九州大学 研究者情報
論文一覧
村山 美乃(むらやま はるの) データ更新日:2019.04.16

准教授 /  理学研究院 化学部門


原著論文
1. Koji Suto, Akiyoshi Nakata, Haruno Murayama, Toshiro Hirai, Jun Ichi Yamaki, Zempachi Ogumi, Electrochemical properties of Al/vanadium chloride batteries with AlCl3-1-Ethyl-3-methylimidazolium chloride electrolyte, Journal of the Electrochemical Society, 10.1149/2.0991605jes, 163, 5, A742-A747, 2016.01, [URL], We have studied the electrochemical properties of vanadium chloride in molten salt containing AlCl3 and 1-ethyl-3-methylimmidazolium chloride (EMIC) with a molar ratio of 1.5/1.0 at an ambient temperature using cyclic voltammetry and the X-ray absorption near-edge structure (XANES). Cyclic voltammograms (CVs) of VCl3 contain a pair of oxidation peak at about 1.5 V vs. Al/Al3+ and reduction peak at about 0.9 V vs. Al/Al3+ assigned to the V(3) V(2) reaction and a pair of oxidation peak at about 0.9 V vs. Al/Al3+ and reduction peak at about 0.4 V vs. Al/Al3+ assigned to the V(2) V(0) reaction. The former remains in the CV after reduction and oxidation cycling. On the other hand, the latter disappears from the CV after a couple of cycles. We also investigate the effect of adding fluorobenzene (FB) to the AlCl3-EMIC salts on the solubility and electrochemical properties of VCl3. FB greatly reduces the VCl3 dissolution in the salts and improves capacity retention with reduction and oxidation cycling without change in the reaction process..
2. Tamao Ishida, Zhenzhong Zhang, Haruno Murayama, Makoto Tokunaga, Oxide-supported palladium and gold nanoparticles for catalytic C-H transformations, Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry, 10.5059/yukigoseikyokaishi.75.1150, 75, 11, 1150-1161, 2017.01, [URL], C-H transformations catalyzed by heterogeneous Pd and Au catalysts are disclosed. For palladium, Pd(0), PdO, and Pd(OH) 2 worked as catalytically active species involved in oxidative addition, electrophilic substitution, and concerted metalation deprotonation pathways depending on the reaction under investigation. We also found that Au(0) nanoparticles catalyzed C-H coupling and discuss the difference in catalytic properties between Pd and Au. The role of metal oxide (MO x) supports is also mentioned: MO x not only stabilizes Pd and Au particles but also creates cationic metal sites at the perimeter interface, and these play an important role in activating the substrates..
3. Isao Nakamura, Haruno Murayama, Makoto Tokunaga, Mitsutaka Okumura, Tadahiro Fujitani, Adsorption and thermal reactivity of dimethyl trisulfide on a Au(111) single-crystal surface, Surface Science, 10.1016/j.susc.2018.07.012, 677, 186-192, 2018.11, [URL], We investigated the adsorption and thermal reactivity of dimethyl trisulfide (DMTS, CH3SSSCH3) on a Au(111) single-crystal surface. X-ray photoelectron spectroscopy results indicated that at exposure temperatures of 100–300 K, DMTS dissociatively adsorbed as CH3S and CH3SS. That the dissociative adsorption rate was independent of exposure temperature suggested that DMTS dissociation on Au proceeded without an energy barrier at >100 K. In contrast, the thermal reactions of the adsorbed CH3S and CH3SS varied strongly with formation temperature. Specifically, after CH3S and CH3SS formed on Au(111) at 100 K, increasing the temperature resulted in associative desorption of CH3S as dimethyl disulfide (CH3SSCH3) and coupling reaction of CH3SS to ethane and atomic sulfur. In contrast, after CH3S and CH3SS formed at 150 K, increasing the temperature resulted not only in these two reactions but also in production of dimethyl disulfide and atomic sulfur by reaction between CH3S and CH3SS. At formation temperatures of 200 and 300 K, the only reaction observed was that between CH3S and CH3SS. These results suggest that the surface structure of the adsorbed species formed by DMTS dissociation on Au(111) depended on formation temperature. Specifically, at 100 K, dissociation of DMTS resulted in formation of CH3S and CH3SS islands on the Au(111) surface, whereas the two species were randomly adsorbed at higher formation temperatures..
4. Haruno Murayama, Yusuke Yamamoto, Misaki Tone, Takayuki Hasegawa, Moemi Kimura, Tamao Ishida, Atsuko Isogai, Tsutomu Fujii, Mitsutaka Okumura, Makoto Tokunaga, Selective adsorption of 1,3-dimethyltrisulfane (DMTS) responsible for aged odour in Japanese sake using supported gold nanoparticles, Scientific reports, 10.1038/s41598-018-34217-w, 8, 1, 2018.12, [URL], Gold (Au) nanoparticles (NPs) supported on SiO
2
(Au/SiO
2
) were prepared by a practical impregnation method and applied as an adsorbent for 1,3-dimethyltrisulfane (DMTS), which is responsible for an unpleasant odour in drinks, especially Japanese sake. Compared with a conventional adsorbent, activated carbon, Au/SiO
2
selectively reduced the DMTS concentration in Japanese sake without decreasing the concentrations of other aromatic components. DFT calculations revealed that the selective adsorption of DMTS occurred through the formation of a stable intermediate. The size of the supported Au NPs was controlled by the preparation conditions and determined from TEM observations and XRD measurements, and the size was ranged from 2.4 nm to 30 nm. Au/SiO
2
having Au NPs with a diameter of 2.4 nm adsorbed DMTS the most efficiently. Smaller Au NPs showed better DMTS adsorption capabilities because larger amounts of Au atoms were exposed on their surfaces in the size range of this study. Langmuir-type monolayer adsorption and one-to-one binding of Au–S are proposed to occur based on an adsorption isotherm experiment. Even though significant differences of the fruity aroma score were not observed in the sensory evaluation between Au/SiO
2
and activated carbon for this less aromatic Japanese sake, Au/SiO
2
selectively decreased the DMTS concentration in the instrumental analysis..
5. Zhenzhong Zhang, Tetsuya Mamba, Eiji Yamamoto, Haruno Murayama, Tamao Ishida, Tetsuo Honma, Tadahiro Fujitani, Makoto Tokunaga, Direct transformation of terminal alkenes with H2O into primary alcohols over metal oxide-supported Pd catalysts, Applied Catalysis B: Environmental, 10.1016/j.apcatb.2019.01.031, 246, 100-110, 2019.06, [URL], The anti-Markovnikov addition of H2O to alkenes to directly bring in primary alcohols has been considered one of the “10 challenges in catalysis” in the 1990s, but the challenging issue has still remained unsolved over the past few decades, particularly in terms of developing an atom-efficient synthetic strategy. In this context, we introduce a novel access for the transformation of terminal alkenes with H2O into the corresponding primary alcohols over metal oxide-supported Pd catalysts, employing O2 as the sole oxidant. Direct and efficient synthesis of cinnamyl alcohol from allylbenzene and H2O was initially achieved as a fine chemical example over Pd(NO3)2/CeO2-ZrO2, and the target saturated alcohol (3-phenylpropan-1-ol) was obtained as the anti-Markovnikov selective product from a “one-pot” process using H2 as the reductant. The Pd(NO3)2/CeO2-ZrO2 was characterized by HAADF-STEM, XRD and X-ray absorption fine structure (XAFS) analyses, indicating that the molecular Pd(NO3)2 is probably deposited as it is on the support, which likely plays an important role to promote this reaction. In the second part, Pd(NO3)2/CeO2-ZrO2 and other supported Pd catalysts were applied for the transformation of 1,3-butadiene into 2-butene-1,4-diol in a batch reactor. Besides, butane-1,4-diol, which is an important industrial material, was efficiently produced by the simple hydrogenation of 2-butene-1,4-diol in a “one-pot” manner. Significantly, the development of the reaction catalyzed by supported Pd in a gas flow reactor bestows great potential to further industrial applications. Additionally, the adsorption structure of 1,3-butadiene on Pd(111) was confirmed as the s-trans form by infrared reflection absorption spectroscopy (IRAS) measurements. The change in the electronic states of surface Pd atoms upon oxygen adsorption was observed by X-ray photoelectron spectroscopy (XPS)..
