Faculty Profiles - OSADA Minoru

Tunable Chemical Coupling in Two-Dimensional van der Waals Electrostatic Heterostructures.

Nitrogen doped ultrathin calcium/sodium niobate perovskite nanosheets for photocatalytic water oxidation Reviewed International journal

Khan Muhammad Shuaib, Diao Zhidan, Osada Minoru, Shen Shaohua

SOLAR ENERGY MATERIALS AND SOLAR CELLS Vol. 205 2020.2

UV degradation mechanism of TiO2-based perovskite solar cells studied by pump-probe spectroscopy Reviewed International journal

Luo Chih-Wei, Thilakan Anusha Puliparambil, Li Jia-Xin, Chen Tzu-Pei, Li Shao-Sian, Chen Chun-Wei, Yabushita Atsushi, Osada Minoru, Tsukagoshi Kazuhito, Sasaki Takayoshi

PHOTONICS FOR SOLAR ENERGY SYSTEMS VIII Vol. 11366 2020

Taniguchi T, Li S, Nurdiwijayanto L, Kobayashi Y, Saito T, Miyata Y, Obata S, Saiki K, Yokoi H, Watanabe K, Taniguchi T, Tsukagoshi K, Ebina Y, Sasaki T, Osada M

ACS nano 2019.10

Wafer-scale and deterministic patterned growth of monolayer MoS(2)via vapor-liquid-solid method

Li Shisheng, Lin Yung-Chang, Liu Xu-Ying, Hu Zehua, Wu Jing, Nakajima Hideaki, Liu Song, Okazaki Toshiya, Chen Wei, Minari Takeo, Sakuma Yoshiki, Tsukagoshi Kazuhito, Suenaga Kazu, Taniguchi Takaaki, Osada Minoru

NANOSCALE Vol. 11 ( 34 ) page： 16122-16129 2019.9

Dielectric nanosheet modified plasmonic-paper as highly sensitive and stable SERS substrate and its application for pesticides detection.

Mekonnen ML, Chen CH, Osada M, Su WN, Hwang BJ

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 225 page： 117484 2019.8

Controlled Assembly of Inorganic Nanosheets and Its Application to High-Performance Metamaterials Reviewed

OSADA Minoru, TANIGUCHI Takaaki, SASAKI Takayoshi

Journal of The Surface Finishing Society of Japan Vol. 70 ( 7 ) page： 355 - 358 2019.7

Origin of Extended UV Stability of 2D Atomic Layer Titania-Based Perovskite Solar Cells Unveiled by Ultrafast Spectroscopy

Thilakan Anusha Puliparambil, Li Jia-Xing, Chen Tzu-Pei, Li Shao-Sian, Chen Chun-Wei, Osada Minoru, Tsukagoshi Kazuhito, Sasaki Takayoshi, Yabushita Atsushi, Wu Kaung-Hsiung, Luo Chih-Wei

ACS APPLIED MATERIALS & INTERFACES Vol. 11 ( 24 ) page： 21473-21480 2019.6

Enhanced oxide-ion conductivity of solid-state electrolyte mesocrystals

Tsukiyama Keishi, Takasaki Mihiro, Kitamura Naoto, Idemoto Yasushi, Oaki Yuya, Osada Minoru, Imai Hiroaki

NANOSCALE Vol. 11 ( 10 ) page： 4523-4530 2019.3

酸化物ナノシートの液相合成と機能材料への応用

長田実

ファインケミカル Vol. 48 page： 28 - 33 2019

Extra-Large Mechanical Anisotropy of a Hydrogel with Maximized Electrostatic Repulsion between Cofacially Aligned 2D Electrolytes Reviewed

Sano Koki, Arazoe Yuka Onuma, Ishida Yasuhiro, Ebina Yasuo, Osada Minoru, Sasaki Takayoshi, Hikima Takaaki, Aida Takuzo

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 57 ( 38 ) page： 12508 - 12513 2018.9

High areal capacitance and rate capability using filled Ni foam current collector Reviewed

Zheyin Yu, Zhenxiang Cheng, George Tsekouras, Xiaolin Wang, Xiangyang Kong, Minoru Osada, Shi Xue Dou

Electrochimica Acta Vol. 281 page： 761 - 768 2018.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Ltd

A novel approach to achieving high areal capacitance and rate capability is demonstrated, whereby an active material is loaded onto a high surface area, filled Ni foam current collector. Micro/nano Ni-filled Ni foam (MNFNF) current collector was fabricated by initially filling commercial Ni foam with Ni slurry and sintering to yield micro Ni-filled Ni foam, followed by electrochemical deposition of nano Ni. This current collector has a greatly enhanced surface area compared to Ni foam, allowing for high mass loading of active material and thereby high areal capacitance and rate capability. Using NiCo2O4 prepared via hydrothermal reaction followed by annealing as the active material, an outstanding areal capacitance of 29.4 F cm-2 at 5 mA cm−2 discharge was achieved, while a high 80% of this capacitance (i.e. 23.5 F cm−2) was retained at 50 mA cm−2 discharge, ascribed to the high surface area and high conductivity of the MNFNF current collector. Regarding stability, only a 2% decrease in areal capacitance after 1000 charge/discharge cycles was observed. The approach employed here might be used to enhance the performance of other active materials besides NiCo2O4.

