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-BaTiO solid solutionsYoneda, Yasuhiro; Kim, S.*; Mori, Shigeo*; Wada, Satoshi*
Japanese Journal of Applied Physics, 61(SN), p.SN1022_1 - SN1022_10, 2022/11
Times Cited Count：1 Percentile：17.38(Physics, Applied)Local structural analysis of the (1-
) BiFeO-BaTiO solid solution was performed by PDF analysis of the data obtained in the synchrotron radiation high-energy X-ray diffraction experiment. First, when XAFS experiments were performed and sample screening was performed, it was found that structural fluctuations were large in the BiFeO-rich composition. Therefore, PDF analysis of a sample with BiFeO-rich composition was performed. As a result, it was found that although the average structure is a cubic structure, the local structure can be reproduced with a rhombohedral crystal structure, and there is a displacement that breaks the symmetry of the rhombohedral structure in a composition with a large fluctuation.
through water-soluble Ti complexes as raw material for controlling particle size and distribution of synthesized BaTiO nanocubesNakashima, Koichi*; Hironaka, Kota*; Ouchi, Kazuma*; Ajioka, Mao*; Kobayashi, Yoshio*; Yoneda, Yasuhiro; Yin, S.*; Kakihana, Masato*; Sekino, Toru*
ACS Omega (Internet), 6(48), p.32517 - 32527, 2021/12
Times Cited Count：5 Percentile：38.19(Chemistry, Multidisciplinary)The BaTiO nanoparticles synthesized by the hydrothermal method is examined by synchrotron X-ray and TEM observation. It was found that the particle size of synthesized BaTiO depends on the particle size of the raw material of TiO. Succeeded in synthesizing 100 nm size BaTiO nanocrystals showing uniform particle size distribution using TiO nanoparticles with optimized particle size. The obtained BaTiO nanocrystal is a tetragonal system of ferroelectric phase. A three-dimensional structure of BaTiO nanoparticles could be obtained by the electron beam tomography.
NaTiO in high-temperature phasesYoneda, Yasuhiro; Noguchi, Yuji*
Japanese Journal of Applied Physics, 60(SF), p.SFFA08_1 - SFFA08_10, 2021/11
Times Cited Count：4 Percentile：36.85(Physics, Applied)BiNaTiO (abbreviated as BNT) is a lead-free material but exhibits relatively large piezoelectric properties, a lot of researches have been conducted. We performed local structural analysis using high-quality BNT with a stoichiometrically correct composition, and found a chemical order structure of Bi/Na in locally. BNT undergoes a phase transition to a cubic phase at 400
C. We estimated that a new disorder structure will appear in the high-temperature phase. In the high temperature phase, pair distribution function (PDF) analysis using synchrotron radiation high-energy X-rays was performed. As a result, we found that Bi shifts from 200C, and this shift becomes an order parameter for the phase transition.
nanocubes via precise solvothermal crystal growth and their anomalous surface compositional reconstructionNakashima, Koichi*; Onagi, Kaito*; Kobayashi, Yoshio*; Ishigaki, Toru*; Ishikawa, Yoshihisa*; Yoneda, Yasuhiro; Yin, S.*; Kakihana, Masato*; Sekino, Toru*
ACS Omega (Internet), 6(14), p.9410 - 9425, 2021/04
Times Cited Count：9 Percentile：59.91(Chemistry, Multidisciplinary)We succeeded in synthesizing barium titanate nanocubes by hydrothermal synthesis. When the nanocubes were examined in detail using a scanning electron microscope, pulsed neutrons, and large synchrotron radiation, it was found that a reconstituted layer of titanium oxide was formed on the surface.