6. Akiyoshi Nakata, Hajime Arai, Haruno Murayama, Katsutoshi Fukuda, Tomokazu Yamane, Toshiro Hirai, Yoshiharu Uchimoto, Jun Ichi Yamaki, Zempachi Ogumi, In situ Zn/ZnO mapping elucidating for "shape change" of zinc electrode, APL Materials, 10.1063/1.5011272, 6, 4, 2018.04, [URL], For the use of the zinc anode in secondary batteries, it is necessary to solve the "shape change" deterioration issue in that zinc species agglomerate in the center of the electrode to fade the available capacity. The local chemical compositions of the zinc electrodes during "shape change" were precisely analyzed using the synchrotron X-ray diffraction mapping analysis of practical zinc-nickel cells in a non-destructive manner. The in situ Zn/ZnO mapping shows that metallic Zn deposition chiefly occurs in the periphery of ZnO while ZnO are left in the center of electrode like a hill on charging. On discharging, the ZnO hill grows to the perpendicular direction on the electrode while metallic zinc is oxidized and dissolved. These findings allow us to propose a mechanism for the shape change; thus dissolved zincate species are decomposed on the ZnO hill during discharging to be accumulated in the center of the electrode. It is suggested that suppressing zincate dissolution and non-uniform zinc deposition slow the growth rate of the ZnO hill to enhance the cyclability of zinc-based secondary batteries..
7. Yukinori Koyama, Takeshi Uyama, Yuki Orikasa, Takahiro Naka, Hideyuki Komatsu, Keiji Shimoda, Haruno Murayama, Katsutoshi Fukuda, Hajime Arai, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi, Hidden Two-Step Phase Transition and Competing Reaction Pathways in LiFePO4, Chemistry of Materials, 10.1021/acs.chemmater.6b05000, 29, 7, 2855-2863, 2017.04, [URL], LiFePO4 is a well-known electrode material that is capable of high-rate charging and discharging despite a strong phase-separation tendency of the lithium-rich and poor end-member phases. X-ray diffraction measurements (XRD) with high time-resolution are conducted under battery operation conditions to reveal the phase-transition mechanism of LiFePO4 that leads to the high rate capability. We here propose a hidden two-step phase transition of LiFePO4 via a metastable phase. The existence of the metastable phase, not just a member of a transient solid solution, is evidenced by the operando XRD measurements. Our two-step phase-transition model explains the behavior of LiFePO4 under the battery operation conditions. It also explains asymmetric behavior during the charging and discharging at high rates and low temperatures, as well as apparent single-step two-phase reaction between the end members at low rates at room temperature. This model also suggests underlying, rate-dependent electrochemical processes that result from a competing disproportion reaction of the metastable phase..
8. Haruno Murayama, Takayuki Hasegawa, Yusuke Yamamoto, Misaki Tone, Moemi Kimura, Tamao Ishida, Tetsuo Honma, Mitsutaka Okumura, Atsuko Isogai, Tsutomu Fujii, Makoto Tokunaga, Chloride-free and water-soluble Au complex for preparation of supported small nanoparticles by impregnation method, Journal of Catalysis, 10.1016/j.jcat.2017.07.002, 353, 74-80, 2017.01, [URL], A novel simple and easy impregnation method for preparation of small gold (Au) nanoparticle (NP) catalysts (< 3 nm) deposited on various supports including silica, which is difficult to be applied for conventional methods, has been developed. Chloride-free and water-soluble precursor, Au complexes coordinated with β-alanine, were successful for the preparing Au NPs, which exhibited an average diameter less than 3 nm. Thermal behavior of the Au complex was investigated by TG-DTA and in situ XAFS. XAFS analyses and DFT calculations revealed a molecular structure of the Au complex to be square-planar coordination structure and mononuclear complex of Au3+. Lower decomposition and reduction temperature of the chloride-free Au complex prevented Au atoms from aggregating and from following growth of Au particles. The prepared Au/SiO2 showed high selectivity for hydrogenation of 1-nitro-4-vinylbenzene into 1-ethyl-4-nitorobenzene and good performance for removal of unpalatable aroma by means of adsorption of polysulfide molecules..
9. Zhenzhong Zhang, Yuhya Kumamoto, Taishin Hashiguchi, Tetsuya Mamba, Haruno Murayama, Eiji Yamamoto, Tamao Ishida, Tetsuo Honma, Makoto Tokunaga, Wacker Oxidation of Terminal Alkenes Over ZrO2-Supported Pd Nanoparticles Under Acid- and Cocatalyst-Free Conditions, ChemSusChem, 10.1002/cssc.201701016, 10, 17, 3482-3489, 2017, [URL], Highly efficient Wacker oxidation of aromatic or aliphatic terminal alkenes into methyl ketones and benzofurans is developed by using reusable Pd0 nanoparticles (NPs) supported on ZrO2 under acid- and cocatalyst-free conditions. Molecular oxygen or air can be utilized as the terminal oxidant, which results in the formation of H2O as the only theoretical byproduct. The activation of the Pd NPs by O2 plays an important role in promoting this reaction. Interestingly, PdO supported on ZrO2 showed no activity. Additionally, the Pd particle size significantly affects the catalytic activity, with an apparent optimal diameter of 4–12 nm. In addition to the heterogeneous catalyst forms, the Pd NPs can be generated from a Pd0 complex during the reaction, and these particles are even recyclable..
10. Zhenzhong Zhang, Qixun Wu, Taishin Hashiguchi, Tamao Ishida, Haruno Murayama, Makoto Tokunaga, Allylic C–H acetoxylation of terminal alkenes over TiO2 supported palladium nanoparticles using molecular oxygen as the oxidant, Catalysis Communications, 10.1016/j.catcom.2016.08.033, 87, 18-22, 2016.12, [URL], A method for synthesizing linear allylic acetates from terminal alkenes over TiO2 supported Pd nanoparticles (NPs) has been developed, in which O2 serves as the sole oxidant. Good catalytic activity was performed when using allylbenzene as a substrate and the catalyst can be reused at least five times without activity losing. The catalytic system has a broad substrate scope including transformation of 1,3-butadiene into 1,4-diacetoxy-2-butene, which is an important industrial intermediate for production of 1,4-butanediol. In contrast to previous reports that the Pd-catalyzed allylic acetoxylation is generally promoted by PdII species, the XAFS measurements suggest that this reaction is catalyzed over Pd0 NPs. Additionally, XPS analysis of the catalyst confirms the interaction between Pd and TiO2, which probably promote the initial catalytic procedure..
11. Tamao Ishida, Kurumi Kume, Kota Kinjo, Tetsuo Honma, Kengo Nakada, Hironori Ohashi, Takushi Yokoyama, Akiyuki Hamasaki, Haruno Murayama, Yusuke Izawa, Masaru Utsunomiya, Makoto Tokunaga, Efficient Decarbonylation of Furfural to Furan Catalyzed by Zirconia-Supported Palladium Clusters with Low Atomicity, ChemSusChem, 10.1002/cssc.201601232, 9, 24, 3441-3447, 2016.12, [URL], Decarbonylation of furfural to furan was efficiently catalyzed by ZrO2-supported Pd clusters in the liquid phase under a N2 atmosphere without additives. Although Pd/C and Pd/Al2O3 have frequently been used for decarbonylation, Pd/ZrO2 exhibited superior catalytic performance compared with these conventional catalysts. Transmission electron microscopy and X-ray absorption fine structure measurements revealed that the size of the Pd particles decreased with an increase in the specific surface area of ZrO2. ZrO2 with a high surface area immobilized Pd as clusters consisting of several (three to five) Pd atoms, whereas Pd aggregated to form nanoparticles on other supports such as carbon and Al2O3 despite their high surface areas. The catalytic activity of Pd/ZrO2 was enhanced with a decrease in particle size, and the smallest Pd/ZrO2 was the most active catalyst for decarbonylation. When CeO2 was used as the support, a decrease in Pd particle size with an increase in surface area was also observed. Single Pd atoms were deposited on CeO2 with a high surface area, with a strong interaction through the formation of a Pd−O−Ce bond, which led to a lower catalytic activity than that of Pd/ZrO2. This result suggests that zero-valent small Pd clusters consisting of more than one Pd atom are the active species for the decarbonylation reaction. Recycling tests proved that Pd/ZrO2 maintained its catalytic activity until its sixth use..
