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3. Selective Hydride Interstitials Induced in a High-Entropy Lanthanide Oxyhydride

Author

Vaishnav, Yuvraj, Rai, Rohit K., Al Maksoud, Walid, Takeiri, Fumitaka, Hayama, Shusaku, Yaguchi, Hiroshi, Ould-Chikh, Samy, Toth, Marcell, Bacha, Raza Ullah Shah, Davaasuren, Bambar, Avdeev, Maxim, Kobayashi, Genki, and Kobayashi, Yoji

Abstract

High-entropy materials have gained significant interest in many applications, but structural investigations of the effect on anions in the crystal structure are still scarce. Here, we study the effect of multicomponent cation disorder in the case of mixed-anion compounds. The distribution of mixed anions among various coordination sites is important given their implications for properties such as ionic conductivity and bulk diffusion in catalysis. Structural analysis in the fluorite-type (La,Ce,Pr,Nd,Y)H1.5O0.75reveals that the disordered cationic effects create new interstitial sites, occupied selectively by hydride despite oxide and hydride disorder in other compositions and sites. In contrast, single-lanthanide oxyhydrides of analogous anion content, such as LaH1.5O0.75, or SmH2O0.5lack the complex interstitial structure. Hydride ion conductivity measurements and bond valence sum energy maps show a considerably low activation energy of hydride migration due to the additional interstitial sites induced by high entropy. Such interstitials can be crucial in applications that involve hydride ion diffusion, such as ammonia synthesis catalysis and solid-state ionics, as further high-entropy compositions are explored.

Published
2024
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5. High H– Conductivities along the ab-Planes of La2LiHO3 Epitaxial Thin Films

Author

Sasahara, Yuki, primary, Hirose, Takashi, additional, Yoshimoto, Masataka, additional, Matsui, Naoki, additional, Kobayashi, Shigeru, additional, Ubukata, Hiroki, additional, Takeiri, Fumitaka, additional, Suzuki, Kota, additional, Hirayama, Masaaki, additional, Nishio, Kazunori, additional, Shimizu, Ryota, additional, Kanno, Ryoji, additional, Kobayashi, Genki, additional, and Hitosugi, Taro, additional

Published
2023
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7. Illustrating the Basic Functioning of Mass Analyzers in Mass Spectrometers with Ball-Rolling Mechanisms

Author

Horikoshi, Ryo, Takeiri, Fumitaka, Mikita, Riho, Kobayashi, Yoji, and Kageyama, Hiroshi

Abstract

A unique demonstration with ball-rolling mechanisms has been developed to illustrate the basic principles of mass analyzers as components of mass spectrometers. Three ball-rolling mechanisms mimicking the currently used mass analyzers (i.e., a quadrupole mass filter, a magnetic sector, and a time-of- flight) have been constructed. Each mechanism was designed to separate balls with three different weights (representing three ionized analytes with different weights) in an attempt to imitate the separation process employed by real mass analyzers. This demonstration helped students understand the basic principles of mass analyzers.

Published
2017
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8. Strain-induced creation and switching of anion vacancy layers in perovskite oxynitrides

Author

Yamamoto, Takafumi, Chikamatsu, Akira, Kitagawa, Shunsaku, Izumo, Nana, Yamashita, Shunsuke, Takatsu, Hiroshi, Ochi, Masayuki, Maruyama, Takahiro, Namba, Morito, Sun, Wenhao, Nakashima, Takahide, Takeiri, Fumitaka, Fujii, Kotaro, Yashima, Masatomo, Sugisawa, Yuki, Sano, Masahito, Hirose, Yasushi, Sekiba, Daiichiro, Brown, Craig M., Honda, Takashi, Ikeda, Kazutaka, Otomo, Toshiya, Kuroki, Kazuhiko, Ishida, Kenji, Mori, Takao, Kimoto, Koji, Hasegawa, Tetsuya, and Kageyama, Hiroshi

Published
2020
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10. Exploring the Gas Chemistry of Old Submarine Technologies Using Plastic Bottles as Reaction Vessels and Models

