Characteristics of Ag-doped LaMnO3 perovskite oxide and its application as a solid oxide fuel cell cathode


Reversible Tetrahedral-site Migration Inducing an Additional Charge Compensation Reaction in Li-rich Layered Oxide 0.4Li2MnO30.6LiNi0.5Mn0.5O2


Variable Photoluminescence Intensity Ratio with the Excitation Wavelength in Eu3+-Doped Perovskite-Type Alkaline Earth ZirconatesPossibility of a Unique Visualization of Ultraviolet Light

Photoluminescence (PL) spectra arising from 4f-4f dipole transitions of Eu doped at both the and sites of perovskite-type alkaline earth zirconates obtained at various excitation wavelengths were evaluated. Changes in the excitation wavelength caused obvious differences in the PL intensity ratio of the induced electric dipole (ED) D → F transition to the magnetic dipole (MD) D → F transition for Eu-doped SrZrO and CaZrO, in which only the B site had a center of symmetry. Two charge transfer (CT) bands associated with the excitation of Eu were observed in the spectra of these oxide samples, which arose from the difference in the electronic structure of the Eu-O coordination at the A and B sites. We conclude that simultaneous Eu substitution at sites with and without a center of symmetry, which have different charge transfer energies, induced the observed novel PL changes with a changing excitation wavelength. Our results may enable the development of a new type of ultraviolet light detector.


Development of silver nanocubes created by pulsed laser ablation in liquid

International Journal of Modern Physics B


Characterization of Ca-doped YCoO3 Perovskite-type oxide as cathode for solid oxide fuel cells


B-Site Mixing Effect on the Redox Reaction of Mn Ions in Perovskite-Type SrFe1-xMnxO3-δ


A flow-based enzyme-free biosensor fabricated using track-etched membrane electrodes: Selective and sensitive detection of uric acid


Composite phosphor of a self-organized silica mixed YAG: Ce


超音波法による全固体電気化学デバイス用固体イオニクス材料の弾性率評価

超音波法による全固体電気化学デバイス用固体イオニクス材料の弾性率評価


Adaptive Cation Pillar Effects Achieving High Capacity in Li-Rich Layered Oxide, Li2MnO3-LiMeO2 (Me = Ni, Co, Mn)

Intensive research is underway to further enhance the performance of lithium-ion batteries (LIBs). To increase the capacity of positive electrode materials, Li-rich layered oxides (LLO) are attracting attention but have not yet been put to practical use. The structural mechanisms through which LLO materials exhibit higher capacity than conventional materials remain unclear because their disordered phases make it difficult to obtain structural information by conventional analysis. The X-ray total scattering analysis reveals a disordered structure consisting of metal ions in octahedral and tetrahedral sites of Li layers as a result of cation mixing after the extraction of Li ions. Metal ions in octahedral sites act as rigid pillars. The metal ions move to the tetrahedral site of the Li layer, which functions as a Li-layer pillar during Li extraction, and returns to the metal site during Li insertion, facilitating Li diffusion as an adaptive pillar. Adaptive pillars are the specific structural features that differ from those of the conventional layered materials, and their effects are responsible for the high capacity of LLO materials. An essential understanding of the pillar effects will contribute to design guidelines for intercalation-type positive electrodes for next-generation LIBs.


Oxygen desorption properties of perovskite-type SrFe1xCoxO3δ: B-site mixing effect on the reduction properties of Fe and Co ions


Enhanced quantum efficiency of a self-organized silica mixed red phosphor CaAlSiN3:Eu


Local electronic and atomic structures of the mixed B-site ions in SrFe1-xMnxO3-δ studied with X-ray absorption spectroscopy


Effects of Crystal Host Structure on Oxygen Desorption Behavior in Perovskite-type AeFe0.9In0.1O3-δ (Ae = Sr, Ba)


Characteristics of YCoO3-type perovskite oxide and application as an SOFC cathode

Journal of Materials Chemistry. A, Materials for Energy and Sustainability


Relationship among the local structure, chemical state of Fe ions in Fe-O polyhedra, and electrical conductivity of cubic perovskite Ba1xSrxFe0.9In0.1O3δ with varying number of oxide ion vacancies


In situ evaluation of the electronic/local structure in B-site mixed perovskite-type oxide SrFe0.6Mn0.4O3δ


Disordered Cubic Spinel Structure in the Delithiated Li2MnO3 Revealed by Difference Pair Distribution Function Analysis


Relationship between rate performance and electronic/structural changes during oxygen redox of lithium-rich 4d/3d transition metal oxides


Evaluation of oxygen contribution on delithiation process of Li-rich layered 3d transition metal oxides


Electronic state analysis of Li2RuO3 positive electrode for lithium ion secondary battery


Relationship between oxygen desorption and the reduction features of Mn and Fe in perovskite-type SrFe1xMnxO3δ


Evaluation of the Electronic and Local Structure of Mn in Proton-Conducting Oxide, Ca(Zr,Mn)O3-δ, to Elucidate a Direct Hydrogen-Dissolution Reaction