12. Ikuma Takahashi, Katsutoshi Fukuda, Tomoya Kawaguchi, Hideyuki Komatsu, Masatsugu Oishi, Haruno Murayama, Masaharu Hatano, Takayuki Terai, Hajime Arai, Yoshiharu Uchimoto, Eiichiro Matsubara, Quantitative Analysis of Transition-Metal Migration Induced Electrochemically in Lithium-Rich Layered Oxide Cathode and Its Contribution to Properties at High and Low Temperatures, Journal of Physical Chemistry C, 10.1021/acs.jpcc.6b08199, 120, 48, 27109-27116, 2016.12, [URL], Lithium-rich layered oxides (LLOs) have attracted much attention as high-capacity electrodes in lithium-ion batteries. Especially, LLOs are known to show high performance at high temperature. The transition metal (TM) migrates from the TM layer to the Li layer in the LLO active material during the charge-discharge cycle, which complicates our understanding of its electrochemical properties. In this study, we applied X-ray diffraction spectroscopy (XDS) for acquiring quantitative data on TM migration depending on the crystallographic site in Li1.2-xNi0.13Co0.13Mn0.53O2, and we discuss their influence on the electrochemical properties at 40 and -10°C. The XDS analysis shows that both Mn and Ni in the TM layer migrate to the Li layer during the charge process and return during the discharge process. This reversible migration, observed at 40°C, corresponds to a high capacity. On the other hand, the operation at -10°C decreases the degree of TM migration as well as the charge-discharge capacity. In particular, Mn and Ni hardly migrate to the TM layer and remain at the Li layer at the end of discharge. This clogged interlayer space, which would lower the Li+ diffusion, accounts for the capacity drop. (Graph Presented)..
13. Ikuma Takahashi, Takuya Mori, Takahiro Yoshinari, Yuki Orikasa, Yukinori Koyama, Haruno Murayama, Katsutoshi Fukuda, Masaharu Hatano, Hajime Arai, Yoshiharu Uchimoto, Takayuki Terai, Irreversible phase transition between LiFePO4 and FePO4 during high-rate charge-discharge reaction by operando X-ray diffraction, Journal of Power Sources, 10.1016/j.jpowsour.2016.01.077, 309, 122-126, 2016.03, [URL], LiFePO4 is a practically used cathode material for lithium-ion batteries due to a high theoretical capacity, high cycle capability and the high-rate performance. The metastable LixFePO4 (LxFP) phase with an intermediate composition appears in the non-equilibrium state at high-rate condition. However, the formation process of the metastable LxFP phase and its impact to the electrochemical property are still unclear. In order to elucidate these points, we directly observed the phase transition behavior by applying operando XRD during 10C charge-discharge. LxFP phase does not form in charge reaction but preferentially forms in discharge reaction. The phase transition from LxFP to Li-rich phase is less likely to proceed in the end of discharge reaction. The asymmetric phase transition between LiFePO4 and FePO4 results in decreasing the discharge capacity and increasing the irreversible capacity at high-rate conditions..
14. Koji Kitada, Haruno Murayama, Katsutoshi Fukuda, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Eiichiro Matsubara, Factors determining the packing-limitation of active materials in the composite electrode of lithium-ion batteries, Journal of Power Sources, 10.1016/j.jpowsour.2015.09.105, 301, 11-17, 2016.01, [URL].
15. Ikuma Takahashi, Hajime Arai, Haruno Murayama, Kenji Sato, Hideyuki Komatsu, Hajime Tanida, Yukinori Koyama, Yoshiharu Uchimoto, Zempachi Ogumi, Phase transition kinetics of LiNi0.5Mn1.5O4 analyzed by temperature-controlled operando X-ray absorption spectroscopy, Physical Chemistry Chemical Physics, 10.1039/c5cp05535k, 18, 3, 1897-1904, 2016.01, [URL], LiNi0.5Mn1.5O4 (LNMO) is a promising positive electrode material for lithium ion batteries because it shows a high potential of 4.7 V vs. Li/Li+. Its charge-discharge reaction includes two consecutive phase transitions between LiNi0.5Mn1.5O4 (Li1) 虠 Li0.5Ni0.5Mn1.5O4 (Li0.5) and Li0.5 虠 Ni0.5Mn1.5O4 (Li0) and the complex transition kinetics that governs the rate capability of LNMO can hardly be analyzed by simple electrochemical techniques. Herein, we apply temperature-controlled operando X-ray absorption spectroscopy to directly capture the reacting phases from -20 °C to 40 °C under potential step (chronoamperometric) conditions and evaluate the phase transition kinetics using the apparent first-order rate constants at various temperatures. The constant for the Li1 虠 Li0.5 transition (process 1) is larger than that for the Li0.5 虠 Li0 transition (process 2) at all the measured temperatures, and the corresponding activation energies are 29 and 46 kJ mol-1 for processes 1 and 2, respectively. The results obtained are discussed to elucidate the limiting factor in this system as well as in other electrode systems..
16. Akiyoshi Nakata, Haruno Murayama, Katsutoshi Fukuda, Tomokazu Yamane, Hajime Arai, Toshiro Hirai, Yoshiharu Uchimoto, Jun Ichi Yamaki, Zempachi Ogumi, Transformation of leaf-like zinc dendrite in oxidation and reduction cycle, Electrochimica Acta, 10.1016/j.electacta.2015.03.076, 166, 82-87, 2015.06, [URL], Abstract Zinc is a promising negative electrode material for aqueous battery systems whereas it shows insufficient rechargeability for use in secondary batteries. It has been reported that leaf-like dendrite deposits are often the origin of cell-failure, however, their nature and behavior on discharge (oxidation) - charge (reduction) cycling have been only poorly understood. Here we investigate the transformation of the leaf-like zinc dendrites using ex-situ scanning electron microscopy, X-ray computational tomography and in-situ X-ray diffraction. It is shown that the leaf-like zinc dendrites obtained under diffusion-limited conditions are nearly completely dissolved at a low oxidation current density of 1 mA cm-2 and cause re-evolution of the zinc dendrites. Oxidation at a high current density of 10 mA cm-2 leads to the formation of leaf-like zinc oxide residual products that result in particulate zinc deposits in the following reduction process, enabling good rechargeability. The reaction behavior of this oxide residue is detailed and discussed for the development of long-life zinc electrodes..
17. Akiyoshi Nakata, Katsutoshi Fukuda, Haruno Murayama, Hajime Tanida, Tomokazu Yamane, Hajime Arai, Yoshiharu Uchimoto, Kenji Sakurai, Zempachi Ogumi, Operando x-ray fluorescence imaging for zinc-based secondary batteries, Electrochemistry, 10.5796/electrochemistry.83.849, 83, 10, 849-851, 2015.01, [URL], Zinc-based secondary aqueous batteries are promising candidates as innovative batteries for their high energy density and high safety. Their limited cycle life is chiefly due to the morphology changes of the zinc electrode and thus tracking the zinc distribution during electrochemical processes is indispensable for clarifying the deterioration mechanism of the zinc electrode. We here report the zinc distribution near the electrode in a millimeter scale on zinc reduction and oxidation observed by operando X-ray fluorescence imaging with a high time resolution. The zinc dendritic growth and its dissolution behavior is discussed based on the obtained zinc distribution images..
18. Hideyuki Komatsu, Hajime Arai, Yukinori Koyama, Kenji Sato, Takeharu Kato, Ryuji Yoshida, Haruno Murayama, Ikuma Takahashi, Yuki Orikasa, Katsutoshi Fukuda, Tsukasa Hirayama, Yuichi Ikuhara, Yoshio Ukyo, Yoshiharu Uchimoto, Zempachi Ogumi, Solid Solution Domains at Phase Transition Front of LixNi0.5Mn1.5O4, Advanced Energy Materials, 10.1002/aenm.201500638, 5, 17, 2015.01, [URL], Nickel-substituted manganese spinel LiNi0.5Mn1.5O4 (LNMO) is a promising 5 V class positive electrode material for lithium-ion batteries. As micron-sized LNMO particles show high rate capability in its two-phase coexistence regions, the phase transition mechanism is of great interest in understanding the electrode behavior at high rates. Here, the phase transition dynamics of LixNi0.5Mn1.5O4 is elucidated on high rate charging-discharging using operando time-resolved X-ray diffraction (TR-XRD). The TR-XRD results indicate the existence of intermediate states, in addition to the thermodynamically stable phases, and it is shown that the origin of such intermediate states is ascribed to the solid-solution domains at the phase transition front, as supported by the analysis using transmission electron microscopy coupled with electron energy-loss spectroscopy. The phase transition pathways dependent on the reaction rate are shown, together with possible explanation for this unique transition behavior..
