新型電池の開発(全固体電池 等)
キーワード：ナトリウム、固体電解質、酸化物系全固体電池、空気電池、ナノポーラス電極
2014.04～2022.03.

複合アニオン化合物の創製と新機能
キーワード：酸水素化物, 炭窒化物, 材料プロセス, 解析
2016.08～2021.03.

元素戦略電子材料
キーワード：透明伝導体、ナノポーラス、元素戦略、電極、電池
2013.10～2017.03.

新学術領域「新学術領域「複合アニオン化合物の創製と新機能」
2016.08～2021.03, 代表者：陰山　洋, 京都大学, 京都大学
A02「複合アニオン化合物の理解：化学・構造・電子状態解析」複合アニオン化合物は、近年、急速発展している物質群であり、固体化学とその応用分野の革新と「元素戦略」の基軸となるポテンシャルを有しています。しかし、この物質群に対しては、酸化物等を対象とした従来の研究手法が通用せず、その結晶構造を決定するための評価・解析手法すら確立していない状態です。例えば、酸フッ化物(O2－-F－)系の複合アニオン化合物ではX 線回折・中性子回折いずれにおいても散乱断面積が近接するため、回折法でアニオン配置が決定できません。また、酸化物中に水素化物イオンH－が安定に存在するという事実は、結晶回折法、固体核磁気共鳴法および理論計算を駆使した研究成果を受けて、最近ようやく常識として認知されるようになりました。
新物質合成の折には、その「構造」が分からなければ先に進めません。物質機能は、その「状態」が分からなければ、機能発現の起源が分かりません。そこで、本研究班では、複合アニオン化合物の新物質探索と機能開拓の鍵となる、複合アニオン系に固有の構造情報を明らかにし、物質機能の理解と予測に繋げることを目的としています。複合アニオン系に展開することで直面する物質評価の問題をテーラーメードで解決し、手法の汎用化を図り、物質探索の加速を狙います。原子分解能の分析電子顕微鏡法、単結晶回折法と粉末回折法の最新計測法と向度解析に関する第一人者を取りそろえ、迅速な結晶構造決定と、酸素とフッ素の判別問題、混合水素化物、異常原子価のアニオンの検出等に取り組む。放射光X線吸収法、電子エネルギー損失分光法や固体核磁気共鳴法、吸着法、質量分析法等に深い経験を有する研究者が結集し、低次元物質、表面吸着、脱離など動的現象や低結晶性の物質や触媒表面の元素の状態分析に取り組みます。理論計算による襄付けや系統化の手段を取り入れます。また、理論計算の専門家を中心としてA01、03班と本班で蓄積された電気的・磁気的・化学的実験データと理論計算を融合し物性予測を行います。特に、電子状態・熱力学変数・機械特性に加えて、誘電性や熱電性等の格子振動を取り扱う計算負荷の高い解析手法にも対応できる体制を整え、研究項目A03と協同して新奇物性と機能性を発掘します。方法論の汎用化を図り、研究項目A01で創出される新物質の評価を効率化させます。.

元素戦略プロジェクト拠点形成型
2013.10～2019.03, 代表者：細野　秀雄, 東京工業大学, 文部科学省.

セラミックス分離型金属-空気電池へのセラミックス・金属材料学アプローチ
2014.04～2017.03, 代表者：林　克郎, 九州大学.

