, while WSe<inf>2</inf> and MoSe<inf>2</inf> displayed a novel band in the near-IR region, and MoTe<inf>2</inf> exhibited enhanced conductivity. Perylene significantly boosted absorption between 400-600 nm, leading to remarkable improvements in the photo-response and responsivities showing values exceeding 2 × 105% and 2 × 104 mA W−1, respectively. The presented hybrid materials rival the best examples of non-covalent functionalization, underscoring the potential of covalent functionalization as a powerful technique for further tailoring the optical and electronic properties of 2D materials.

DOI： 10.1039/d4nr05364h

Web of Science

Scopus

PubMed

Mechanical exfoliation of non-van der Waals solids: a study of layered perovskite ferroelectric CsPb2Nb3O10 査読有り国際誌

Shimada, M; Li, Y; Kobayashi, M; Yamamoto, E; Canton-Vitoria, R; Osada, M

CHEMISTRY LETTERS 54 巻 ( 2 ) 頁： upaf006 2025年2月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemistry Letters

Mechanical exfoliation of layered materials is one of the most effective methods for obtaining 2D nanosheets. However, this approach is still limited to van der Waals (vdW) layered materials, where interlayer interactions are governed by weak vdW forces. In this study, we used a layered perovskite ferroelectric (CsPb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf>) as a model system to explore the mechanical exfoliation behavior of ionically bonded non-vdW layered materials. Due to the relatively weak out-of-plane bonds involving the interlayer Cs+ ions, CsPb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> could be cleaved into ultrathin sheets with thicknesses ranging from 7.5 to 50 nm. Using piezoresponse force microscopy, we investigated the thickness-dependent ferroelectric properties of CsPb<inf>2</inf>Nb<inf>3</inf>O<inf>10</inf> nanosheets.

DOI： 10.1093/chemle/upaf006

Web of Science

Scopus

その他リンク： https://academic.oup.com/chemlett/article-pdf/54/2/upaf006/61648459/upaf006.pdf

Hetero-assembly and electronic applications of 2D oxide nanosheets 招待有り査読有り Open Access

Osada Minoru

JSAP Review 2025 巻 ( 0 ) 頁： 250211 2025年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Applied Physics

Two-dimensional (2D) nanosheets, which possess atomic or molecular thicknesses and infinite lateral dimensions, have received increasing attention owing to their unique physicochemical properties distinct from those of their bulk counterparts. In particular, the discovery of graphene has facilitated investigations into the intriguing properties of other layered and non-layered 2D nanosheets. Among these 2D nanosheets, 2D oxide nanosheets are an important target owing to their diverse chemical compositions, structures, and functionalities beyond graphene. Herein, I review recent advances in the synthesis, assembly, and properties of 2D oxide nanosheets, highlighting emerging functionalities in electronic applications.

DOI： 10.11470/jsaprev.250211

Open Access

CiNii Research

Ferroelectricity in CsPb2Nb3O10 and exfoliated 2D nanosheets 査読有り

Li, Y; Shimada, M; Kobayashi, M; Yamamoto, E; Canton-Vitoria, R; Liu, XY; Osada, M

DALTON TRANSACTIONS 2024年9月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Dalton Transactions

Pb-based perovskites play pivotal roles in ferroelectric research. In the search for new Pb-based ferroelectrics, we investigated the ferroelectric properties of Dion-Jacobson type CsPb2Nb3O10 and exfoliated 2D nanosheets. Ferroelectricity in CsPb2Nb3O10 was demonstrated for the first time. CsPb2Nb3O10 adopted a polar tetragonal structure with a modest TC = 260 °C and polarization PS = 7.93 μC cm−2; the polarization mainly arose from the out-of-plane displacements of Nb5+ ions and nearby oxygens. CsPb2Nb3O10 layered perovskite offers additional advantages for tailoring ferroelectric nanomaterials, as exfoliated 2D nanosheets provide novel platforms for investigating ferroelectric properties down to the 2D limit. Piezoresponse force microscopy confirmed stable ferroelectricity even in exfoliated 2D Pb2Nb3O10 nanosheets.

DOI： 10.1039/d4dt02343a

Web of Science

Scopus

PubMed

Synthesis of Gold Nanoparticles Using Au(OH)₃ as a Precursor in Aqueous Media 査読有り

スマートプロセス学会誌 13 巻 ( 4 ) 頁： 200 - 204 2024年7月

Autonomous Light Intensity Adaptation in an Energy-Efficient Retinomorphic Organic Ferroelectric Neuristor 査読有り国際共著

Li, LF; Dai, QY; Li, YT; Pei, MJ; Osada, M; Li, Y

ADVANCED OPTICAL MATERIALS 2024年3月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Advanced Optical Materials

In biological visual systems, retina with bidirectional photoresponse can adapt to variable environments and modulate their photosensitivity dependent on illumination conditions in an energy-efficient way. However, to emulate the visual functionality, current systems still require a sustained power supply and manipulate the electrical stimulation manually according to light intensity, thus incurring high energy consumption and the lack of autonomous adaptive function. Herein, an organic ferroelectric neuristor emulating the visual self-adaptation function of retina is introduced. Such autonomous adaptive behavior of device originates from the trap-assisted ferroelectric polarization reversal under light illumination. It allows to realize bidirectional photoresponse in a single device according to light intensity, thus breaking through the limitation of commonly adaptive devices with single photoresponse mechanisms. In particular, only a single gate voltage pulse with an ultralow energy consumption of ≈34 pJ is required to accomplish the adaptation behavior, endowing the visual perception with high autonomy and power efficiency. Finally, the application potential of the neuristor in image pre-processing and recognition under bright and dim light conditions is demonstrated. Therefore, this work opens up a path for the development of retina-like visual systems with highly energy efficient.

DOI： 10.1002/adom.202303172

Web of Science

Scopus

　前のページ - 次のページ　

<長田 実>

論文 - 長田 実

<長田　実>

論文 - 長田　実