19. Hidetaka Sugaya, Katsutoshi Fukuda, Masahito Morita, Haruno Murayama, Eiichiro Matsubara, Toshirou Kume, Yoshiharu Uchimoto, High-capacity lithium-ion storage system using unilamellar crystallites of exfoliated MoO2 nanosheets, Chemistry Letters, 10.1246/cl.150706, 44, 11, 1595-1597, 2015, [URL], The electrochemical properties of a composite electrode for the lithium-ion battery consisting of exfoliated MoO2 nanosheets were investigated. The cell exhibited a high capacity of ca. 400 mA h g-1 in the cell voltage range of 3.0-0.1 V, even after several charge-discharge cycles. In situ X-ray analysis during the electrochemical test revealed that multiple injections of Li+ into the interlayers between the MoO2 nanosheets and subsequent delithiation from the material occurred reversibly at room temperature..
20. Ikuma Takahashi, Haruno Murayama, Kenji Sato, Takahiro Naka, Koji Kitada, Katsutoshi Fukuda, Yukinori Koyama, Hajime Arai, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi, Kinetically asymmetric charge and discharge behavior of LiNi 0.5Mn1.5O4 at low temperature observed by in situ X-ray diffraction, Journal of Materials Chemistry A, 10.1039/c4ta01130a, 2, 37, 15414-15419, 2014.10, [URL], Capacity decrease at low temperatures is one of the issues to be solved for secondary batteries especially for automobile applications and it is thus important to clarify the reaction kinetics in operating batteries and identify the rate determining step that governs the performance at low temperatures. Phase transitions in electrode active materials are important factors that affect the reaction kinetics particularly for thin electrodes used in high power applications. In this study, the phase transition dynamics of thin LiNi 0.5Mn1.5O4 electrodes at various temperatures is examined using electrochemical methods combined with temperature-controlled in situ X-ray diffraction analysis to directly capture the reacting species and elucidate the reaction mechanism. The analysis shows that there occur consecutive phase transitions of LiNi0.5Mn1.5O4 (Li1 phase) ↔ Li0.5Ni0.5Mn1.5O 4 (Li0.5 phase) and the Li0.5 phase ↔ Ni0.5Mn 1.5O4 (Li0 phase) at room temperature and above. At lower temperatures the transition of Li1 → Li0.5 proceeds during the charging process but further delithiation to form the Li0 phase is restricted, leading to the capacity decrease. On the other hand, on discharging at low temperatures the amount of the Li0 phase to be lithiated is limited and this causes the capacity decrease. There is no Li0.5 phase formation on discharging at low temperatures, revealing remarkable kinetic asymmetry of the reaction processes for charging and discharging. It is suggested that the Li0.5 phase formed on discharging is instantly lithiated to form the Li1 phase, due to the small potential gap between the two transitions. These results indicate that the phase transition kinetics of Li0.5 ↔ Li0 is slower than that of Li1 ↔ Li0.5 and the former transition is the rate determining step at low temperatures..
21. Haruno Murayama, Koji Kitada, Katsutoshi Fukuda, Akio Mitsui, Koji Ohara, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Eiichiro Matsubara, Spectroscopic X-ray diffraction for microfocus inspection of Li-ion batteries, Journal of Physical Chemistry C, 10.1021/jp5029273, 118, 36, 20750-20755, 2014.09, [URL].
22. Kentaro Yamamoto, Taketoshi Minato, Shinichiro Mori, Daiko Takamatsu, Yuki Orikasa, Hajime Tanida, Koji Nakanishi, Haruno Murayama, Titus Masese, Takuya Mori, Hajime Arai, Yukinori Koyama, Zempachi Ogumi, Yoshiharu Uchimoto, Improved cyclic performance of lithium-ion batteries
An investigation of cathode/electrolyte interface via in situ total-reflection fluorescence X-ray absorption spectroscopy, Journal of Physical Chemistry C, 10.1021/jp5011132, 118, 18, 9538-9543, 2014.05, [URL], For the further development of lithium-ion batteries, improvement of their cyclic performance is crucial. However, the mechanism underlying the deterioration of the battery cyclic performance is not fully understood. We investigated the effects of the electronic structure at the electrode/ electrolyte interface on the cyclic performance of the cathode materials via in situ total-reflection fluorescence X-ray absorption spectroscopy. In a LiCoO2 thin-film electrode that exhibits gradual deterioration upon subsequent Li ion extractions and insertions (cycling), the reduction of Co ions at the electrode/electrolyte interface was observed upon immersion in an organic electrolyte, with subsequent irreversible changes after cycling. In contrast, in a LiFePO4 thin-film electrode, the electronic structure at the electrode/electrolyte interface was stable and reversible upon electrolyte immersion with subsequent cycling. The increased stability of the electronic structure at the LiFePO4/electrolyte interface affects its cycling performance..
23. Hiroyuki Kawaura, Daiko Takamatsu, Shinichiro Mori, Yuki Orikasa, Hidetaka Sugaya, Haruno Murayama, Kouji Nakanishi, Hajime Tanida, Yukinori Koyama, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, High potential durability of LiNi0.5Mn1.5O 4 electrodes studied by surface sensitive X-ray absorption spectroscopy, Journal of Power Sources, 10.1016/j.jpowsour.2013.07.011, 245, 816-821, 2014.01, [URL], Phenomena at electrode/electrolyte interface of LiNi0.5Mn 1.5O4 are studied by in situ total-reflection fluorescence X-ray absorption spectroscopy (TRF-XAS), ex situ X-ray photoelectron spectroscopy (XPS), and electrochemical tests. Flat and well-defined thin films of LiNi0.5Mn1.5O4 prepared by pulsed laser deposition (PLD) are used as model electrodes to facilitate the observation of the interface. The thin-film LiNi0.5Mn1.5O4 electrode showed good cycling characteristics at around 4.7 V vs. Li/Li +. The TRF-XAS measurements reveal that nickel and manganese species at the surface have almost the same chemical states and local environments as those in the bulk when in contact with organic electrolyte solutions (1 mol dm-3 LiClO4 in a 1:1 volumetric mixture of ethylene carbonate and diethyl carbonate). This is in sharp contrast to the behavior of a LiCoO2 electrode, in which the surface cobalt species is irreversibly reduced by soaking to the organic electrolyte solutions, leading to gradual material deterioration during the delithiation/lithiation cycling (D. Takamatsu et al., Angew. Chem. Int. Edit., 51 (2012) 11597). It is suggested that the electrolyte decomposition products detected by XPS form a protective layer to restrict the reduction of the surface species of LiNi 0.5Mn1.5O4, leading to good cycling characteristics of LiNi0.5Mn1.5O4 in spite of its high operating potential..
24. Kaori Hibino, Takahiro Fujimoto, Koji Kitada, Katsutoshi Fukuda, Hajime Tanida, Koji Ohara, Haruno Murayama, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Output fading mechanism of mixed composite cathode in lithium ion battery, LLIBTA Symposium - Large Lithium Ion Battery Technology and Application, LLIBTA 2014
AABC Asia 2014 - Advanced Automotive Battery Confernce, LLIBTA Symposium - Large Lithium Ion Battery Technology and Application, LLIBTA 2014
, 2014.01.
25. H. Tanida, K. Fukuda, Haruno Murayama, Y. Orikasa, H. Arai, Y. Uchimoto, E. Matsubara, T. Uruga, K. Takeshita, S. Takahashi, M. Sano, H. Aoyagi, A. Watanabe, N. Nariyama, H. Ohashi, H. Yumoto, T. Koyama, Y. Senba, T. Takeuchi, Y. Furukawa, T. Ohata, T. Matsushita, Y. Ishizawa, T. Kudo, H. Kimura, H. Yamazaki, T. Tanaka, T. Bizen, T. Seike, S. Goto, H. Ohno, M. Takata, H. Kitamura, T. Ishikawa, T. Ohta, Z. Ogumi, RISING beamline (BL28XU) for rechargeable battery analysis, Journal of Synchrotron Radiation, 10.1107/S1600577513025733, 21, 1, 268-272, 2014.01, [URL], The newly installed BL28XU beamline at SPring-8 is dedicated to in situ structural and electronic analysis of rechargeable batteries. It supports the time range (1 ms to 100 s) and spatial range (1 μm to 1 mm) needed for battery analysis. Electrochemical apparatus for battery charging and discharging are available in experimental hutches and in a preparation room. Battery analysis can be carried out efficiently and effectively using X-ray diffraction, X-ray absorption fine-structure analysis and hard X-ray photoelectron spectroscopy. Here, the design and performance of the beamline are described, and preliminary results are presented..