Nb
)OYoneda, Yasuhiro; Taniguchi, Hiroki*; Noguchi, Yuji*
Journal of Physics; Condensed Matter, 33(3), p.035401_1 - 035401_8, 2021/01
Times Cited Count：4 Percentile：33.7(Physics, Condensed Matter)Nanoscale structural analysis of relaxor Pb(MgNb)O (PMN) was performed using synchrotron high-energy X-ray diffraction measurements. Although PMN is a well-known relaxor ferroelectric material, the average structure is a cubic structure, and various models have been proposed to explain the ferroelectric microstructure. We performed a wide-range local structure analysis up to 20 nm using the pair distribution function (PDF). As a result, it was found that the structure of PMN changed depending on the distance and it was a glass-like structure.
in high-temperature cubic phaseYoneda, Yasuhiro; Taniguchi, Hiroki*; Kitanaka, Yuki*; Noguchi, Yuji*
Ferroelectrics, 538(1), p.57 - 62, 2019/05
Times Cited Count：5 Percentile：27.39(Materials Science, Multidisciplinary)High-energy X-ray diffraction study was performed on lead titanate (PbTiO). Short-range order structure was revealed using atomic pair-distribution function (PDF) method. In the high-temperature cubic phase, there is a large deviation between local and average structure. Especially, Pb atoms deviated from the cubic lattice framework, but establish Pb-O-Pb random network.
O
Tsukada, Shinya*; Fujii, Yasuhiro*; Yoneda, Yasuhiro; Moriwake, Hiroki*; Konishi, Ayako*; Akishige, Yukikuni*
Physical Review B, 97(2), p.024116_1 - 024116_7, 2018/02
Times Cited Count：19 Percentile：65.6(Materials Science, Multidisciplinary)Uniaxial ferroelectric BaTiO with a Curie temperature 
of 743 K was investigated to clarify its paraelectric-ferroelectric phase transition behavior. The mechanism is discussed on the basis of the structure from short to long ranges determined by synchrotron X-ray diffraction and the lattice dynamics probed by Raman spectroscopy. Using a combination of experimental results and first-principles calculations, we explain the phase transition. Ti vibration of TiO
octahedral units is frozen in the ferroelectric phase and the space group changes from nonpolar 
to polar 
.
and AgNbO
modified by Li substitutionYoneda, Yasuhiro; Aoyagi, Rintaro*; Fu, D.*
Japanese Journal of Applied Physics, 55(10S), p.10TC04_1 - 10TC04_5, 2016/10
Times Cited Count：6 Percentile：29.26(Physics, Applied)We analyzed the local structures of NaNbO and Na
Li
NbO by combining the X-ray absorption fine structure (XAFS) and atomic pair-distribution function (PDF) techniques. NaNbO is known to be an antiferroelectric material at room temperature. It also undergoes a diffuse phase transition, in which an orthorhombic and a rhombohedral phases coexist over a wide temperature range. We identified a rhombohedral ground state structure of NaNbO and assumed an order-disorder-type phase. We also found a disorder feature in the nearest-neighbor bond distance corresponding to the Nb-O bonds. The disordered bond distribution disappeared when Na was substituted for Li. A similar disorder feature was found in AgNbO.
Nb)
Ti
]O crystal near the morphotropic phase boundaryShimizu, Daisuke*; Tsukada, Shinya*; Matsuura, Masato*; Sakamoto, Junya*; Kojima, Seiji*; Namikawa, Kazumichi*; Mizuki, Junichiro; Owada, Kenji
Physical Review B, 92(17), p.174121_1 - 174121_5, 2015/11
Times Cited Count：13 Percentile：50.04(Materials Science, Multidisciplinary)The phase diagram and the relationship between the crystal coherence length and electrical response of Pb[(MgNb)Ti]O (PMN-xPT) near the morphotropic phase boundary (MPB) have been precisely investigated using a single crystal with a Ti composition gradient by synchrotron X-ray diffraction and inelastic light scattering at room temperature. The crystal has two boundaries at Ti compositions of 29.0 mol% and 34.7 mol% which correspond to the phase boundaries between the monoclinic B (MB) and C (MC) phases and between the MC and tetragonal (T) phases, respectively. It is shown that there is a strong negative correlation between the electrical response and the crystal coherence length at the sub-
m scale. The results are explained by the size effects of domains near the MPB.