主要著書

主要原著論文

1.	Hiroshi Kageyama, Katsuro Hayashi, Kazuhiko Maeda, J. Paul Attfield, Zenji Hiroi, James M. Rondinelli, Kenneth R. Poeppelmeier, Expanding frontiers in materials chemistry and physics with multiple anions, Nature Communications, 9, Article No. 772, 2018.02.
2.	Katsuro Hayashi, Peter V. Sushko, Yasuhiro Hashimoto, Alexander L. Shluger, Hideo Hosono, Hydride Ions in Oxide Hosts Hidden by Hydroxide Ions, Nature Communications, 6, Article No. 4515, 2014.03, The true oxidation state of formally 'H(-)' ions incorporated in an oxide host is frequently discussed in connection with chemical shifts of (1)H nuclear magnetic resonance spectroscopy, as they can exhibit values typically attributed to H(+). Here we systematically investigate the link between geometrical structure and chemical shift of H(-) ions in an oxide host, mayenite, with a combination of experimental and ab initio approaches, in an attempt to resolve this issue. We demonstrate that the electron density near the hydrogen nucleus in an OH(-) ion (formally H(+) state) exceeds that in an H(-) ion. This behaviour is the opposite to that expected from formal valences. We deduce a relationship between the chemical shift of H(-) and the distance from the H(-) ion to the coordinating electropositive cation. This relationship is pivotal for resolving H(-) species that are masked by various states of H(+) ions.
3.	Katsuro Hayashi, Kazunari Shima, Fumiaki Sugiyama, A mixed aqueous/aprotic sodium/air cell using a NASICON ceramic separator, Journal of the Electrochemical Society, 10.1149/2.067309jes, 160, 9, 2013.07, [URL], An aqueous (mixed aqueous/aprotic) Na-air cell is fabricated and its discharge properties are examined experimentally. This design is attractive because Na is not only more abundant and cheaper than Li, but also potentially advantageous for enhancing cell output. The theoretical energy density of the aqueous Na-air cell exceeds that of a Li one under conditions where precipitation of hydroxides in the aqueous electrolyte is not allowed. Na 3Zr2Si2PO12 (NASICON) ceramics, which has a Na+ ion conductivity of 2 × 10-3 S · cm-1 at 50°C, is used as a solid electrolyte separator in the Na-air cell. Involvement of O2 gas in the cell reaction is verified by changing cell voltage in the presence or absence of O2 flow through the aqueous electrolyte. The Na-air cell exhibits an electrochemical discharge of ∼600 mAh· g-1 and energy density of ∼1500 Wh· kg-1 based on the weights of reacted Na and H2O. Its maximum areal output power is 11 mW· cm -2 and depends on the thickness of the NASICON ceramic separator, the concentration of NaOH in the aqueous electrolyte and the type of cathode, suggesting that cell performance can be improved by optimization of these components..
4.	Katsuro Hayashi, Peter V. Sushko, David Muñoz Ramo, Alexander L. Shluger, Satoshi Watauchi, Isao Tanaka, Satoru Matsuishi, Masahiro Hirano, Hideo Hosono, Nanoporous crystal 12CaO·Al2O3 A playground for studies of ultraviolet optical absorption of negative ions, Journal of Physical Chemistry B Materials, 10.1021/jp065793b, 111, 8, 1946-1956, 2007.03, [URL], A novel nanoporous material 12CaO·Al2O3 (C12A7) offers a possibility of incorporating large concentrations (>10 21 cm-3) of a wide range of extraframework anions inside its nanopores. We have investigated, both experimentally and theoretically, optical absorption associated with several types of such anions, including F-, OH-, O-, O2-, O2 2-, and O2 2-, and assigned their optical absorption bands. It is demonstrated that the chemical identity and concentration of extraframework anions can be controlled by an appropriate treatment of "as grown" C12A7. We also show that the position of the adsorption edge is, in turn, determined by the chemical identity of the extraframework species and can be varied in the range of ∼4-6 eV. We suggest that C12A7 is a unique host material, which can be used as a playground for studying negatively charged species that are unstable in other environments..