26. Kaori Hibino, Takahiro Fujimoto, Koji Kitada, Katsutoshi Fukuda, Hajime Tanida, Koji Ohara, Haruno Murayama, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Output fading mechanism of mixed composite cathode in lithium ion battery, AABTAM Symposium - Advanced Automotive Battery Technology, Application and Market, AABTAM 2014
AABC Asia 2014 - Advanced Automotive Battery Confernce, AABTAM Symposium - Advanced Automotive Battery Technology, Application and Market, AABTAM 2014
, 21, 2014.
27. Hajime Arai, Kenji Sato, Yuki Orikasa, Haruno Murayama, Ikuma Takahashi, Yukinori Koyama, Yoshiharu Uchimoto, Zempachi Ogumi, Phase transition kinetics of LiNi0.5Mn1.5O 4 electrodes studied by in situ X-ray absorption near-edge structure and X-ray diffraction analysis, Journal of Materials Chemistry A, 10.1039/c3ta11637a, 1, 35, 10442-10449, 2013.09, [URL], In situ time-resolved X-ray absorption near-edge structure (XANES) and X-ray diffraction (XRD) measurements are applied to track the phase transition processes of LixNi0.5Mn1.5O4, which is one of the most promising positive electrode materials for lithium ion batteries with its high redox potential of 4.7 V vs. Li/Li+ and good rate capability. Thanks to the high time resolution brought by a strong synchrotron X-ray beam, the XANES and XRD measurements separately capture the three phases involved in nearly the same potential region, namely LiNi 0.5Mn1.5O4 (Li1), Li1/2Ni 0.5Mn1.5O4 (Li1/2) and Ni0.5Mn 1.5O4 (Li0), and the phase transition kinetics under fast charging-discharging conditions is elucidated. The detailed kinetic analysis shows that the phase transitions are apparently expressed by the first-order kinetics and that the transition between the Li1 and Li1/2 phases is faster than that between the Li1/2 and Li0 phases, which leads to kinetically asymmetric behavior of the LiNi0.5Mn1.5O4 electrode. The obtained rate constants can be used to characterize and optimize the rate capability of the electrode..
28. H. Tanida, H. Yamashige, Y. Orikasa, T. Fujimoto, M. Oishi, Haruno Murayama, H. Arai, M. Katayama, Y. Inada, T. Ohta, Y. Uchimoto, Z. Ogumi, In situ two-dimensional micro-imaging XAFS with CCD detector, Journal of Physics: Conference Series, 10.1088/1742-6596/430/1/012021, 430, 1, 2013.05, [URL], In situ two-dimensional (2D) micro-imaging X-ray absorption fine structure (XAFS) measurements were performed in transmission mode using a charge coupled device (CCD) detector, phosphor screen, and magnifying lens. This method makes it possible to display a 2D image with a spatial resolution of around 2 μm at each energy point in a XAFS spectrum. The method was applied to in situ transmission micro-imaging XAFS measurement with a quick scanning technique..
29. Yuki Orikasa, Takehiro Maeda, Yukinori Koyama, Haruno Murayama, Katsutoshi Fukuda, Hajime Tanida, Hajime Arai, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi, Direct observation of a metastable crystal phase of LixFePO 4 under electrochemical phase transition, Journal of the American Chemical Society, 10.1021/ja312527x, 135, 15, 5497-5500, 2013.04, [URL], The phase transition between LiFePO4 and FePO4 during nonequilibrium battery operation was tracked in real time using time-resolved X-ray diffraction. In conjunction with increasing current density, a metastable crystal phase appears in addition to the thermodynamically stable LiFePO 4 and FePO4 phases. The metastable phase gradually diminishes under open-circuit conditions following electrochemical cycling. We propose a phase transition path that passes through the metastable phase and posit the new phase's role in decreasing the nucleation energy, accounting for the excellent rate capability of LiFePO4. This study is the first to report the measurement of a metastable crystal phase during the electrochemical phase transition of LixFePO4..
30. Yuki Orikasa, Takehiro Maeda, Yukinori Koyama, Haruno Murayama, Katsutoshi Fukuda, Hajime Tanida, Hajime Arai, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi, Transient phase change in two phase reaction between LiFePO4 and FePO4 under battery operation, Chemistry of Materials, 10.1021/cm303411t, 25, 7, 1032-1039, 2013.04, [URL], Transient states of phase transition in LiFePO4/FePO4 for lithium ion battery positive electrodes are investigated by time-resolved measurements. To directly detect changes in electronic and crystal structures under battery operation, in situ time-resolved X-ray absorption and diffraction measurements are performed, respectively. The phase fraction change estimated by the iron valence change is similar to the electrochemically expected change. The transient change of lattice constant during two phase reaction is clearly observed by the time-resolved X-ray diffraction measurement. The nonequilibrium lithium extraction behavior deviates from the thermodynamic diagram of the two phase system, resulting in continuous phase transition during electrochemical reactions..
31. Masatsugu Oishi, Takahiro Fujimoto, Yu Takanashi, Yuki Orikasa, Atsushi Kawamura, Toshiaki Ina, Hisao Yamashige, Daiko Takamatsu, Kenji Sato, Haruno Murayama, Hajime Tanida, Hajime Arai, Hideshi Ishii, Chihiro Yogi, Iwao Watanabe, Toshiaki Ohta, Atsushi Mineshige, Yoshiharu Uchimoto, Zempachi Ogumi, 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, Journal of Power Sources, 10.1016/j.jpowsour.2012.08.023, 222, 45-51, 2013.01, [URL], The redox reaction of Li1.16Ni0.15Co0.19Mn0.50O2 positive electrode material during the charging and discharging processes was investigated by using spectroscopic methods, i.e. in situ hard X-ray absorption near edge structure (XANES) at transition metal K-edges and ex situ soft XANES at oxygen K- and transition metal L-edges. The spectral changes of constituent elements during the initial charging to 4.5 V vs. Li/Li+ are quite similar to those of conventional layer-structured positive materials, such as LiNi1/3Mn1/ 3Co1/3O2. Ni2+ and Co3+ ions are fully oxidized to Ni4+ and Co4+, while Mn4+ remains unchanged. Ligand oxygen ions also take part in charge compensation. In the process of charging to 4.8 V via the plateau voltage region, no significant spectral change appears except partial reduction of Ni and Co ions in spite of lithium extraction. By discharging to 2.0 V the spectra of each element return to those of the pristine material..
32. Masatsugu Oishi, Takahiro Fujimoto, Yu Takanashi, Yuki Orikasa, Atsushi Kawamura, Toshiaki Ina, Hisao Yamashige, Daiko Takamatsu, Kenji Sato, Haruno Murayama, Hajime Tanida, Hajime Arai, Hideshi Ishii, Chihiro Yogi, Iwao Watanabe, Toshiaki Ohta, Atsushi Mineshige, Yoshiharu Uchimoto, Zempachi Ogumi, Charge compensation mechanisms in Li1.16Ni0.15Co 0.19Mn0.50O2 positive electrode material for Li-ion batteries analyzed by a combination of hard and soft X-ray absorption near edge structure, Journal of Power Sources, 10.1016/jjpowsour.2012.08.023, 222, 45-51, 2013.01, [URL], The redox reaction of Li1.16Ni0.15Co 0.19Mn0.50O2 positive electrode material during the charging and discharging processes was investigated by using spectroscopic methods, i.e. in situ hard X-ray absorption near edge structure (XANES) at transition metal K-edges and ex situ soft XANES at oxygen K- and transition metal L-edges. The spectral changes of constituent elements during the initial charging to 4.5 V vs. Li/Li+ are quite similar to those of conventional layer-structured positive materials, such as LiNi 1/3Mn1/3Co1/3O2. Ni2+ and Co3+ ions are fully oxidized to Ni4+ and Co4+, while Mn4+ remains unchanged. Ligand oxygen ions also take part in charge compensation. In the process of charging to 4.8 V via the plateau voltage region, no significant spectral change appears except partial reduction of Ni and Co ions in spite of lithium extraction. By discharging to 2.0 V the spectra of each element return to those of the pristine material..