Author

Horikoshi, Ryo, Takeiri, Fumitaka, and Kobayashi, Yoji

Abstract

We describe an activity that is suitable for high school students and makes use of plastic bottles. This activity allows students to familiarize themselves with gas chemistry by introducing technologies that were applied in old submarine systems. Plastic bottles, which are representative of submarines, are used as reaction vessels. Three simple experiments regarding gas chemistry are carried out in the plastic bottles: (1) a carbon dioxide absorption reaction using soda lime, which mimics an air-cleaning canister; (2) a chlorine and hydrogen evolution reaction by the electrolysis of brine, which highlights the accidental generation of gases by lead batteries on board submarines; and (3) a catalytic hydrogen peroxide decomposition that exists in submarine propulsion system. To introduce an antisonar countermeasure system outside the submarine, a fourth experiment on hydrogen generation by the reaction of calcium hydride and water is also conducted.

Published
2016
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11. Electropositive Metal Doping into Lanthanum Hydride for H− Conducting Solid Electrolyte Use at Room Temperature.

Author

Izumi, Yoshiki, Takeiri, Fumitaka, Okamoto, Kei, Saito, Takashi, Kamiyama, Takashi, Kuwabara, Akihide, and Kobayashi, Genki

Subjects
*SOLID electrolytes, *FUEL cell efficiency, *LANTHANUM, *CONDUCTION electrons, *ENERGY density, *HYDROGEN as fuel, *HYDRIDES
Abstract

Hydride ion conductors have made remarkable progress in recent years; in particular, the fluorite‐type LaH3‐δ series exhibits high conductivity around room temperature. However, its intrinsic character of hydrogen non‐stoichiometry still makes its application as a solid electrolyte challenging, for which high electronic insulation is essential. Here, Sr‐substituted LaH3‐δ with slight O2− incorporation, represented as La1‐xSrxH3‐x‐2yOy (0.1 ≤ x ≤ 0.6, y ≤ 0.171), is synthesized, which exhibits H− conductivity of 10−4 – 10−5 S cm−1 at room temperature. The galvanostatic discharge reaction using an all‐solid‐state cell composed of Ti|La1‐xSrxH3‐x‐2yOy|LaH3‐δ shows that the Ti electrode is completely hydrogenated to TiH2 for x ≥ 0.2, whereas a short circuit occurs for x = 0.1. These experimental observations, together with calculation studies on the density of states and the defect formation energy, provide clear evidence that electropositive cation, such as Sr, doping critically suppresses the electron conduction in LaH3‐δ. Achieving a superior H− conducting solid electrolyte is a novel milestone in the development of electrochemical devices that utilize its strong reducing ability (E°(H−/H2) = −2.25 V vs SHE), such as batteries with high energy density and electrolysis/fuel cells with high efficiency. [ABSTRACT FROM AUTHOR]

Published
2023
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12. A new family of anti-perovskite oxyhydrides with tetrahedral GaO4 polyanions.

Author

Ayu, Nur Ika Puji, Takeiri, Fumitaka, Ogawa, Takafumi, Kuwabara, Akihide, Hagihala, Masato, Saito, Takashi, Kamiyama, Takashi, and Kobayashi, Genki

Subjects
*POLYANIONS, *BAND gaps, *X-ray powder diffraction, *EXCHANGE reactions, *PEROVSKITE, *TETRAHEDRAL molecules, *RAW materials
Abstract

New solid compounds A3−xGaO4H1−y (A = Sr, Ba; x ∼0.15, y ∼0.3), which are the first oxyhydrides containing gallium ions, have been synthesized by high-pressure synthesis. Powder X-ray and neutron diffraction experiments revealed that the series adopts an anti-perovskite structure consisting of hydride-anion-centered HA6 octahedra with tetrahedral GaO4 polyanions, wherein the A- and H-sites show partial defect. Formation energy calculations from the raw materials support that stoichiometric Ba3GaO4H is thermodynamically stable with a wide band gap. Annealing the A = Ba powder under flowing Ar and O2 gas suggests topochemical H− desorption and O2−/H− exchange reactions, respectively. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Recent Progress on Mixed-Anion Materials for Energy Applications

Author

Maeda, Kazuhiko, primary, Takeiri, Fumitaka, additional, Kobayashi, Genki, additional, Matsuishi, Satoru, additional, Ogino, Hiraku, additional, Ida, Shintaro, additional, Mori, Takao, additional, Uchimoto, Yoshiharu, additional, Tanabe, Setsuhisa, additional, Hasegawa, Tetsuya, additional, Imanaka, Nobuhito, additional, and Kageyama, Hiroshi, additional

Published
2022
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18. Impact of Na Concentration on the Phase Transition Behavior and H− Conductivities in the Ba–Li–Na–H–O Oxyhydride System.

