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5. Magnetic-field-induced spin-crossover transition in [Mn$^{\textrm{III}}$(taa)] studied by X-ray absorption spectroscopy

Author

Her, Jim Long, Matsuda, Yasuhiro H., Nakano, Motohiro, Niwa, Yasuhiro, and Inada, Yasuhiro

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

The X-ray absorption near-edge structure (XANES) of Mn in a spin-crossover compound, [Mn$^{\textrm{III}}$(taa)], was studied in pulsed high magnetic fields up to 37T. By applying magnetic fields to the low-temperature low-spin (LS) state, significant changes in the spectra were observed, suggesting a magnetic-field-induced spin-crossover to the high-spin (HS) state. At low temperatures, the magnetic field dependence of the changes in the spectra exhibited hysteresis. Furthermore, when the magnetic field was set to zero, a considerable remanent component was observed. The energy barrier of the HS $\to$ LS transition was evaluated from the temperature dependence of the decay time of the remanent signal. The energy barrier of the transition was found to be 134K, which is notably lower than that for other spin-crossover compounds reported previously. Since the fraction of the field-induced HS state was at most 30% and the thermodynamic macroscopic field-induced phase transition was expected to occur in fields higher than 55T, the observed field-induced transition at low temperatures down to 17K could be understood as a localized microscopic transition at the single-molecular level., Comment: 14 pages, 7 figures

Published
2010

13. Valence Control of Charge and Orbital Frustrated System YbFe2O4 with Electrochemical Li+ intercalation

Author

Murase, Satoshi, Yoshikawa, Yumi, Kosuke, Fujiwara, Fukada, Yukimasa, Teranishi, Takeshi, Kano, Jun, Fujii, Tatsuo, Inada, Yasuhiro, Katayama, Misaki, Yoshii, Kenji, Tsujii, Takuya, Matsumura, Daiju, Ikeda, Naoshi, Murase, Satoshi, Yoshikawa, Yumi, Kosuke, Fujiwara, Fukada, Yukimasa, Teranishi, Takeshi, Kano, Jun, Fujii, Tatsuo, Inada, Yasuhiro, Katayama, Misaki, Yoshii, Kenji, Tsujii, Takuya, Matsumura, Daiju, and Ikeda, Naoshi

Abstract

We report a trial of the valence control for mixed valence iron triangular oxide YbFe2O4 in order to develop an effective technique to control the frustration of charges in strongly correlated electron systems. The electro-chemical doping of Li+ into YbFe2O4 was examined on the cell type sample similar to the Li-ion secondary battery cell. Systematic change of the lattice constant, Fe-Fe and Fe-Yb distance were observed with Li doping. Maximum value of the doping was over 300 mAh/g. An EXAFS experiment indicated that Li positioned between Yb octahedron layer (U-layer) and Fe-bipyramidal layer (W-layer). However, detailed change of iron valence state of YbFe2O4 was not clearly observed because of the superimpose of the signal from iron metal nano particles in XANES observation. We discuss that the uncertainty might arise from the inhomogeneous distribution of the sample particle size, which might prevent the homogeneous doping of Li because the doping occurs on the surface of each nano-particles.

Published
2022

22. Vanadium diphosphide as a negative electrode material for sodium secondary batteries

Author

Kaushik, Shubham, Matsumoto, Kazuhiko, Orikasa, Yuki, Katayama, Misaki, Inada, Yasuhiro, Sato, Yuta, Gotoh, Kazuma, Ando, Hideka, and Hagiwara, Rika

Subjects
Sodium ion battery, Phosphide, Ionic liquid
Abstract

The abundance of sodium resources has sparked interest in the development of sodium-ion batteries for large-scale energy storage systems, amplifying the need for high-performance negative electrodes. Although transition metal phosphide electrodes have shown remarkable performance and great versatility for both lithium and sodium batteries, their electrochemical mechanisms in sodium batteries, particularly vanadium phosphides, remain largely elusive. Herein, we delineate the performance of VP₂ as a negative electrode alongside ionic liquids in sodium-ion batteries. The polycrystalline VP₂ is synthesized via one-step high energy ball-milling and characterized using X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Electrochemical tests ascertained improved performance at intermediate temperatures, where the initial cycle was conducted at 100 mA g⁻¹ yielded a significantly higher discharge capacity of 243 mAh g⁻¹ at 90°C compared to the limited capacity of 49 mAh g⁻¹ at 25°C. Enhanced rate and cycle performance are also achieved at 90 °C. Electrochemical impedance spectroscopy and scanning electron microscopy further reveal a reduced charge transfer resistance at 90°C and the formation of a uniform and stable solid electrolyte interface (SEI) layer after cycling. X-ray diffraction and nuclear magnetic resonance spectroscopy are used to confirm the conversion-based mechanism forming Na₃P after charging.