33. Yuki Orikasa, Takehiro Maeda, Yukinori Koyama, Taketoshi Minato, Haruno Murayama, Katsutoshi Fukuda, Hajime Tanida, Hajime Arai, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi, Phase transition analysis between LiFePO4 and FePO4 by in-situ time-resolved X-ray absorption and X-ray diffraction, Journal of the Electrochemical Society, 10.1149/2.012305jes, 160, 5, 2013, [URL], In-situ time-resolved X-ray absorption spectroscopy (XAS) andX-ray diffraction (XRD) are applied to investigate the phase transition mechanism between LiFePO4 and FePO4. Phase formation kinetics is discussed by using the phase fractions of LiFePO4 and FePO 4 directly obtained from the XRD measurement and the amount of the passed current synchronized by the XRD measurement with Kolmogorov-Johnson-Mehl- Avrami (KJMA) analysis. For both of the lithium extraction and insertion process, the KJMA analysis from the XRD and amount of the passed current data indicate that the phase formation of LiFePO4 and FePO4 proceeds via onedimensional phase boundary movement. For the lithium extraction process, the two phase coexistence of LiFePO4 and FePO4 is observed under the potential step conditions, and the KJMA plot based on the passed current data is relatively in good agreement with the one based on the XRD data. On the other hand, for the lithium insertion process, considerable peak boarding which implies intermediate state formation during the phase transition occurs, and the LiFePO4 phase formation is delayed compared with the amount of the passed current, especially in the case of small particle size. These results indicate that the phase transition behavior during lithium insertion is different from that of the typical two phase reaction..
34. Shiki Yagai, Mari Usui, Tomohiro Seki, Haruno Murayama, Yoshihiro Kikkawa, Shinobu Uemura, Takashi Karatsu, Akihide Kitamura, Atsushi Asano, Shu Seki, Supramolecularly engineered perylene bisimide assemblies exhibiting thermal transition from columnar to multilamellar structures, Journal of the American Chemical Society, 10.1021/ja302574b, 134, 18, 7983-7994, 2012.05, [URL], Perylene 3,4:9,10-tetracarboxylic acid bisimide (PBI) was functionalized with ditopic cyanuric acid to organize it into complex columnar architectures through the formation of hydrogen-bonded supermacrocycles (rosette) by complexing with ditopic melamines possessing solubilizing alkoxyphenyl substituents. The aggregation study in solution using UV-vis and NMR spectroscopies showed the formation of extended aggregates through hydrogen-bonding and π-π stacking interactions. The cylindrical fibrillar nanostructures were visualized by microscopic techniques (AFM, TEM), and the formation of lyotropic mesophase was confirmed by polarized optical microscopy and SEM. X-ray diffraction study revealed that a well-defined hexagonal columnar (Col h) structure was formed by solution-casting of fibrillar assemblies. All of these results are consistent with the formation of hydrogen-bonded PBI rosettes that spontaneously organize into the Col h structure. Upon heating the Col h structure in the bulk state, a structural transition to a highly ordered lamellar (Lam) structure was observed by variable-temperature X-ray diffraction, differential scanning calorimetry, and AFM studies. IR study showed that the rearrangement of the hydrogen-bonding motifs occurs during the structural transition. These results suggest that such a striking structural transition is aided by the reorganization in the lowest level of self-organization, i.e., the rearrangement of hydrogen-bonded motifs from rosette to linear tape. A remarkable increase in the transient photoconductivity was observed by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements upon converting the Col h structure to the Lam structure. Transient absorption spectroscopy revealed that electron transfer from electron-donating alkoxyphenyl groups of melamine components to electron-deficient PBI moieties takes place, resulting in a higher probability of charge carrier generation in the Lam structure compared to the Col h structure..
35. Yu Takanashi, Yuki Orikasa, Masato Mogi, Masatsugu Oishi, Haruno Murayama, Kenji Sato, Hisao Yamashige, Daiko Takamatsu, Takahiro Fujimoto, Hajime Tanida, Hajime Arai, Toshiaki Ohta, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi, Thickness estimation of interface films formed on Li1-xCoO 2 electrodes by hard X-ray photoelectron spectroscopy, Journal of Power Sources, 10.1016/j.jpowsour.2011.08.097, 196, 24, 10679-10685, 2011.12, [URL], Solid electrolyte interface (SEI) films formed on Li1-xCoO 2 electrodes were observed with hard X-ray photoelectron spectroscopy (HX-PES). This paper particularly focuses on film thickness estimation using HX-PES with theoretical calculation. The validity of the calculation was proven by experiments using model SEI films. The native film formed on a LiCoO 2 composite electrode was estimated to be LiF with its thickness of 5 nm. Formation of Co (II) species on top of LiCoO2 was also indicated. Storage of the electrode at 60 °C brought about considerable film growth (30-40 nm) with carbonate compounds formation. SEI film changes during charging of the LiCoO2 electrode were also examined. The main component in the film was deduced to be LiF or a kind of fluorite, with its thickness decreased during charging. The SEI formation mechanisms are also elucidated..
36. Hajime Tanida, Hisao Yamashige, Yuki Orikasa, Masatsugu Oishi, Yu Takanashi, Takahiro Fujimoto, Kenji Sato, Daiko Takamatsu, Haruno Murayama, Hajime Arai, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi, In situ two-dimensional imaging quick-scanning XAFS with pixel array detector, Journal of Synchrotron Radiation, 10.1107/S0909049511031232, 18, 6, 919-922, 2011.11, [URL], 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..
37. Daiko Takamatsu, Takayuki Nakatsutsumi, Shinichiro Mori, Yuki Orikasa, Masato Mogi, Hisao Yamashige, Kenji Sato, Takahiro Fujimoto, Yu Takanashi, Haruno Murayama, Masatsugu Oishi, Hajime Tanida, Tomoya Uruga, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Nanoscale observation of the electronic and local structures of LiCoO 2 thin film electrode by depth-resolved X-ray absorption spectroscopy, Journal of Physical Chemistry Letters, 10.1021/jz2011226, 2, 20, 2511-2514, 2011.10, [URL], The electronic and local structural changes during electrochemical delithiation processes occurring at the electrode/electrolyte interface of LiCoO2 thin film electrode prepared by pulsed laser deposition were clarified by using depth-resolved X-ray absorption spectroscopy technique. We successfully obtained detailed microstructural information around the Li 1-xCoO2 electrode surface with a depth resolution of ca. 3 nm using a spectro-electrochemical cell. Our results revealed a remarkable increase in the local distortions at the Li1-xCoO2 surface after charging, and the distortions extended to the bulk of Li 1-xCoO2. Such unprecedented local distortions might be attributable to the marked deterioration of the electrodes..
38. N. Nishida, A. Miyashita, N. Hashimoto, Haruno Murayama, H. Tanaka, Regenerative synthesis of copper nanoparticles by photoirradiation, European Physical Journal D, 10.1140/epjd/e2011-10515-8, 63, 2, 307-310, 2011.07, [URL], Copper nanoparticles have attracted much attention because of their low cost, and because their use can contribute toward the sustainability of metal resources. In this study, copper nanoparticles were synthesized by the photoirradiation of copper acetate solution at room temperature. The diameter and chemical composition of the obtained copper nanoparticles were analyzed using field-emission scanning electron microscope (FE-SEM) spectrophotometer and an X-ray photoelectron spectrometer. Well-dispersed copper nanoparticles with ~5 nm in diameter were observed in the solution. On the other hand, when the nanoparticle solution was exposed to fresh air, nanoparticles were not observed in the solution. Furthermore, the copper nanoparticles were recovered from a solution of decomposed nanoparticles by re-photoirradiation..
39. Tomohiro Seki, Atsushi Asano, Shu Seki, Yoshihiro Kikkawa, Haruno Murayama, Takashi Karatsu, Akihide Kitamura, Shiki Yagai, Rational construction of perylene bisimide columnar superstructures with a biased helical sense, Chemistry - A European Journal, 10.1002/chem.201003540, 17, 13, 3599-3608, 2011.03, [URL], Discotic supramolecular complexes bearing six perylene bisimide (PBI) chromophores were prepared by mixing monotopically triple-hydrogen-bonding melamines equipped with two PBI chromophores and two 3,7-dimethyloctyl chiral handles with tritopically triple-hydrogen-bonding cyanuric acid (CA). UV/Vis and fluorescence titration experiments demonstrated that the discotic complexes were formed in methylcyclohexane by the 3:1 complexation between the melamines and CA. TEM and AFM studies revealed that the complexes hierarchically organize into fibrous columnar assemblies, which eventually results in the formation of organogels. Circular dichroism (CD) and flash-photolysis time resolved microwave conductivity measurements revealed the presence of extended chiral stacks of PBI chromophores within the columns. The anisotropy factors of the columnar assemblies are remarkably high (g=1.5× 10-3) when considering the presence of only one 3,7-dimethyloctyl chiral handle per perylene chromophore, suggesting that the columnar structures have a biased helical sense. The fact that the chiral centers are located inside the discotic complexes rather than at their peripheries might be unique structural property responsible for the rather strong optical activities for the assemblies of this chromophore. The effective transcription of the molecular chirality to the extended columnar assemblies through the formation of unique discotic complexes enables the expression of "majority-rules" chiral amplification effect, which is unprecedented for the supramolecular assemblies of PBIs..