Author

Okamoto, Kei, Takeiri, Fumitaka, Imai, Yumiko, Yonemura, Masao, Saito, Takashi, Ikeda, Kazutaka, Otomo, Toshiya, Kamiyama, Takashi, and Kobayashi, Genki

Subjects
*PHASE transitions, *SUPERIONIC conductors, *DIFFERENTIAL scanning calorimetry, *HYDRIDES, *BARIUM
Abstract

K2NiF4‐type Ba–Li oxyhydride (BLHO) transitions to a so‐called hydride superionic conductor, exhibiting a high and essentially temperature‐independent hydride ion (H−) conductivity over 0.01 S cm−1 through the disordering of H− vacancies above 300 °C. In this study, a Ba–Li–Na–H–O oxyhydride system synthesized in which lithium is partially substituted with sodium in BLHO and investigated the effects of Na content on the phase transition behavior and the conductivity. Structural refinements and differential scanning calorimetry experiments confirmed a lowering trend in the phase transition temperatures and decreasing enthalpy changes for the transition with increasing Na content. Substitution of not <40% of Li with Na lowered the degree of ordered vacancies at the H− sites at room temperature and improved conductivities by more than two orders of magnitude in the low‐temperature region (T < 300 °C) before the phase transition. These findings clearly show that introducing Na into the lattice effectively stabilizes the high‐conductive phase of BLHO. [ABSTRACT FROM AUTHOR]

Published
2023
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19. Anion ordering enables fast H − conduction at low temperatures

Author

Ubukata, Hiroki, Takeiri, Fumitaka, Shitara, Kazuki, Tassel, Cédric, Saito, Takashi, Kamiyama, Takashi, Broux, Thibault, Kuwabara, Akihide, Kobayashi, Genki, and Kageyama, Hiroshi

Subjects
Multidisciplinary, Materials science, Hydrogen, Hydride, Materials Science, SciAdv r-articles, chemistry.chemical_element, Ionic bonding, 02 engineering and technology, Conductivity, 010402 general chemistry, 021001 nanoscience & nanotechnology, Thermal conduction, 01 natural sciences, 0104 chemical sciences, Ion, Chemistry, chemistry, Chemical physics, Ionic conductivity, Hexagonal lattice, 0210 nano-technology, Research Articles, Research Article
Abstract

The introduction of chemical disorder by substitutional chemistry into ionic conductors is the most commonly used strategy to stabilize high-symmetric phases while maintaining ionic conductivity at lower temperatures. In recent years, hydride materials have received much attention owing to their potential for new energy applications, but there remains room for development in ionic conductivity below 300°C. Here, we show that layered anion-ordered Ba2−δH3−2δX (X = Cl, Br, and I) exhibit a remarkable conductivity, reaching 1 mS cm⁻¹ at 200°C, with low activation barriers allowing H⁻ conduction even at room temperature. In contrast to structurally related BaH2 (i.e., Ba2H4), the layered anion order in Ba2−δH3−2δX, along with Schottky defects, likely suppresses a structural transition, rather than the traditional chemical disorder, while retaining a highly symmetric hexagonal lattice. This discovery could open a new direction in electrochemical use of hydrogen in synthetic processes and energy devices., H¯イオンの低温高速伝導を実現. 京都大学プレスリリース. 2021-06-03., Bringing order to hydrogen energy devices. 京都大学プレスリリース. 2021-06-03.