5.	Katsuro Hayashi, Peter V. Sushko, Alexander L. Shluger, Masahiro Hirano, Hideo Hosono, Hydride ion as a two-electron donor in a nanoporous crystalline semiconductor 12CaO·7Al2O3, Journal of Physical Chemistry B Materials, 10.1021/jp053990p, 109, 50, 23836-23842, 2005.12, [URL], The 12CaO·7Al203 (C12A7) crystal with a nanoporous lattice framework exhibits high electrical conductivity with an activation energy of ∼ 1.5 eV when equilibrated in a hydrogen atmosphere above ∼800°C. The high conductivity is preserved in a quenched state below ∼600°C with a reduced activation energy of ∼0.8 eV, Such complex behavior in electrical conductivity is associated with incorporation of hydride ions (H-) in cages of the lattice framework. Electromotive force measurements reveal that the major carrier for the conductivity is electron with a small contribution by proton (H+), ruling out the possibility of direct intercage migration of the H- ion. A combination of these observations with the ab initio calculations leads to the conclusion that the electrons are thermally generated from the H- ion by the dissociation into two electrons and an proton, which is further converted to an OH- ion via reaction with an extraframework oxide ion (02-). The energy difference between the initial (H- + O2-) and the final (2e- + OH-) states as evaluated by the theoretical calculation is as small as ∼1 eV, which agrees well with an experimentally obtained enthalpy change, ∼1.4 eV. Thus, internal equilibration between the extraframework hydrogen and the oxygen species is responsible for the thermal generation of the carrier electron. It is also suggested that the same conductive (2e- + OH-) state is reached by the photoirradiation of H--containing C12A7. In this case the photoionization of H- forms an electron and an H o atom, which then forms an OH- ion and another electron with thermal assistance. The persistence of photoinduced conductivity is explained by the slow kinetics of the reverse process at room temperature..
6.	Katsuro Hayashi, Masahiro Hirano, Hideo Hosono, Thermodynamics and kinetics of hydroxide ion formation in 12CaO·7Al 4O 3, Journal of Physical Chemistry B Materials, 10.1021/jp050807j, 109, 24, 11900-11906, 2005.06, [URL], We have examined the thermodynamics and kinetics of hydroxide (OH) ions that formed in cages of 12CaO·7Al 2O 3 (C12A7) with nanoporous structures. It is confirmed using thermogravimetric-evolved gas analyses (TG-EGA) that hydration in C12A7 is mediated by a reaction between an oxide (O 2-) ion in the cage and an H 2O molecule in the atmosphere to form two OH - ions in the cages. To simply and exactly quantify the OH - content from infrared absorption measurements of OH-stretching band, we propose a method combined with a thermodynamic analysis, allowing the simultaneous determination of the molar extinction coefficient of the OH-band, enthalpy, and entropy for the hydration. Hydration enthalpy in C12A7 is extremely high compared with other oxides and was enhanced by the marked instability of O 2- ion in the cage. Consequently, high solubility of OH - ion is retained up to unusually high temperatures. Furthermore, we determined diffusion coefficients of species relevant to the hydration process and demonstrated that inward diffusion of OH - ions is the rate-determining process..
7.	Satoru Matsuishi, Yoshitake Toda, Masashi Miyakawa, Katsuro Hayashi, Toshio Kamiya, Masahiro Hirano, Isao Tanaka, Hideo Hosono, High-density electron anions in a nanoporous single crystal [Ca24Al28O64]4+ (4e-), Science, 10.1126/science.1083842, 301, 5633, 626-629, 2003.08, [URL], We removed ∼100% of clathrated oxygen ions from the crystallographic cages in a single crystal of 12CaO·7Al2O3, leading to the formation of high-density (∼2 x 1021 cm-3) electrons highly localized in the cages. The resulting electron forms a structure that we interpret as an F+ center and migrates throughout the crystal by hopping to a neighboring cage with conductivity ∼100 siemens per centimeter, demonstrating that the encaged electron behaves as an anion. The electron anions couple antiferromagnetically with each other, forming a diamagnetic pair or singlet bipolaron. The resulting [Ca24Al28O64]4+(4e-) may be regarded as a thermally and chemically stable single crystalline "electride"..