40. Naomi Hashimoto, Naoki Nishida, Haruno Murayama, Hideki Tanaka, Stable transport of gas-born ag nanoparticles into liquid phase mediated by poly(vinylpyrrolidone) molecules, Chemistry Letters, 10.1246/cl.2011.144, 40, 2, 144-146, 2011, [URL], We demonstrate that gas-born nanoparticles can be transported into solution successfully. Our results show that Ag nanoparticles produced in gas phase are introduced into poly(vinylpyrrolidone) solution without structural changes such as nanoparticle aggregation. It is also shown that Ag nanoparticles in solution show surface plasmon resonance, suggesting that the optical properties of nanoparticles are not impaired by the transport from gas to liquid..
41. Shiki Yagai, Tomohiro Seki, Haruno Murayama, Yusuke Wakikawa, Tadaaki Ikoma, Yoshihiro Kikkawa, Takashi Karatsu, Akihide Kitamura, Yoshihito Honsho, Shu Seki, Structural and electronic properties of extremely long perylene bisimide nanofibers formed through a stoichiometrically mismatched, hydrogen-bonded complexation, Small, 10.1002/smll.201001344, 6, 23, 2731-2740, 2010.12, [URL], Extremely long nanofibers, whose lengths reach the millimeter regime, are generated via co-aggregation of a melamine-appended perylene bisimide semiconductor and a substituted cyanurate, both of which are ditopic triple-hydrogen-bonding building blocks; they co-aggregate in an unexpected stoichiometrically mismatched 1:2 ratio. Various microscopic and X-ray diffraction studies suggest that hydrogen-bonded polymeric chains are formed along the long axis of the nanofibers by the 1:2 complexation of the two components, which further stack along the short axis of the nanofibers. The photocarrier generation mechanism in the nanofibers is investigated by time-of-flight (TOF) experiments under electric and magnetic fields, revealing the birth and efficient recombination of singlet geminate electron-hole pairs. Flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements revealed intrinsic 1D electron mobilities up to 0.6 cm2 V -1 s-1 within nanofibers. Extremely long nanofibers, whose lengths reach the millimeter regime, are generated via co-aggregation of a melamine-appended perylene bisimide semiconductor and a substituted cyanurate, both of which are ditopic triple-hydrogen-bonding building blocks. Microscopy and X-ray diffraction studies suggest that hydrogen-bonded polymeric chains are formed along the long axis of the nanofibers by the 1:2 complexation of the two components, which further stack along the short axis of the nanofibers..
42. Yoshimitsu Fukuyama, Nobuhiro Yasuda, Shigeru Kimura, Yoshihito Tanaka, Hitoshi Osawa, Jungeun Kim, Haruno Murayama, Yutaka Moritomo, Koshiro Toriumi, Hitoshi Tanaka, Masaki Takata, Pump-probe x-ray diffraction technique for irreversible phase change materials, 10th International Conference on Synchrotron Radiation Instrumentation, SRI 2009
SRI 2009 - The 10th International Conference on Synchrotron Radiation Instrumentation
, 10.1063/1.3463176, 1234, 215-218, 2010.08, [URL], We have developed a pump-probe X-ray diffraction measurement system for a sample with irreversible reaction at BL40XU in the SPring-8. The system mainly consists of a time-resolved measurement system, a sample disk rotation system, and an X-ray microbeam system. The time-resolved measurement system gives time resolution of 50 ps in laser-pump and X-ray probe method. A sample disk rotation system for repetitive measurements was made to give a virgin sample for every measurement. The number of repetitions for one sample disk was increased by using the X-ray microbeam technique. To keep the overlap of the X-ray microbeam and the laser beam on the sample surface during the disk rotation, the sample disk rotation system was constructed by a low-eccentric spindle motor. By using this system, the pump-probe X-ray diffraction measurement was demonstrated for a crystallization process of a DVD material..
43. Yoshimitsu Fukuyama, Nobuhiro Yasuda, Hayato Kamioka, Jungeun Kim, Takayuki Shibata, Hitoshi Osawa, Takeshi Nakagawa, Haruno Murayama, Kenichi Kato, Yoshihito Tanaka, Shigeru Kimura, Takashi Ohshima, Hitoshi Tanaka, Masaki Takata, Yutaka Moritomo, Simultaneous measurements of picosecond lattice and charge dynamics in Co-Fe cyanides, Applied Physics Express, 10.1143/APEX.3.016601, 3, 1, 2010.01, [URL], Simultaneous measurements of picosecond time-resolved synchrotron-radiation (SR) X-ray diffraction and femtosecond time-resolved visible absorption were performed at BL40XU beamline of SPring-8 on two films of Co-Fe cyanides, Na 0:77Co[Fe(CN)6]0:902.9H2O (NCF90) and Na0:16Co[Fe(CN)6]0:713.8H2O (NCF71). The simultaneous measurements unambiguously revealed that the photoinduced charge transfer between the Co and Fe sites causes uniform volume expansion/contraction within 100 ps. The photoinduced lattice contraction observed in the NCF71 film can be interpreted in terms of the photoinduced formation of a hidden metastable phase..
44. Haruno Murayama, Naomi Hashimoto, Hideki Tanaka, Ag triangular nanoplates synthesized by photo-induced reduction
Structure analysis and stability, Chemical Physics Letters, 10.1016/j.cplett.2009.10.015, 482, 4-6, 291-295, 2009.12, [URL], Ag triangular nanoplates were synthesized by photoirradiation to AgNO3 ethanol solution in the presence of polyvinylpyrrolidone (PVP) under anaerobic conditions at room temperature. High-resolution SEM and TEM observations revealed that thin Ag equilateral triangular nanoplates, each of which was a single crystal with sharp corners and flat faces presented by {1 1 1} planes, were produced. Analyses of XAFS and XPS have shown that these nanoplates are protected by coordination of O atoms in PVP molecules, not being oxidized as Ag2O. The nanoplates are inherently stable, though they were easily truncated and dissolved if mixed with oxygen or water..
45. M. Takata, Y. Tanaka, K. Kato, F. Yoshida, Y. Fukuyama, N. Yasuda, S. Kohara, H. Osawa, T. Nakagawa, J. Kim, Haruno Murayama, S. Kimura, H. Kamioka, Y. Moritomo, T. Matsunaga, R. Kojima, N. Yamada, T. Ohshima, H. Tanaka, Structure and the mechanism of rapid phase change in amorphous Ge 2Sb2Te2, Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B, 50, 3, 205-211, 2009.06, Understanding the mechanism of rapid phase change process in DVD (digital versatile disc) materials is one of the important topics in materials science, and hence numerous studies investigating the phase change process as well as structural analysis of the crystal and amorphous phases have been reported. Nevertheless, the mechanism of rapid phase change is still unclear, owing to the lack of detailed structure analysis, in particular on the amorphous phase and its crystallisation process. We have studied the amorphous structure of Ge 2Sb2Te5 and the crystallisation process by high energy synchrotron x-ray diffraction with the aid of structure modelling and time-resolved synchrotron x-ray diffraction, in order to obtain key information for revealing the rapid phase change mechanism. We found a large fraction of 4-fold and 6-fold rings in the atomic configuration of the amorphous phase. Intriguingly the bond angle distributions of rings exhibit a peak at approximately 90°, which corresponds to that in the crystal phase. Therefore, it is suggested that the 4-fold and 6-fold rings are nuclei for crystallisation. Furthermore, time-resolved x-ray diffraction measurements combined with photoreflectivity measurements during the crystallisation of the amorphous phase suggest that the crystallisation of Ge2Sb 2Te5 can be explained by a nucleation driven process. We conclude that a large amount of nuclei is the reason for rapid crystallisation in Ge2Sb2Te5 with a nucleation driven process..