Defect chemical studies on oxygen release from the Li-rich cathode material Li1.2Mn0.6Ni0.2O2δ


Strain-Induced Stabilization of Charged State in Li-Rich Layered Transition-Metal Oxide for Lithium-Ion Batteries


High temperature degradation mechanism of a red phosphor, CaAlSiN3:Eu for solid-state lighting


Direct observation of layered-to-spinel phase transformation in Li2MnO3 and the spinel structure stabilised after the activation process


Quantitative Analysis of Transition-Metal Migration Induced Electrochemically in Lithium-Rich Layered Oxide Cathode and Its Contribution to Properties at High and Low Temperatures


Direct observation of reversible oxygen anion redox reaction in Li-rich manganese oxide, Li2MnO3, studied by soft X-ray absorption spectroscopy


Charge compensation analysis of Li-rich layered oxide positive electrode using X-ray absorption fine structure measurement in the soft X-ray region

軟X 線XAFS によるリチウム過剰層状酸化物正極の電荷補償機構解析

Advances in X-Ray Chemical Analysis, Japan


Roles of transition metals interchanging with lithium in electrode materials

Roles of antisite transition metals interchanging with Li atoms in electrode materials of Li transition-metal complex oxides were clarified using a newly developed direct labeling method, termed powder diffraction anomalous fine structure (P-DAFS) near the Ni K-edge. We site-selectively investigated the valence states and local structures of Ni in Li0.89Ni1.11O2, where Ni atoms occupy mainly the NiO2 host-layer sites and partially the interlayer Li sites in-between the host layers, during electrochemical Li insertion/extraction in a lithium-ion battery (LIB). The site-selective X-ray near edge structure evaluated via the P-DAFS method revealed that the interlayer Ni atoms exhibited much lower electrochemical activity as compared to those at the host-layer site. Furthermore, the present analyses of site-selective extended X-ray absorption fine structure performed using the P-DAFS method indicates local structural changes around the residual Ni atoms at the interlayer space during the initial charge; it tends to gather to form rock-salt NiO-like domains around the interlayer Ni. The presence of the NiO-like domains in the interlayer space locally diminishes the interlayer distance and would yield strain energy because of the lattice mismatch, which retards the subsequent Li insertion both thermodynamically and kinetically. Such restrictions on the Li insertion inevitably make the NiO-like domains electrochemically inactive, resulting in an appreciable irreversible capacity after the initial charge but an achievement of robust linkage of neighboring NiO2 layers that tend to be dissociated without the Li occupation. The P-DAFS characterization of antisite transition metals interchanging with Li atoms complements the understanding of the detailed charge-compensation and degradation mechanisms in the electrode materials.


Structural modification by adding Li cations into Mg/Cs-TFSA molten salt facilitating Mg electrodeposition


Direct observation of reversible charge compensation by oxygen ion in Li-rich manganese layered oxide positive electrode material, Li1.16Ni0.15Co0.19Mn0.50O2


Revisit to Diffraction Anomalous Fine Structure (DAFS)

The diffraction anomalous fine structure (DAFS) method that is a spectroscopic analysis combined with resonant X-ray diffraction enables the determination of the valence state and local structure of a selected element at a specific crystalline site and/or phase. This method has been improved by using a polycrystalline sample, channel-cut monochromator optics with an undulator synchrotron radiation source, an area detector and direct determination of resonant terms with a logarithmic dispersion relation. This study makes the DAFS method more convenient and saves a large amount of measurement time in comparison with the conventional DAFS method with a single crystal. The improved DAFS method has been applied to some model samples, Ni foil and Fe3O4 powder, to demonstrate the validity of the measurement and the analysis of the present DAFS method.


Three-dimensional nano electrode by metal nanowire nonwoven clothes

Metal nanowire nonwoven cloth (MNNC) is a metal sheet that has resulted from intertwined metal nanowires 100 nm in diameter with several dozen micrometers of length. Thus, it is a new metallic material having both a flexibility of the metal sheet and a large specific surface area of the nanowires. As an application that utilizes these properties, we propose a high-cyclability electrode for Li storage batteries, in which an active material is deposited or coated on MNNC. The proposed electrode can work without any binders, conductive additives, and current collectors, which might largely improve a practical gravimetric energy density. Huge electrode surfaces provide efficient ion/electron transports, and sufficient interspaces between the respective nanowires accommodate large volume expansions of the active material. To demonstrate these advantages, we have fabricated a NiO-covered nickel nanowire nonwoven cloth (NNNC) by electroless deposition under a magnetic field and annealing in air. The adequately annealed NNNC was shown to be an excellent conversion-type electrode that exhibits a quite high cyclability, 500 mAh/g at 1 C after 300 cycles, compared to that of a composite electrode consisting of NiO nanoparticles. Thus, the present design concept will contribute to a game-changing technology in future lithium ion battery (LIB) electrodes.