Published
2021

23. Vanadium diphosphide as a negative electrode material for sodium secondary batteries

Author

30574016, 30237911, Kaushik, Shubham, Matsumoto, Kazuhiko, Orikasa, Yuki, Katayama, Misaki, Inada, Yasuhiro, Sato, Yuta, Gotoh, Kazuma, Ando, Hideka, Hagiwara, Rika, 30574016, 30237911, Kaushik, Shubham, Matsumoto, Kazuhiko, Orikasa, Yuki, Katayama, Misaki, Inada, Yasuhiro, Sato, Yuta, Gotoh, Kazuma, Ando, Hideka, and Hagiwara, Rika

Abstract

The abundance of sodium resources has sparked interest in the development of sodium-ion batteries for large-scale energy storage systems, amplifying the need for high-performance negative electrodes. Although transition metal phosphide electrodes have shown remarkable performance and great versatility for both lithium and sodium batteries, their electrochemical mechanisms in sodium batteries, particularly vanadium phosphides, remain largely elusive. Herein, we delineate the performance of VP₂ as a negative electrode alongside ionic liquids in sodium-ion batteries. The polycrystalline VP₂ is synthesized via one-step high energy ball-milling and characterized using X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Electrochemical tests ascertained improved performance at intermediate temperatures, where the initial cycle was conducted at 100 mA g⁻¹ yielded a significantly higher discharge capacity of 243 mAh g⁻¹ at 90°C compared to the limited capacity of 49 mAh g⁻¹ at 25°C. Enhanced rate and cycle performance are also achieved at 90 °C. Electrochemical impedance spectroscopy and scanning electron microscopy further reveal a reduced charge transfer resistance at 90°C and the formation of a uniform and stable solid electrolyte interface (SEI) layer after cycling. X-ray diffraction and nuclear magnetic resonance spectroscopy are used to confirm the conversion-based mechanism forming Na₃P after charging.

Published
2021

24. Single atomic Co coordinated with N in microporous carbon for oxygen reduction reaction obtained from Co/2-methylimidazole anchored to Y zeolite as a template

Author

Universidad de Alicante. Departamento de Química Física, Universidad de Alicante. Departamento de Química Inorgánica, Universidad de Alicante. Instituto Universitario de Materiales, Zhu, Yexin, Miyake, Koji, Shu, Yasuhiro, Moroto, Koki, Hirota, Yuichiro, Uchida, Yoshiaki, Tanaka, Shunsuke, Zheng, Tao, Katayama, Misaki, Inada, Yasuhiro, Morallon, Emilia, Cazorla-Amorós, Diego, Kong, Chang Yi, Nishiyama, Norikazu, Universidad de Alicante. Departamento de Química Física, Universidad de Alicante. Departamento de Química Inorgánica, Universidad de Alicante. Instituto Universitario de Materiales, Zhu, Yexin, Miyake, Koji, Shu, Yasuhiro, Moroto, Koki, Hirota, Yuichiro, Uchida, Yoshiaki, Tanaka, Shunsuke, Zheng, Tao, Katayama, Misaki, Inada, Yasuhiro, Morallon, Emilia, Cazorla-Amorós, Diego, Kong, Chang Yi, and Nishiyama, Norikazu

Abstract

Zeolite-templated carbons (ZTCs) composed of curved and single-layer graphene frameworks have uniform micropores (ca. 1.2 nm) and high surface areas (~4,000 m2/g). Owing to their outstanding properties originating from the porous structures, ZTCs have been used in many applications. In this work, we synthesized Co/N-doped ZTC (Co/N-ZTC) by complexing Co ion with 2-methylimidazole in Y zeolite to expand further utilization of ZTCs. The obtained Co/N-ZTC has a high surface area (ca. 2,000 m2/g) and single atomic Co species in CoNx moieties, which actually contributes to its excellent catalytic performance on oxygen reduction reaction. This synthetic concept is beneficial to fabricate single atomic transition metals coordinated with heteroatoms in ZTCs, which contributes to the progress of material design of single atomic catalyst–supported porous materials.