DOI： 10.1016/j.electacta.2018.06.007

Multifield Control of Domains in a Room-Temperature Multiferroic 0.85BiTi0.1Fe0.8Mg0.1O3-0.15CaTiO3 Thin Film Reviewed

Tingting Jia, Ziran Fan, Junxiang Yao, Cong Liu, Yuhao Li, Junxi Yu, Bi Fu, Hongyang Zhao, Minoru Osada, Ehsan Nasr Esfahani, Yaodong Yang, Yuanxu Wang, Jiang-Yu Li, Hideo Kimura, Zhenxiang Cheng

ACS Applied Materials and Interfaces Vol. 10 ( 24 ) page： 20712 - 20719 2018.6

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society

Single-phase materials that combine electric polarization and magnetization are promising for applications in multifunctional sensors, information storage, spintronic devices, etc. Following the idea of a percolating network of magnetic ions (e.g., Fe) with strong superexchange interactions within a structural scaffold with a polar lattice, a solid solution thin film with perovskite structure at a morphotropic phase boundary with a high level of Fe atoms on the B site of perovskite structure is deposited to combine both ferroelectric and ferromagnetic ordering at room temperature with magnetoelectric coupling. In this work, a 0.85BiTi0.1Fe0.8Mg0.1O3-0.15CaTiO3 thin film has been deposited by pulsed laser deposition (PLD). Both the ferroelectricity and the magnetism were characterized at room temperature. Large polarization and a large piezoelectric effective coefficient d33 were obtained. Multifield coupling of the thin film has been characterized by scanning force microscopy. Ferroelectric domains and magnetic domains could be switched by magnetic field (H), electric field (E), mechanical force (F), and, indicating that complex cross-coupling exists among the electric polarization, magnetic ordering and elastic deformation in 0.85BiTi0.1Fe0.8Mg0.1O3-0.15CaTiO3 thin film at room temperature. This work also shows the possibility of writing information with electric field, magnetic field, and mechanical force and then reading data by magnetic field. We expect that this work will benefit information applications.

DOI： 10.1021/acsami.8b05289

Vapour-liquid-solid growth of monolayer MoS2 nanoribbons Reviewed

Shisheng Li, Yung-Chang Lin, Wen Zhao, Jing Wu, Zhuo Wang, Zehua Hu, Youde Shen, Dai-Ming Tang, Junyong Wang, Qi Zhang, Hai Zhu, Leiqiang Chu, Weijie Zhao, Chang Liu, Zhipei Sun, Takaaki Taniguchi, Minoru Osada, Wei Chen, Qing-Hua Xu, Andrew Thye Shen Wee, Kazu Suenaga, Feng Ding, Goki Eda

Nature Materials Vol. 17 ( 6 ) page： 535 - + 2018.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Nature Publishing Group

Chemical vapour deposition of two-dimensional materials typically involves the conversion of vapour precursors to solid products in a vapour-solid-solid mode. Here, we report the vapour-liquid-solid growth of monolayer MoS2, yielding highly crystalline ribbons with a width of few tens to thousands of nanometres. This vapour-liquid-solid growth is triggered by the reaction between MoO3 and NaCl, which results in the formation of molten Na-Mo-O droplets. These droplets mediate the growth of MoS2 ribbons in the 'crawling mode' when saturated with sulfur. The locally well-defined orientations of the ribbons reveal the regular horizontal motion of the droplets during growth. Using atomic-resolution scanning transmission electron microscopy and second harmonic generation microscopy, we show that the ribbons are grown homoepitaxially on monolayer MoS2 with predominantly 2H- or 3R-type stacking. Our findings highlight the prospects for the controlled growth of atomically thin nanostructure arrays for nanoelectronic devices and the development of unique mixed-dimensional structures.

DOI： 10.1038/s41563-018-0055-z

Chemical synthesis of porous barium titanate thin film and thermal stabilization of ferroelectric phase by porosity-induced strain Reviewed

Norihiro Suzuki, Minoru Osada, Motasim Billah, Yoshio Bando, Yusuke Yamauchi, Shahriar A. Hossain

Journal of Visualized Experiments Vol. 2018 ( 133 ) 2018.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Visualized Experiments

Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

DOI： 10.3791/57441

Self-sensitization and photo-polymerization of diacetylene molecules self-assembled on a hexagonal-boron nitride nanosheet Reviewed

Elisseos Verveniotis, Yuji Okawa, Kenji Watanabe, Takashi Taniguchi, Takaaki Taniguchi, Minoru Osada, Christian Joachim, Masakazu Aono

Polymers Vol. 10 ( 2 ) 2018.2

Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI AG

Long poly-diacetylene chains are excellent candidates for planar, on-surface synthesized molecular electronic wires. Since hexagonal-Boron Nitride (h-BN) was identified as the best available atomically flat insulator for the deposition of poly-diacetylene precursors, we demonstrate the polymerization patterns and rate on it under UV-light irradiation, with subsequent polymer identification by atomic force microscopy. The results on h-BN indicate self-sensitization which yields blocks comprised of several polymers, unlike on the well-studied graphite/diacetylene system, where the polymers are always isolated. In addition, the photo-polymerization proceeds at least 170 times faster on h-BN, where it also results in longer polymers. Both effects are explained by the h-BN bandgap, which is larger than the diacetylene electronic excitation energy, thus allowing the transfer of excess energy absorbed by polymerized wires to adjacent monomers, triggering their polymerization. This work sets the stage for conductance measurements of single molecular poly-diacetylene wires on h-BN.