8.	Katsuro Hayashi, Satoru Matsuishi, Naoto Ueda, Masahiro Hirano, Hideo Hosono, Maximum incorporation of oxygen radicals, O- and O2 -, into 12CaO·7Al2O3 with a nanoporous structure, Chemistry of Materials, 10.1021/cm020959g, 15, 9, 1851-1854, 2003.05, [URL], The effects of oxygen partial pressure (pO2) up to 400 atm on the generation of active oxygen radicals in 12CaO·7Al2O3 (C12A7) was examined using a hot isostatic pressing technique. Concentrations of superoxide (O2 -) and oxygen anion radicals (O-), which were analyzed from a combination of electron paramagnetic spin resonance (EPR) and Raman spectroscopy, increased with pO2. The total concentration of the radicals reached 1.7 × 1021 cm3, which is comparable to the theoretical maximum, confirmed that dominant radical incorporation process is O2- (cage) + O2 (atmosphere) → O- (cage) + O2 - (cage). The radical incorporated C12A7 has a large magnetic susceptibility that obeys Curie's law down to 2.5 K without magnetic ordering, although a weak exchange interaction was suggested by the line narrowing of the EPR signal..
9.	Katsuro Hayashi, Satoru Matsuishi, Toshio Kamiya, Masahiro Hirano, Hideo Hosono, Light-induced conversion of an insulating refractory oxide into a persistent electronic conductor, Nature, 10.1038/nature01053, 419, 6906, 462-465, 2002.10, [URL], Materials that are good electrical conductors are not in general optically transparent, yet a combination of high conductivity and transparency is desirable for many emerging opto-electronic applications. To this end, various transparent oxides composed of transition or post-transition metals (such as indium tin oxide) are rendered electrically conducting by ion doping. But such an approach does not work for the abundant transparent oxides of the main-group metals. Here we demonstrate a process by which the transparent insulating oxide 12CaO·7Al2O3 (refs 7-13) can be converted into an electrical conductor. H- ions are incorporated into the subnanometre-sized cages of the oxide by a thermal treatment in a hydrogen atmosphere; subsequent irradiation of the material with ultraviolet light results in a conductive state that persists after irradiation ceases. The photo-activated material exhibits moderate electrical conductivity (∼0.3 S cm-1) at room temperature, with visible light absorption losses of only one per cent for 200-nm-thick films. We suggest that this concept can be applied to other main-group metal oxides, for the direct optical writing of conducting wires in insulating transparent media and the formation of a high-density optical memory..
10.	Katsuro Hayashi, Masahiro Hirano, Satoru Matsuishi, Hideo Hosono, Microporous crystal 12CaO·7Al2O3 encaging abundant O- radicals, Journal of the American Chemical Society, 10.1021/ja016112n, 124, 5, 738-739, 2002.02, [URL], Extremely high concentrations (>1020 cm-3) of active oxygenic radicals, O- and O2 -, have been created in the zeolitic crystal, 12CaO·7Al2O3 (C12A7), which can accommodate anions in its cavities. An increase in oxygen pressure and a decrease in water vapor pressure at high temperature enhance the formation of the radicals. The oxidation of Pt is observed on the surface of the material as a result of reaction with the active oxygens..
11.	Katsuro Hayashi, Takahisa Yamamoto, Taketo Sakuma, Grain orientation dependence of the PTCR effect in niobium-doped barium titanate, Journal of the American Ceramic Society, 10.1111/j.1151-2916.1996.tb08780.x, 79, 6, 1669-1672, 1996.04, [URL], The positive temperature coefficient of resistivity (PTCR) effect is directly measured in single grain boundaries in 0.1-mol%-Nb-doped BaTiO3 with 1 mm coarse grains. The PTCR effect largely depends on grain boundary structure. Random grain boundaries exhibit the PTCR effect as in polycrystalline samples, but the PTCR effect does not appear in highly coherent boundaries such as small-angle boundaries, twin boundaries, and coincidence site lattice (CSL) boundaries with low ∑ values. For ∑= 3 boundaries, the resistance increase above the Curie temperature is a function of deviation angle. A small PTCR effect is observed in ∑ = 3 boundaries with a deviation angle of about 9° in contrast with ideal ∑ = 3 boundaries and boundaries with a deviation of about 4°..

主要総説, 論評, 解説, 書評, 報告書等

主要学会発表等

1.	林　克郎, 還元性熱処理による酸化物ホストへの水素化物イオン導入, 第65回応用物理学会, 2018.03.
2.	林　克郎, マイエナイト結晶を起点とした活性アニオンの評価と機能発現, 日本セラミックス協会第30回秋季シンポジウム, 2017.09.
3.	林 克郎, Chemistry of hydride ion and proton in anion-encaging crystals: Mayenite and apatite, Nonstoichiometric Compounds Ⅵ, 2016.09.
4.	林 克郎, セラミックス・セパレータ型ナトリウム系電池への取り組み, 第61回日本化学会中国四国産学連携化学フォーラム, 2015.04.

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