Published
2021

20. Stabilization of a high H−-conducting phase via K doping of Ba–Li oxyhydride.

Author

Okamoto, Kei, Takeiri, Fumitaka, Imai, Yumiko, Yonemura, Masao, Saito, Takashi, Ikeda, Kazutaka, Otomo, Toshiya, Kamiyama, Takashi, and Kobayashi, Genki

Abstract

We report aliovalent partial substitution of Ba with K in Ba–Li oxyhydride, which exhibits a high H− conductivity caused by structural phase transitions. The phase transition temperatures were decreased by approximately 50 °C via 15% K/Ba substitution, resulting in a high conductivity at lower temperatures. [ABSTRACT FROM AUTHOR]

Published
2022
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23. Anion ordering enables fast H¯ conduction at low temperatures

Author

60597798, 40302640, Ubukata, Hiroki, Takeiri, Fumitaka, Shitara, Kazuki, Tassel, Cédric, Saito, Takashi, Kamiyama, Takashi, Broux, Thibault, Kuwabara, Akihide, Kobayashi, Genki, Kageyama, Hiroshi, 60597798, 40302640, Ubukata, Hiroki, Takeiri, Fumitaka, Shitara, Kazuki, Tassel, Cédric, Saito, Takashi, Kamiyama, Takashi, Broux, Thibault, Kuwabara, Akihide, Kobayashi, Genki, and Kageyama, Hiroshi

Published
2021

26. Strain-induced creation and switching of anion vacancy layers in perovskite oxynitrides

Author

50722211, 60585602, 40302640, Yamamoto, Takafumi, Chikamatsu, Akira, Kitagawa, Shunsaku, Izumo, Nana, Yamashita, Shunsuke, Takatsu, Hiroshi, Ochi, Masayuki, Maruyama, Takahiro, Namba, Morito, Sun, Wenhao, Nakashima, Takahide, Takeiri, Fumitaka, Fujii, Kotaro, Yashima, Masatomo, Sugisawa, Yuki, Sano, Masahito, Hirose, Yasushi, Sekiba, Daiichiro, Brown, Craig M., Honda, Takashi, Ikeda, Kazutaka, Otomo, Toshiya, Kuroki, Kazuhiko, Ishida, Kenji, Mori, Takao, Kimoto, Koji, Hasegawa, Tetsuya, Kageyama, Hiroshi, 50722211, 60585602, 40302640, Yamamoto, Takafumi, Chikamatsu, Akira, Kitagawa, Shunsaku, Izumo, Nana, Yamashita, Shunsuke, Takatsu, Hiroshi, Ochi, Masayuki, Maruyama, Takahiro, Namba, Morito, Sun, Wenhao, Nakashima, Takahide, Takeiri, Fumitaka, Fujii, Kotaro, Yashima, Masatomo, Sugisawa, Yuki, Sano, Masahito, Hirose, Yasushi, Sekiba, Daiichiro, Brown, Craig M., Honda, Takashi, Ikeda, Kazutaka, Otomo, Toshiya, Kuroki, Kazuhiko, Ishida, Kenji, Mori, Takao, Kimoto, Koji, Hasegawa, Tetsuya, and Kageyama, Hiroshi

Abstract

Perovskite oxides can host various anion-vacancy orders, which greatly change their properties, but the order pattern is still difficult to manipulate. Separately, lattice strain between thin film oxides and a substrate induces improved functions and novel states of matter, while little attention has been paid to changes in chemical composition. Here we combine these two aspects to achieve strain-induced creation and switching of anion-vacancy patterns in perovskite films. Epitaxial SrVO3 films are topochemically converted to anion-deficient oxynitrides by ammonia treatment, where the direction or periodicity of defect planes is altered depending on the substrate employed, unlike the known change in crystal orientation. First-principles calculations verified its biaxial strain effect. Like oxide heterostructures, the oxynitride has a superlattice of insulating and metallic blocks. Given the abundance of perovskite families, this study provides new opportunities to design superlattices by chemically modifying simple perovskite oxides with tunable anion-vacancy patterns through epitaxial lattice strain.