46. Yoshihito Tanaka, Yoshimitsu Fukuyama, Nobuhiro Yasuda, Jungeun Kim, Haruno Murayama, Shinji Kohara, Hitoshi Osawa, Takeshi Nakagawa, Shigeru Kimura, Kenich Kato, Fumiko Yoshida, Hayato Kamioka, Yutaka Moritomo, Toshiyuki Matsunaga, Rie Kojima, Noboru Yamada, Koshiro Toriumi, Takashi Ohshima, Hitoshi Tanaka, Masaki Takata, Development of picosecond time-resolved microbeam X-ray diffraction technique for investigation of optical recording process, Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes, 10.1143/JJAP.48.03A001, 48, 3 PART 2, 2009.03, [URL], A time-resolved structural investigation of the data storage process in a digital versatile disk (DVD) or Blu-ray disk media is desired for better understanding of the fast phase-change mechanism for designing a higher performance optical recording material. Thus, the development of an in situ structural observation technique at the picosecond level has been carried out for the investigation of the fast phase-change phenomena using synchrotron radiation pulsed X-rays and synchronized femtosecond laser irradiation. Then, for Ge2Sb2Te5 (GST) and Ag3:5In3:8Sb75:0Te17:7 (AIST), the technique has been applied to a snapshot of X-ray diffraction pattern in the nanosecond crystallization process from the amorphous to the crystal phase, which corresponds to the erasing process of the DVD recording system. The key to success of the time-resolved experiment was to optimize the measurement timing system efficiency for both sufficient counting statistics, i.e., counting quantity and precision of time resolution, i.e., counting quality. Our time-resolved experimental system has sufficient accuracy, so that our previous study showed a significant difference in the crystal growth process between GST and AIST, indicating that the crystal growth process is key to fast phase change. To increase the precision of data in terms of signal-to-noise ratio and counting statistics, we developed a highly repetitive pump-probe measurement system combined with an X-ray microbeam technique providing high counting quantity, and used it to demonstrate a snapshot of an X-ray diffraction profile of GST. The measurement system has a time resolution of 50 ps and a 1 kHz repetition rate. Our development of the technique to take a snapshot for the structural visualization of phase-change phenomena with the time-resolved microbeam X-ray diffraction is described..
47. Haruno Murayama, N. Hashimoto, H. Tanaka, Growth process of Ag triangular nanoplates observed by in situ XAFS, Journal of Physics: Conference Series, 10.1088/1742-6596/190/1/012132, 190, 2009, [URL], We examined to establish the simple synthesis method of Ag triangular nanoplates in order to elucidate their growth process. Ethanol solution of AgNO3 was photoirradiated without reduction agents except in the presence of PVP, poly(vinil-pyrrolidone). Electron microscope observations revealed that the shape of the product was Ag triangular nanoplates with sharp corners and a flat face. In situ XAFS and optical absorption measurements suggested that the Ag triangular nanoplates were photoinduced-converted from Ag spherical nanoparticles via Ag truncated triangular nanoplates..
48. Nobuhiro Yasuda, Haruno Murayama, Yoshimitsu Fukuyama, Jungeun Kim, Shigeru Kimura, Koshiro Toriumi, Yoshihito Tanaka, Yutaka Moritomo, Yoshihiro Kuroiwa, Kenichi Kato, Hitoshi Tanaka, Masaki Takata, X-ray diffractometry for the structure determination of a submicrometre single powder grain, Journal of Synchrotron Radiation, 10.1107/S090904950900675X, 16, 3, 352-357, 2009, [URL], A high-precision diffractometer has been developed for the structure analysis of a submicrometre-scale single grain of a powder sample at the SPring-8 BL40XU undulator beamline. The key design concept is the combination of a stable focused synchrotron radiation beam and the precise axis control of the diffractometer, which allows accurate diffraction intensity data of a submicrometre-scale single powder grain to be measured. The phase zone plate was designed to create a high-flux focused synchrotron radiation beam. A low-eccentric goniometer and high-precision sample positioning stages were adopted to ensure the alignment of a micrometre-scale focused synchrotron radiation beam onto the submicrometre-scale single powder grain. In order to verify the diffractometer performance, the diffraction pattern data of several powder grains of BaTiO3, of dimensions ̃600 × 600 × 300 nm, were measured. By identifying the diffraction data set of one single powder grain, the crystal structure was successfully determined with a reliable factor of 5.24%..
49. Masaharu Shigeyasu, Haruno Murayama, Hideki Tanaka, Production of nanoparticles composed of ionic liquid [C4mpyrr][NTf2] and their chemical identification by diameter analysis and X-ray photoelectron spectroscopy, Chemical Physics Letters, 10.1016/j.cplett.2008.08.068, 463, 4-6, 373-377, 2008.10, [URL], Production of nanoparticles composed of ionic liquid [C4mpyrr][NTf2], N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, was demonstrated by a gas aggregation technique under low pressure. The diameter spectra were measured by a differential mobility analyzer (DMA) and were dependent on the heating temperature. Photoelectron spectra for the nanoparticles diameter-selected at 10 nm were also measured by X-ray photoelectron spectroscopy (XPS), and their chemical composition and structure were identified by comparison with photoelectron spectra for neat ionic liquid. The form and surface structure of the nanoparticles deposited onto an Au-coated Si substrate were also determined..
50. Naomi Hashimoto, Haruno Murayama, Hideki Tanaka, Production of small Ag-containing Q60 nanoparticles under atmospheric condition, Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes, 10.1143/JJAP.47.4777, 47, 6 PART 1, 4777-4779, 2008.06, [URL], Ag-containing C60 nanoparticles were produced from Ag vapor interacting with C60 nanoparticles formed by C60 vapor. The particle diameter of the produced nanoparticles was measured using a differential mobility analyzer (DMA). The particle diameter dependence on the Ag vapor temperature was also measured using the DMA. The chemical composition of the produced nanoparticles was investigated by X-ray photoelectron spectroscopy. The experimental results indicated that the C60 nanoparticles worked prominently as a supporting nanomaterial for the Ag nanoparticles..
51. Yoshimitsu Fukuyama, Nobuhiro Yasuda, Jungeun Kim, Haruno Murayama, Yoshihito Tanaka, Shigeru Kimura, Kenichi Kato, Shinji Kohara, Yutaka Moritomo, Toshiyuki Matsunaga, Rie Kojima, Noboru Yamada, Hitoshi Tanaka, Takashi Ohshima, Masaki Takata, Time-resolved investigation of nanosecond crystal growth in rapid-phase-change materials
Correlation with the recording speed of digital versatile disc media, Applied Physics Express, 10.1143/APEX.1.045001, 1, 4, 450011-450013, 2008.04, [URL], The crystallization process in digital versatile disc (DVD) media was investigated using a time-resolved X-ray diffraction apparatus coupled with in situ photoreflectivity measurement. The time profiles of crystallization were found to be consistent with the changes in photoreflectivity. The phase changes were characterized by the start and end time; 90 ±1 and 273 ± 1 ns for Ge2Sb2Te5, and 85 ± 1 and 206 ± 1 ns for Ag3.5In3.5Sb75.0Te 17.7, respectively. The faster crystallization time in Ag 3.5In3.8Sb75.0Te17.7 is ascribed to its characteristic crystallization process; its X-ray diffraction profile shows a significant sharpening during the crystallization process, whereas the peak width of Ge2Sb2Te5 remained unchanged. The present findings suggest that crystal growth control is another key for designing faster phasechange materials..
52. Yoshimitsu Fukuyama, Nobuhiro Yasuda, Jungeun Kim, Haruno Murayama, Takashi Ohshima, Yoshihito Tanaka, Shigeru Kimura, Hayato Kamioka, Yutaka Moritomo, Koshiro Toriumi, Hitoshi Tanaka, Kenichi Kato, Tetsuya Ishikawa, Masaki Takata, Ultra-high-precision time control system over any long time delay for laser pump and synchrotron x-ray probe experiment, Review of Scientific Instruments, 10.1063/1.2906232, 79, 4, 2008, [URL], An ultra-high-precision clock system for long time delay has been developed for picosecond time-resolved x-ray diffraction measurements using synchrotron radiation (SR) pulses and synchronized femtosecond laser pulses. The time delay control between pump laser pulse and the probe SR pulse was achieved by combining an in-phase quadrature modulator and a synchronous counter. This method allowed us to change the delay time by a nearly infinite amount while maintaining the precision of ±8.40 ps. Time-resolved diffraction measurements using the delay control system were demonstrated for precise measurement of an acoustic velocity in a single crystal of gallium arsenide..

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