H
Hirofumi Akamatsu
Researcher at Kyushu University
Publications - 82
Citations - 1706
Hirofumi Akamatsu is an academic researcher from Kyushu University. The author has contributed to research in topics: Perovskite (structure) & Amorphous solid. The author has an hindex of 22, co-authored 75 publications receiving 1339 citations. Previous affiliations of Hirofumi Akamatsu include Pennsylvania State University & Kyoto University.
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Journal ArticleDOI
A labile hydride strategy for the synthesis of heavily nitridized BaTiO3.
Takeshi Yajima,Takeshi Yajima,Fumitaka Takeiri,Kohei Aidzu,Hirofumi Akamatsu,Koji Fujita,Wataru Yoshimune,Masatoshi Ohkura,Shiming Lei,Venkatraman Gopalan,Katsuhisa Tanaka,Craig M. Brown,Mark Green,Takafumi Yamamoto,Yoji Kobayashi,Hiroshi Kageyama +15 more
TL;DR: This work shows a topochemical route that enables the preparation of an oxynitride at low temperatures (<500 °C), using a perovskite oxyhydride as a host, and suggests that this 'labile hydride' strategy can be used to explore variousOxynitrides, and perhaps other mixed anionic compounds.
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Antiferromagnetic superexchange via 3d states of titanium in EuTiO3 as seen from hybrid Hartree-Fock density functional calculations
Hirofumi Akamatsu,Yu Kumagai,Fumiyasu Oba,Koji Fujita,Hideo Murakami,Katsuhisa Tanaka,Isao Tanaka +6 more
TL;DR: In this article, a hybrid Hartree-Fock density functional approach was proposed to explain antiferromagnetic and ferromagnetic phases in perovskite oxides, and a superexchange mechanism involving the 3$d$ states of nonmagnetic Ti ions was proposed through first-principles calculations.
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Ferroelectric Sr3Zr2O7 Competition between Hybrid Improper Ferroelectric and Antiferroelectric Mechanisms
Suguru Yoshida,Koji Fujita,Hirofumi Akamatsu,Olivier Hernandez,Arnab Sen Gupta,Forrest G. Brown,Haricharan Padmanabhan,Alexandra S. Gibbs,Toshihiro Kuge,Ryosuke Tsuji,Shunsuke Murai,James M. Rondinelli,Venkatraman Gopalan,Katsuhisa Tanaka +13 more
TL;DR: In this paper, the Ruddlesden-Popper HIF Sr3Zr2O7, which is the first ternary lead-free zirconate ferroelectric, is reported and room-temperature polarization switching is demonstrated.
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Structural characterization of hierarchically porous alumina aerogel and xerogel monoliths.
Yasuaki Tokudome,Kazuki Nakanishi,Kazuyoshi Kanamori,Koji Fujita,Koji Fujita,Hirofumi Akamatsu,Teiichi Hanada +6 more
TL;DR: Small-angle X-ray scattering (SAXS) analysis reveals that variation of median mesopore size can be ascribed to the change in agglomeration state of primary particles, as PEO content and H2O/EtOH ratio increase, secondary particles become small, which results in relatively small mesopores.
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Room-Temperature Polar Ferromagnet ScFeO3 Transformed from a High-Pressure Orthorhombic Perovskite Phase
Takahiro Kawamoto,Koji Fujita,Ikuya Yamada,Tomohiko Matoba,Sung Joo Kim,Peng Gao,Xiaoqing Pan,Scott D. Findlay,Cédric Tassel,Hiroshi Kageyama,Andrew J Studer,James R. Hester,Tetsuo Irifune,Hirofumi Akamatsu,Katsuhisa Tanaka +14 more
TL;DR: LiNbO3-type ScFeO3 is successfully obtained, a metastable phase converted from the orthorhombic perovskite formed under 15 GPa at elevated temperatures, providing a general and versatile strategy to create materials in which ferroelectricity and ferromagnetism coexist at high temperatures.