Published
2020

27. Theoretical band structure of the superconducting antiperovskite Sr₃₋ₓ SnO

Author

Ikeda, Atsutoshi, Fukumoto, Toshiyuki, Oudah, Mohamed, Hausmann, Niklas Jan, Yonezawa, Shingo, Kobayashi, Shingo, Sato, Masatoshi, Tassel, Cedric, Takeiri, Fumitaka, Takatsu, Hiroshi, Kageyama, Hiroshi, and Maeno, Yoshiteru

Subjects
Superconductivity, First-principles band calculation, Inverse perovskite oxide, Antiperovskite oxide
Abstract

In order to investigate the position of the strontium deficiency in superconductive Sr₃₋ₓ SnO, we synthesized and measured X-ray-diffraction patterns of Sr₃₋ₓ SnO (x ~ 0.5). Because no clear peaks originating from superstructures were observed, strontium deficiency is most likely to be randomly distributed. We also performed first-principles band-structure calculations on Sr₃₋ₓ SnO (x = 0, 0.5) using two methods: full-potential linearized-augmented plane-wave plus local orbitals method and the Korringa-Kohn-Rostoker Green function method combined with the coherent potential approximation. We revealed that the Fermi energy of Sr₃₋ₓ SnO in case of x ~ 0.5 is about 0.8 eV below the original Fermi energy of the stoichiometric Sr₃SnO, where the mixing of the valence p and conduction d orbitals are considered to be small.

Published
2018

30. Luminescent ionic liquid formed from a melted rhenium(v) cluster

Author

Yanagisawa, Junichi, primary, Hiraoka, Tomoaki, additional, Kobayashi, Fumiya, additional, Saito, Daisuke, additional, Yoshida, Masaki, additional, Kato, Masako, additional, Takeiri, Fumitaka, additional, Kobayashi, Genki, additional, Ohba, Masaaki, additional, Lindoy, Leonard F., additional, Ohtani, Ryo, additional, and Hayami, Shinya, additional

Published
2020
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31. Single Crystal Growth of Sillén–Aurivillius Perovskite Oxyhalides Bi₄NbO₈X (X = Cl, Br)

Author

Zhong, Chengchao, Kato, Daichi, Takeiri, Fumitaka, Fujii, Kotaro, Yashima, Masatomo, Nishiwaki, Emily, Fujii, Yasuhiro, Koreeda, Akitoshi, Tassel, Cédric, Abe, Ryu, and Kageyama, Hiroshi

Subjects
melt growth, single crystal growth, photocatalyst, Sillén–Aurivillius compounds
Abstract

Sillén–Aurivillius perovskite Bi₄NbO₈X (X = Cl, Br) is a promising photocatalyst for water splitting under visible light, as well as a potential ferroelectric material. In this work, we investigate the crystal growth conditions by mainly varying soak temperature, soak time and cooling rate. Under the optimal conditions, we successfully obtained yellow platelet single crystals with an in-plane distance of several hundred microns. As opposed to conventional crystal growth, a moderate cooling is essential to suppress an evaporation of the Bi–O–Cl species from a melt zone. The single crystals of Bi4NbO8Br were also grown using a similar condition. We suggest that the knowledge obtained in this study can be generally applied to other Sillén–Aurivillius phases and related oxyhalides

Published
2018

35. Theoretical band structure of the superconducting antiperovskite Sr₃₋ₓ SnO

Author

30523584, 30313117, 60597798, 60585602, 40302640, Ikeda, Atsutoshi, Fukumoto, Toshiyuki, Oudah, Mohamed, Hausmann, Niklas Jan, Yonezawa, Shingo, Kobayashi, Shingo, Sato, Masatoshi, Tassel, Cedric, Takeiri, Fumitaka, Takatsu, Hiroshi, Kageyama, Hiroshi, Maeno, Yoshiteru, 30523584, 30313117, 60597798, 60585602, 40302640, Ikeda, Atsutoshi, Fukumoto, Toshiyuki, Oudah, Mohamed, Hausmann, Niklas Jan, Yonezawa, Shingo, Kobayashi, Shingo, Sato, Masatoshi, Tassel, Cedric, Takeiri, Fumitaka, Takatsu, Hiroshi, Kageyama, Hiroshi, and Maeno, Yoshiteru

Abstract

In order to investigate the position of the strontium deficiency in superconductive Sr₃₋ₓ SnO, we synthesized and measured X-ray-diffraction patterns of Sr₃₋ₓ SnO (x ~ 0.5). Because no clear peaks originating from superstructures were observed, strontium deficiency is most likely to be randomly distributed. We also performed first-principles band-structure calculations on Sr₃₋ₓ SnO (x = 0, 0.5) using two methods: full-potential linearized-augmented plane-wave plus local orbitals method and the Korringa-Kohn-Rostoker Green function method combined with the coherent potential approximation. We revealed that the Fermi energy of Sr₃₋ₓ SnO in case of x ~ 0.5 is about 0.8 eV below the original Fermi energy of the stoichiometric Sr₃SnO, where the mixing of the valence p and conduction d orbitals are considered to be small.