Electrochemical behavior of magnesium alloys in alkali metal-TFSA ionic liquid for magnesium-battery negative electrode


A new aspect of chevrel compounds as positive electrodes for magnesium batteries

Journal of Materials Chemistry. A, Materials for Energy and Sustainability


In situ two-dimensional micro-imaging XAFS with CCD detector


Charge compensation mechanisms in Li1.16Ni0.15Co0.19Mn0.50O2 positive electrode material for Li-ion batteries analyzed by a combination of hard and soft X-ray absorption near edge structure


Elastically constrained phase-separation dynamics competing with charge process in LiFePO4/FePO4 system


An X-ray Absorption Spectroscopic Study on Mixed Conductive La0.6Sr0.4Co0.8Fe0.2O3- Cathodes I. Electrical Conductivity and Electronic Structure

The electrical conduction mechanism of mixed conductive perovskite oxides, La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ), for cathode materials of solid oxide fuel cells has been investigated from electronic structural changes during oxygen vacancy formation. La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ) was annealed under various oxygen partial pressures p(O(2))s at 1073 K and quenched. Iodometric titration indicated that the oxygen nonstoichiometry of La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ) depended on the annealing p(O(2)), with more oxygen vacancies introduced at lower than at higher p(O(2))s. X-Ray absorption spectroscopic measurements were performed at the O K-, Co L-, Fe L-, Co K-, and Fe K-edges. The valence states of the Co and Fe ions were investigated by the X-ray absorption near edge structure (XANES) at the Co and Fe L(III)-edges. While the Fe average valence was almost constant, the valence of the Co ions decreased with oxygen vacancy introduction. The O K-edge XANES spectra indicated that electrons were injected into the Co 3d/O 2p hybridization state with oxygen vacancy introduction. Both absorption edges at the Co and Fe K-edge XANES shifted towards lower energies with oxygen vacancy introduction. The shift at the Co K-edge resulted from the decrease in the Co average valence and that at the Fe K-edge appeared to be caused by changes in the coordination environment around the Fe ions. The total conductivity of La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ) decreased with decreasing p(O(2)), due to a decreasing hole concentration.


In situ two-dimensional imaging quick-scanning XAFS with pixel array detector

Quick-scanning X-ray absorption fine structure (XAFS) measurements were performed in transmission mode using a PILATUS 100K pixel array detector (PAD). The method can display a two-dimensional image for a large area of the order of a centimetre with a spatial resolution of 0.2 mm at each energy point in the XAFS spectrum. The time resolution of the quick-scanning method ranged from 10 s to 1 min per spectrum depending on the energy range. The PAD has a wide dynamic range and low noise, so the obtained spectra have a good signal-to-noise ratio.


Electrical conductivity and chemical diffusion in Perovskite-type proton conductors in H2H2O gas mixtures


Nanoscale Observation of the Electronic and Local Structures of LiCoO2 Thin Film Electrode by Depth-Resolved X-ray Absorption Spectroscopy

The Journal of Physical Chemistry Letters


X-ray Absorption Spectroscopic Study on La0.6Sr0.4CoO3-δ Cathode Materials Related with Oxygen Vacancy Formation


Local structural analysis for oxide ion transport in La0.6Sr0.4FeO3-δ Cathodes


Thickness estimation of interface films formed on Li1-xCoO2 electrodes by hard X-ray photoelectron spectroscopy


Defect structure analysis of proton-oxide ion mixed conductor BaCe0.9Nd0.1O3 - δ


Reaction kinetics on platinum electrode / yttrium-doped barium cerate interface under H2H2O atmosphere


Defect structure analysis of B-site doped perovskite-type proton conducting oxide BaCeO3 Part 1: The defect concentration of BaCe0.9M0.1O3-δ (M = Y and Yb)


Defect structure analysis of B-site doped perovskite-type proton conducting oxide BaCeO3: Part 2: The electrical conductivity and diffusion coefficient of BaCe0.9Y0.1O3-δ


Oxygen nonstoichiometry of the perovskite-type oxides BaCe0.9M0.1O3 - δ (M Y, Yb, Sm, Tb, and Nd)


Oxygen nonstoichiometry and defect structure analysis of B-site mixed perovskite-type oxide (La, Sr)(Cr, M)O3 (M=Ti, Mn and Fe)


Oxygen nonstoichiometry of B-site doped LaCrO3


Fuel Cell System for Two-Wheeled Vehicles


Functions of low crystallinity in lithium-rich positive electrode


リチウム過剰系正極材料の低結晶性の機能


リチウムイオン二次電池の次世代高容量正極材料

リチウムイオン二次電池の次世代高容量正極材料


Development of powder diŠraction anomalous fine structure method and applications to electrode materials for rechargeable batteries

P-DAFS 法の開発と蓄電池正極材料への応用

Journal of japanese society for synchroton radiation research


Photoluminescence Property of Nano Silica Mixed YAG:Ce Phosphors

The 3rd International Conference on Nanomaterials and Advanced CompositesProceedings of NAC 2022,Springer Proceedings in Physics


Electrochemical Oxidation of CO in a CO-CO2 System at the Interface of Ni Grid Electrode/ YSZ Electrolyte