Published
2021

28. Improvement of Cycle Capability of Fe-Substituted Li2S-Based Positive Electrode Materials by Doping with Lithium Iodide

Author

Takeuchi, Tomonari, Kageyama, Hiroyuki, Nakanishi, Koji, Kiuchi, Hisao, Katayama, Misaki, Inada, Yasuhiro, Ohta, Toshiaki, Fukunaga, Toshiharu, Sakaebe, Hikari, Kobayashi, Hironori, and Matsubara, Eiichiro

Subjects
Batteries - Lithium, Lithium sulfur battery, cycle performance, high capacity
Abstract

For an attempt to improve the cycle capability of the Li8FeS5 cells, we have prepared LiI-doped Li8FeS5 composite positive electrode materials. The obtained Li8FeS5·xLiI sample cells showed the improved cycle capability, though the initial capacity value decreased with proportional to the mass of LiI. The improved cycle performance was attributable to the suppressed resistance rise of the cells, due probably to the suppression of high-resistive surface precipitates formed by the reaction between the active material and the electrolyte. The dopant LiI would stabilize the local structure against Li extraction/insertion reactions, as well as suppress the reaction with the electrolyte, leading to the improved cycle performance.

Published
2018

29. Crystalline maricite NaFePO₄ as a positive electrode material for sodium secondary batteries operating at intermediate temperature

Author

Hwang, Jinkwang, Matsumoto, Kazuhiko, Orikasa, Yuki, Katayama, Misaki, Inada, Yasuhiro, Nohira, Toshiyuki, and Hagiwara, Rika

Subjects
Sodium secondary batteries, Intermediate-temperature operation, Olivine, MariciteIonic liquid
Abstract

Maricite NaFePO₄ (m-NaFePO₄) was investigated as a positive electrode material for intermediate-temperature operation of sodium secondary batteries using ionic liquid electrolytes. Powdered m-NaFePO₄ was prepared by a conventional solid-state method at 873 K and subsequently fabricated in two different conditions; one is ball-milled in acetone and the other is re-calcined at 873 K after the ball-milling. Electrochemical properties of the electrodes prepared with the as-synthesized m-NaFePO₄, the ball-milled m-NaFePO₄, and the re-calcined m-NaFePO₄ were investigated in Na[FSA]-[C₂C₁im][FSA] (C₂C₁im⁺ = 1-ethyl-3-methylimidazolium, FSA⁻ = bis(fluorosulfonyl)amide) ionic liquid electrolytes at 298 K and 363 K to assess the effects of temperature and particle size on their electrochemical properties. A reversible charge-discharge capacity of 107 mAh g⁻¹ was achieved with a coulombic efficiency >98% from the 2nd cycle using the ball-milled m-NaFePO₄ electrode at a C–rate of 0.1 C and 363 K. Electrochemical impedance spectroscopy using m-NaFePO₄/m-NaFePO₄ symmetric cells indicated that inactive m-NaFePO₄ becomes an active material through ball-milling treatment and elevation of operating temperature. X-ray diffraction analysis of crystalline m-NaFePO₄ confirmed the lattice contraction and expansion upon charging and discharging, respectively. These results indicate that the desodiation-sodiation process in m-NaFePO₄ is reversible in the intermediate-temperature range.

Published
2018

32. Kinetics and mechanism for the metalation of 5,10,15120-tetrakis(pentafluorophenyl)porphyrin with bis(beta-diketonato)copper(II) complexes in supercritical dioxide and n-hexane

Author

Inada, Yasuhiro, Sato, Hideyuki, Kiu, Shi-jun, Horita, Taichi, and Funahashi, Shigenobu

Subjects
Hexane -- Chemical properties, Copper compounds -- Chemical properties, Porphyrins -- Chemical properties, Chemicals, plastics and rubber industries
Abstract

Incorporation of copper(II) ion into fluorinated porphyrin to form the metalloporphyrin CCu(tpfpp)) was kinetically investigated using bis(beta-diketonato)copper(II) complexes (CuL2) in ScCO2 and n-hexane. The reaction mechanisms in both the solvents seemed to be similar.