Published
2018

36. Single Crystal Growth of Sillén–Aurivillius Perovskite Oxyhalides Bi₄NbO₈X (X = Cl, Br)

Author

40906921, 60597798, 60356376, 40302640, Zhong, Chengchao, Kato, Daichi, Takeiri, Fumitaka, Fujii, Kotaro, Yashima, Masatomo, Nishiwaki, Emily, Fujii, Yasuhiro, Koreeda, Akitoshi, Tassel, Cédric, Abe, Ryu, Kageyama, Hiroshi, 40906921, 60597798, 60356376, 40302640, Zhong, Chengchao, Kato, Daichi, Takeiri, Fumitaka, Fujii, Kotaro, Yashima, Masatomo, Nishiwaki, Emily, Fujii, Yasuhiro, Koreeda, Akitoshi, Tassel, Cédric, Abe, Ryu, and Kageyama, Hiroshi

Abstract

Sillén–Aurivillius perovskite Bi₄NbO₈X (X = Cl, Br) is a promising photocatalyst for water splitting under visible light, as well as a potential ferroelectric material. In this work, we investigate the crystal growth conditions by mainly varying soak temperature, soak time and cooling rate. Under the optimal conditions, we successfully obtained yellow platelet single crystals with an in-plane distance of several hundred microns. As opposed to conventional crystal growth, a moderate cooling is essential to suppress an evaporation of the Bi–O–Cl species from a melt zone. The single crystals of Bi4NbO8Br were also grown using a similar condition. We suggest that the knowledge obtained in this study can be generally applied to other Sillén–Aurivillius phases and related oxyhalides

Published
2018

38. Synthesis and H− conductivity of a new oxyhydride Ba2YHO3 with anion-ordered rock-salt layers.

Author

Nawaz, Haq, Takeiri, Fumitaka, Kuwabara, Akihide, Yonemura, Masao, and Kobayashi, Genki

Subjects
*X-ray powder diffraction, *HYDRIDES
Abstract

A new layered perovskite oxyhydride Ba2YHO3 was synthesized via high pressure synthesis. Powder X-ray and neutron diffraction experiments revealed that in Ba2YHO3 the ordered H− and O2− anions form [Ba2H2] rock-salt layers wherein H− conduction is allowed. The conductivity reached 0.1 mS cm−1 at 350 °C, which is higher than that of isostructural Ba2ScHO3 with anion-disordered [Ba2HO] layers. [ABSTRACT FROM AUTHOR]

Published
2020
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39. Chemical Pressure-Induced Anion Order–Disorder Transition in LnHO Enabled by Hydride Size Flexibility

Author

Yamashita, Hiroki, primary, Broux, Thibault, additional, Kobayashi, Yoji, additional, Takeiri, Fumitaka, additional, Ubukata, Hiroki, additional, Zhu, Tong, additional, Hayward, Michael A., additional, Fujii, Kotaro, additional, Yashima, Masatomo, additional, Shitara, Kazuki, additional, Kuwabara, Akihide, additional, Murakami, Taito, additional, and Kageyama, Hiroshi, additional

Published
2018
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40. AgFeOF2: A Fluorine-Rich Perovskite Oxyfluoride

Author

Takeiri, Fumitaka, primary, Yamamoto, Takafumi, additional, Hayashi, Naoaki, additional, Hosokawa, Saburo, additional, Arai, Kazunari, additional, Kikkawa, Jun, additional, Ikeda, Kazutaka, additional, Honda, Takashi, additional, Otomo, Toshiya, additional, Tassel, Cédric, additional, Kimoto, Koji, additional, and Kageyama, Hiroshi, additional

Published
2018
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41. Theoretical band structure of the superconducting antiperovskite oxide Sr3−xSnO

