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：Microscopy  

The charge state of supported metal catalysts is the key to understand the elementary processes involved in catalytic reactions. However, high-precision charge analysis of the metal catalysts at the atomic level is experimentally challenging.To address this critical challenge, high-sensitivity electron holography has recently been successfully applied for precisely measuring the elementary charges on individual platinum nanoparticles supported on a titanium dioxide surface. In this review, we introduce the latest advancements in high-precision charge analysis and discuss the mechanisms of charge transfer at the metal–support interface. The development of charge measurements is entering a new era, and charge analyses under conditions closer to practical working environments, such as real-time, real-space, and reactive gas environments, are expected to be realized in the near future.

DOI： 10.1093/jmicro/dfae018

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Solid State Electrochemistry  

Evaluating ion-conductive solid electrolytes (SEs) accurately is crucial for advancing solid-state battery technology. Scanning/transmission electron microscopy (S/TEM) is a valuable technique for examining the local characteristics of battery materials. However, the tolerance of SEs to high-energy electron beams is notably lower than that of electrode active materials, because SEs generally have low electron conductivity. Here, we propose a specialized coating technique for TEM samples, termed “nano-shield,” which enables stable and accurate observation of their micro-/nano-structures. Nano-shield consists of a dual-layer coating combining an amorphous insulating layer of aluminum oxide (AlOx) with a conductive carbon (C) film. The AlOx layer blocks ion diffusion in the TEM samples, and the C layer minimizes electron charging during electron-beam irradiation. By applying a nano-shield, we successfully visualized the atomic structures of a lithium-ion-conductive SE, Li1.3Al0.3T1.7(PO4)3 (LATP), by using STEM at room temperature. Additionally, we performed a precise elemental analysis of a sodium-ion-conductive SE, Na3Zr2Si2PO12 (NZSP), via STEM equipped with energy-dispersive X-ray spectroscopy (STEM-EDS). Our findings demonstrate that nano-shield enhances the reliability of S/TEM observations of SEs and sheds light on its underlying protective mechanisms.

DOI： 10.1007/s10008-024-05869-8

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その他リンク： https://link.springer.com/article/10.1007/s10008-024-05869-8/fulltext.html

担当区分：筆頭著者,　責任著者  

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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：Microscopy  

Perovskite oxides, ABO3, are potential catalysts for the oxygen evolution reaction, which is important in the production of hydrogen as a sustainable energy resource. Optimizing the chemical composition of such oxides by substitution or doping with additional elements is an effective approach to improving the activity of such catalysts. Here, we characterized the crystal and electronic structures of fluorine-doped La0.5Sr0.5CoO3− particles using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). High-resolution STEM imaging demonstrated the formation of a disordered surface phase caused by fluorine doping. In addition, spatially resolved EELS data showed that fluorine anions were introduced into the interiors of the particles and that Co ions near the surfaces were slightly reduced by fluorine doping in conjunction with the loss of oxygen ions. Peak fitting of energy-loss near-edge structure data demonstrated an unexpected nanostructure in the vicinity of the surface. An EELS characterization comprising elemental mapping together with an energy-loss near-edge structure analysis indicated that this nanostructure could not be assigned to Co-based materials but rather to the solid electrolyte BaF2. Complementary structural and electronic characterizations using STEM and EELS as demonstrated herein evidently have the potential to play an increasingly important role in elucidating the nanostructures of functional materials.

DOI： 10.1093/jmicro/dfad031

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本金属学会  

DOI： 10.2320/materia.63.95

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記述言語：その他   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advanced Functional Materials  

Abstract

Instead of conventional cation doping strategy, anion doping is a promising new strategy for advances of energy conversion and storage technologies such as batteries, catalysts, electrolysis, and fuel cells. To synthesize mixed‐anion compounds, novel synthesis techniques such as topochemical reaction, high‐pressure reaction, solvothermal reaction have been developed. Despite these excellent synthesis techniques, synthesizable mixed‐anion compounds are still limited. For further expansion of the material exploration of mixed‐anion compounds, herein, an electrochemical anion doping technique is developed, which can flexibly control a species of anion, the doping rate and the degree of anion doping. The concept of the new synthesis technique is verified by F doping to the perovskite oxide La_0.5Sr_0.5CoO_3−δ. Quantitative control of F in the perovskite host material is succeeded by using an electrochemical reactor composed of La_0.5Sr_0.5CoO_3−δ‐BaF₂|BaF₂|PbF₂‐Pb, and phase‐pure F‐doped La_0.5Sr_0.5CoO_3−δ powder is obtained. Moreover, nano‐size crystalline domains with amorphous phase are formed on the particle surface under the high‐rate F doping, suggesting that tuning the anion doping rate enables the control of the formation of metastable phase. As demonstrated, the electrochemical anion doping technique opens up new possibilities for advances of energy materials by utilizing function of anionic species.

DOI： 10.1002/adfm.202307116

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：その他   掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Physics Letters  

We grew epitaxial thin films of hematite (α-Fe2O3) on (0 0 0 1) Al2O3 substrates by pulsed laser deposition and investigated their magnetic properties. α-Fe2O3 films grown at lower temperatures are found to undergo the Morin transition at higher temperatures, implying that lowering the growth temperature and managing lattice defects associated with strain relaxation are key to realizing Morin transition. We also characterized films' magnetic properties by spin Hall magnetoresistance (SMR). We show that tri-axial magnetic anisotropy can be detected as SMR features having a 60° period with respect to in-plane magnetic field rotations. Furthermore, a large change in SMR ratio associated with Néel vector re-orientation due to Morin transition is seen. Details of SMR properties for α-Fe2O3 films and their analysis results, including the influence of the fabrication process on SMR behaviors, are discussed.

DOI： 10.1063/5.0087643

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acs.nanolett.1c03143

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.7567/1347-4065/ab4b15

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c9nr00806c

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11410/kenbikyo.54.1_14

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41467-018-04412-4

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ultramic.2017.04.018

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acsami.7b08134

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/nmat4580

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c4dt03749a

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.4918965

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/cg501340e

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/cg500285m

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.4875839

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.7567/APEX.7.015503

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/ma4014934

リポジトリ公開URL： https://hdl.handle.net/2324/7172123

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.4817505

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.4803869

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/adfm.201202402