Published
2003

38. Mechanistic study of solvent exchange reactions of manganese(II), iron(II), nickel(II), copper(II), and iron(III) ions in bulky 1,1,3,3-tetramethylurea (TMU) solvent by measurements of oxygen-17 NMR relaxation rates and chemical shifts: Complexation reaction of nickel(II) ion in TMU and crystal structure of [Ni(tmu) 5](BPh 4) 2

Author

Tanada, Ken-ichiro, Hashimoto, Akira, Tsuji, Hiroaki, Kato, Kaoru, Inada, Yasuhiro, Aizawa, Sen-ichi, and Funahashi, Shigenobu

Published
2006
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40. In situ time-resolved energy-dispersive X-ray absorption fine structure study on the decarbonylation processes of Mo(CO) (sub)6 entrapped in NaY and HY zeolites

Author

Yamaguchi, Aritomo, Suzuki, Akane, Shido, Takafumi, Inada, Yasuhiro, Asakura, Kiyotaka, Nomura, Masaharu, and Iwasawa, Yasuhiro

Subjects
Chemistry, Physical and theoretical -- Research, Coordination compounds -- Physiological aspects, Zeolites -- Physiological aspects, Yttrium -- Physiological aspects, Sodium -- Physiological aspects, Carbon monoxide -- Physiological aspects, Molybdenum -- Physiological aspects, Carbon -- Physiological aspects, Absorption -- Physiological aspects, Chemicals, plastics and rubber industries
Published
2002

41. Structural characterization and formation kinetics of sitting-atop (SAT) complexes of some porphyrins with copper(II) ion in aqueous acetonitrile relevant to porphyrin metalation mechanism. Structures of aquacopper(II) and Cu(II)-SAT complexes as determined by XAFS spectroscopy

Author

Inamo, Masahiko, Kamiya, Naruhisa, Inada, Yasuhiro, Nomura, Masaharu, and Funahashi, Shigenobu

Subjects
Chemistry, Inorganic -- Research, Porphyrins -- Physiological aspects, Copper -- Physiological aspects, Ions -- Physiological aspects, Acetonitrile -- Physiological aspects, Spectrum analysis -- Usage, Solution (Chemistry) -- Physiological aspects, Chemistry
Abstract

Research has been conducted on the porphyrin sitting-top complexes. The formation of these complexes with the copper(II) ion has been confirmed spectrophotometrically in aqueous acetonitrile and the formation rates determined as the water concentration function have been determined.

Published
2001

44. Solvation structures of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), and gallium(III) ions in methanol, etnanol, dimethyl sulfoxide, and trimethyl phosphate as studied by EXAFS and electronic spectroscopies

Author

Inada, Yasuhiro, Hayashi, Hiroo, Sugimoto, Ken-ichi, and Funahashi, Shigenobu

Subjects
Molecular structure -- Research, Solvation -- Research, Manganese -- Research, Iron -- Research, Cobalt -- Research, Nickel -- Research, Copper -- Research, Zinc -- Research, Gallium -- Research, Methanol -- Research, Alcohol -- Research, Dimethyl sulfoxide -- Research, Chemicals, plastics and rubber industries
Abstract

Extended X-ray absorption fine structure and electronic spectroscopies were used to study the solvation geometries of the Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Ga(III) ions in methanol (MeOH), ethanol (EtOH), dimethyl sulfoxide (DMSO), and trimethyl phosphate (TMP). The solvation geometries and M-O bond lengths of all the metal ions in MeOH, EtOH and DMSO were found to be similar to those in water. However, solvation structure in TMP was different from that in other solvents.

Published
1999

48. Solvation structures and kinetics of solvent exchange reactions of the manganese(II) ion in six nitriles as studied by X-ray diffraction, EXAFS, and NMR techniques

Author

Inada, Yasuhiro, Sugata, Takashi, Ozutsumi, Kazuhiko, and Funahashi, Shigenobu

Subjects
Solvation -- Research, Manganese -- Research, X-ray diffractometer -- Usage, Extended X-ray absorption fine structure -- Usage, Nuclear magnetic resonance spectroscopy -- Usage, Ion exchange -- Research, Chemistry
Abstract

Research was conducted to examine the solvent exchange reactions of the manganese(II) ion in six nitriles with various sizes of the alkyl or aryl substituent. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used in the study of the solvation structures of the manganese(II) ion in propiononitrile, butyronitrile, isobutyronitrile, valeronitrile and benzonitrile. The solvation structure of the manganese(II) ion in methyl cyanide was determined by the X-ray diffraction technique while the EXAFS technique was responsible for determining those in the other nitriles.

Published
1998

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