in the relaxor ferroelectrics (1-x)Pb(ZnNb)O-xPbTiO (
= 0.09) studied by X-ray diffuse scattering and coherent X-ray scatteringOwada, Kenji; Mizuki, Junichiro*; Matsushita, Mitsuyoshi*; Namikawa, Kazumichi*
Physical Review B, 90(10), p.104109_1 - 104109_12, 2014/09
Times Cited Count：6 Percentile：28.17(Materials Science, Multidisciplinary)The paraelectric (PE) to ferroelectric (FE) first-order phase transition of 0.91Pb(ZnNb)O-0.09PbTiO (
= 455 K on cooling) has been studied by the complementary use of X-ray diffuse scattering (XDS) and coherent X-ray scattering (CXS). XDS was mainly used to investigate the FE regions, while CXS was mainly used to investigate the PE regions above on cooling. The diffuse scattering intensity due to the appearance of FE regions shows a maximum at 
K. The diffuse scattering is dynamic in nature and the softening trend changes to a hardening trend at 
. This means that the FE instability is maximum at and therefore the FE regions are well stabilized below 
. The spatial autocorrelation function obtained by CXS, corresponding to the texture of PE regions, starts to rapidly change at about and is most unstable at . We conclude that a heterophase fluctuation occurs between and near the phase transition. The heterophase fluctuation can be expected to correlate to the low-frequency dielectric dispersion and contribute to the phase transition as a precursor phenomenon of the first-order phase transition.
Yoneda, Yasuhiro; Suzuya, Kentaro; Kohara, Shinji*; Mizuki, Junichiro
Ferroelectrics, 339, p.165 - 174, 2006/09
Times Cited Count：1 Percentile：6.64(Materials Science, Multidisciplinary)no abstracts in English
O
Ikeda, Naoshi*; Osumi, Hiroyuki*; Owada, Kenji; Ishii, Kenji; Inami, Toshiya; Kakurai, Kazuhisa; Murakami, Yoichi*; Yoshii, Kenji; Mori, Shigeo*; Horibe, Yoichi*; et al.
Nature, 436(7054), p.1136 - 1138, 2005/08
Times Cited Count：826 Percentile：99.77(Multidisciplinary Sciences)By means of resonant X-ray scattering experiments using synchrotron radiation of SPring-8, it was found that a mixed-valence system LuFeO is a ferroelectric material owing to a real-space charge-ordering of Fe
and Fe
. This ordering is rooted in a charge frustration between the Fe ions on a triangular lattice. The new mechanism of ferroelectricity shown in the present paper offers great potential for designing future ferroelectric devices to be coupled or controlled with the degrees of freedom of electron: charge, spin and orbital.
Yoneda, Yasuhiro; Komura, Yoshiki*; Suzuki, Yoshio*; Hamazaki, Shinichi*; Takashige, Masaaki*; Mizuki, Junichiro
Transactions of the Materials Research Society of Japan, 30(1), p.51 - 54, 2005/03
no abstracts in English
crystalsYoneda, Yasuhiro; Mizuki, Junichiro; Komura, Yoshiki*; Suzuki, Yoshio*; Hamazaki, Shinichi*; Takashige, Masaaki*
Japanese Journal of Applied Physics, 43(9B), p.6821 - 6824, 2004/09
Times Cited Count：9 Percentile：37.43(Physics, Applied)no abstracts in English
Tai, R.; Namikawa, Kazumichi; Sawada, Akikatsu*; Kishimoto, Maki; Tanaka, Momoko; Lu, P.*; Nagashima, Keisuke; Maruyama, Hiroshi*; Ando, Masami*
Physical Review Letters, 93(8), p.087601_1 - 087601_4, 2004/08
Times Cited Count：76 Percentile：89.47(Physics, Multidisciplinary)The polarization clusters existing in both the ferroelectric and the paraelectric phase of BaTiO are directly observed and characterized for the first time by a picosecond soft X-ray laser speckle technique. These dynamic clusters appear continuously across the Curie temperature Tc. The clusters' distance increases approximately linearly with temperature, while their mean size does not change significantly. The polarization exhibits a maximum at a temperature about 5 degree above Tc. The clusters' short-range correlation strength diverges as (T-Tc)
0.41
0.02 as temperature decreases toward Tc.