DOI： 10.3390/polym10020206

Self-Assembly Atomic Stacking Transport Layer of 2D Layered Titania for Perovskite Solar Cells with Extended UV Stability Reviewed

Tzu-Pei Chen, Chung-Wei Lin, Shao-Sian Li, Yung-Han Tsai, Cheng-Yen Wen, Wendy Jessica Lin, Fei-Man Hsiao, Ya-Ping Chiu, Kazuhito Tsukagoshi, Minoru Osada, Takayoshi Sasaki, Chun-Wei Chen

Advanced Energy Materials Vol. 8 ( 2 ) 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley-VCH Verlag

A novel atomic stacking transporting layer (ASTL) based on 2D atomic sheets of titania (Ti1−δO2) is demonstrated in organic–inorganic lead halide perovskite solar cells. The atomically thin ASTL of 2D titania, which is fabricated using a solution-processed self-assembly atomic layer-by-layer deposition technique, exhibits the unique features of high UV transparency and negligible (or very low) oxygen vacancies, making it a promising electron transporting material in the development of stable and high-performance perovskite solar cells. In particular, the solution-processable atomically thin ASTL of 2D titania atomic sheets shows superior inhibition of UV degradation of perovskite solar cell devices, compared to the conventional high-temperature sintered TiO2 counterpart, which usually causes the notorious instability of devices under UV irradiation. The discovery opens up a new dimension to utilize the 2D layered materials with a great variety of homostructrual or heterostructural atomic stacking architectures to be integrated with the fabrication of large-area photovoltaic or optoelectronic devices based on the solution processes.

DOI： 10.1002/aenm.201701722

Nanoarchitectonics in dielectric/ferroelectric layered perovskites: From bulk 3D systems to 2D nanosheets Reviewed

Minoru Osada, Takayoshi Sasaki

Dalton Transactions Vol. 47 ( 9 ) page： 2841 - 2851 2018

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry

We present an overview of recent investigations on the dielectric/ferroelectric properties of Dion-Jacobson-type perovskites, including bulk 3D layered systems and their exfoliated 2D nanosheets. In contrast to the Ruddlesden-Popper and Aurivillius phases, the Dion-Jacobson phases in bulk 3D systems have not been important targets for constructing dielectric/ferroelectric materials. However, recent investigations on Dion-Jacobson phases have provided new impetus to dielectric/ferroelectric materials. Dion-Jacobson perovskites can also facilitate delamination into 2D nanosheets. Layer-by-layer engineering of 2D perovskite nanosheets has a great potential for the rational design of new high-k dielectric/ferroelectric materials and nanodevices.

DOI： 10.1039/c7dt03719h

Elucidation of structure and conduction mechanism in Nd-Mn substituted Y-type strontium hexaferrites Reviewed

Bashir Ahmad, Muhammad Naeem Ashiq, Muhammad Shuaib Khan, Minoru Osada, Muhammad Najam-Ul-Haq, Irshad Ali

JOURNAL OF ALLOYS AND COMPOUNDS Vol. 723 page： 9 - 16 2017.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

Technologically important ferrites magnetic materials with nominal composition "Sr2-xNdxCo2MnyFe12-yO22" (x = 0.0 to 0.1 and y = 0.0 to 1.0) were fabricated by the simple sol-gel method. The X-ray diffraction analysis endorsed the formation of well-defined Y-type hexagonal single phase with crys-tallite size in range of 38-45 nm. Owing to reduction of Fe3+ ions at octahedral site, an increase in DC resistivity was observed from 4.083 x 10(8) to 2.376 x 10(9) Omega-cm with the increase in substituents content. The two conduction mechanisms operating in ferri- and paramagnetic regions were shown by Arrhenius plot. It was observed that conduction in ferrimagnetic and paramagnetic regions was governed by the hopping of electrons and polarons, respectively. The decrease in Curie temperature "Tc" (553-423 K) was detected as a factor of Nd-Mn content due to decrease in Fe-Fe interaction at octahedral site. The changes in the values of dielectric constant (epsilon'), dielectric loss factor (epsilon") and tan loss (delta) follow Maxwell-Wagner model. The relatively high resistivity (2.376 x 10(9) Omega-cm) and low dielectric constants (2.97 at 1 MHz) for the sample with x = 0.1 and y = 1.0 make this material as an excellent candidates for high frequency microwave devices. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2017.06.219