Author

Ikeda, Atsutoshi, primary, Fukumoto, Toshiyuki, additional, Oudah, Mohamed, additional, Hausmann, Jan Niklas, additional, Yonezawa, Shingo, additional, Kobayashi, Shingo, additional, Sato, Masatoshi, additional, Tassel, Cédric, additional, Takeiri, Fumitaka, additional, Takatsu, Hiroshi, additional, Kageyama, Hiroshi, additional, and Maeno, Yoshiteru, additional

Published
2018
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45. ZnTaO2N: Stabilized High-Temperature LiNbO3-type Structure

Author

Kuno, Yoshinori, primary, Tassel, Cédric, additional, Fujita, Koji, additional, Batuk, Dmitry, additional, Abakumov, Artem M., additional, Shitara, Kazuki, additional, Kuwabara, Akihide, additional, Moriwake, Hiroki, additional, Watabe, Daichi, additional, Ritter, Clemens, additional, Brown, Craig M., additional, Yamamoto, Takafumi, additional, Takeiri, Fumitaka, additional, Abe, Ryu, additional, Kobayashi, Yoji, additional, Tanaka, Katsuhisa, additional, and Kageyama, Hiroshi, additional

Published
2016
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46. A labile hydride strategy for the synthesis of heavily nitridized BaTiO3

Author

Yajima, Takeshi, Takeiri, Fumitaka, Aidzu, Kohei, Akamatsu, Hirofumi, Fujita, Koji, Yoshimune, Wataru, Ohkura, Masatoshi, Lei, Shiming, Gopalan, Venkatraman, Tanaka, Katsuhisa, Brown, Craig M., Green, Mark A., Yamamoto, Takafumi, Kobayashi, Yoji, and Kageyama, Hiroshi

Subjects
Solid-state chemistry, Ion exchange, Chemistry, Lability, Hydride, General Chemical Engineering, Inorganic chemistry, Photocatalysis, General Chemistry, Neutron scattering, Ferroelectricity, Low mobility
Abstract

Oxynitrides have been explored extensively in the past decade because of their interesting properties, such as visible-light absorption, photocatalytic activity and high dielectric permittivity. Their synthesis typically requires high-temperature NH3 treatment (800-1,300 °C) of precursors, such as oxides, but the highly reducing conditions and the low mobility of N(3-) species in the lattice place significant constraints on the composition and structure-and hence the properties-of the resulting oxynitrides. Here we show a topochemical route that enables the preparation of an oxynitride at low temperatures (

Published
2015

48. Promoted Hydride/Oxide Exchange in SrTiO3by Introduction of Anion Vacancy via Aliovalent Cation Substitution

Author

Takeiri, Fumitaka, Aidzu, Kohei, Yajima, Takeshi, Matsui, Toshiaki, Yamamoto, Takafumi, Kobayashi, Yoji, Hester, James, and Kageyama, Hiroshi

Abstract

We investigated topochemical anion exchange reactions for a ScIII-substituted SrTiIVO3perovskite, Sr(Ti1–yScy)O3–y/2□y/2(y≤ 0.1), using CaH2. It was found that the initial introduction of a small amount of anion vacancies (y/2) is crucial to enhance the anion (H–/O2–) exchangeability. For example, hydride reduction of Sr(Ti0.95Sc0.05)O2.975yielded the oxyhydride SrTi0.95Sc0.05O2.56H0.41in which the hydride concentration is increased by 33% with respect to pristine SrTiO3(leading to SrTiO2.76H0.24). This observation highlights the importance of anion vacancies to improve anion (H–/O2–) diffusion, which is a well-known strategy for improving oxide anion conductivity, and suggests that such a vacancy-assisted reaction could be applied to other anion exchange reactions (e.g., F–/O2–and N3–/O2–) to extend the solubility range.

Published
2024
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50. High‐Pressure Synthesis of Manganese Oxyhydride with Partial Anion Order

Author

Tassel, Cedric, primary, Goto, Yoshinori, additional, Watabe, Daichi, additional, Tang, Ya, additional, Lu, Honcheng, additional, Kuno, Yoshinori, additional, Takeiri, Fumitaka, additional, Yamamoto, Takafumi, additional, Brown, Craig M., additional, Hester, James, additional, Kobayashi, Yoji, additional, and Kageyama, Hiroshi, additional

Published
2016
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