Nagashima, Keisuke; Tanaka, Momoko; Nishikino, Masaharu; Kishimoto, Maki; Kado, Masataka; Kawachi, Tetsuya; Hasegawa, Noboru; Ochi, Yoshihiro; Sukegawa, Kota*; Tai, R.; et al.
Applied Physics B, 78(7), p.927 - 932, 2004/05
We have succeeded in developing a laser-pumped X-ray laser with full spatial coherence at 13.9 nm. A highly directed X-ray laser beam with the divergence of 0.2 mrad was generated from the double target experiment, where a seeding light from the first laser medium was amplified in the second medium. The observed divergence is close to the diffraction limit value within a factor of two. The seeding light was amplified in the second medium without refraction influence and the gain coefficient was about 8 cm-1. From the measurement of visibility, it was found that the spatial coherent length is longer than the beam diameter. As an application of this coherent X-ray laser, we observed a surface microstructure of ferroelectric material, BaTiO and clarified a change of the microstructure near the Curie temperature.
crystalYoneda, Yasuhiro; Komura, Yoshiki*; Suzuki, Yoshio*; Hamazaki, Shinichi*; Takashige, Masaaki*
Journal of the Physical Society of Japan, 73(4), p.1050 - 1053, 2004/04
We have observed 90 C domain walls in a bulk BaTiO crystal by Synchrotron radiation topography, coupled with a CCD detector. The BaTiO multi-domain crystal was revealed to be strained at the 90 C domain boundary. The polar direction of the BaTiO crystal was tilted by this starin, and this strain also causes the irregular angle of the surface bending mode. The Synchrotron X-ray topography can be performed on a sample with electrodes. The topographic image of the ferroelectric doamin with an electric field clarified that the well-known stripe domain configuration can not be observed without a weak electric field due to the lattice strain at the doamin boundary.
crystalYoneda, Yasuhiro; Komura, Yoshiki*; Suzuki, Yoshio*; Hamazaki, Shinichi*; Takashige, Masaaki*
Journal of the Physical Society of Japan, 73(4), p.1050 - 1053, 2004/04
Times Cited Count：11 Percentile：55.64(Physics, Multidisciplinary)We have observed 90 domain walls in a bulk BaTiO crystal by Synchrotron radiation topography, coupled with a CCD detector. The BaTiO multi-domain crystal was revealed to be strained at the 90 domain boundary. The polar direction of the BaTiO crystal was tilted by this starin, and this strain also causes the irregular angle of the surface bending mode. The Synchrotron X-ray topography can be performed on a sample with electrodes. The topographic image of the ferroelectric doamin with an electric field clarified that the well-known stripe domain configuration can not be observed without a weak electric field due to the lattice strain at the doamin boundary.
Yoneda, Yasuhiro; Mizuki, Junichiro; Katayama, Ryoko*; Yagi, Kenichiro*; Terauchi, Hikaru*; Hamazaki, Shinichi*; Takashige, Masaaki*
Applied Physics Letters, 83(2), p.275 - 277, 2003/07
Times Cited Count：18 Percentile：57.36(Physics, Applied)We observed an intermediate structure during the re-crystallization process from the amorphous state of Bi
TiO
prepared by rapid quenching. The intermediate structure which appears during the re-crystallization process consists of two phases; one is pyrochlore BiTiO
phase and the other is a stacking-fault induced structure under the excessive Bi condition. The microstructure of the stacking-fault induced structure was investigated by synchrotron X-ray diffraction. In the case of a large number of BiO, some are inserted between the pseudo-perovskite layers of BiTiO, and a non-stoichiometric BiWO-like structure is stabilized.
Yoneda, Yasuhiro; Matsumoto, Norimasa; Suzuya, Kentaro; Kohara, Shinji*; Mizuki, Junichiro
Ferroelectrics, 268, p.277 - 282, 2002/00
Times Cited Count：5 Percentile：30.61(Materials Science, Multidisciplinary)no abstracts in English
