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Ti
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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.
Ichimaru, Satoshi*; Takenaka, Hisataka*; Namikawa, Kazumichi*; Gullikson, E. M.*; Maruyama, Momoko; Oku, Satoshi*
Review of Scientific Instruments, 86(9), p.093106_1 - 093106_7, 2015/09
Times Cited Count：3 Percentile：14.95(Instruments & Instrumentation)A graded and broadband Mo/Si multilayer mirror for EUV spectroscopy is demonstrated. This mirror has an average reflectivity profile of 16% in the wavelength region from 15 nm to 17 nm and an effective area of 1100 - 1500 mm
. This reflectivity is about 4 times larger than that of a standard Mo/Si multilayer mirror on a 1 in. diameter substrate, showing that the mirror can be used for measuring EUV fluorescence at wavelengths in the region around 15 nm to 17 nm.
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.
Kawachi, Tetsuya; Hasegawa, Noboru; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Oba, Toshiyuki; Kaihori, Takeshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; et al.
X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.15 - 24, 2011/12
This paper reviews recent improvement in the source development of laser-driven X-ray lasers and the applications in the research fields of material science, laser processing, X-ray imaging, and radiation damage in biological cells. In the application for material science, we have firstly observed temporal correlation between the domain structures of ferro-electric substance under the Curie temperature. In the laser processing, new X-ray laser interferometer reveals us the nano-scale surface distortion of substance pumped by a femto-second optical pulse. In the X-ray diffraction image, we have taken several static images of micro-structure of samples: now we are trying to extend the objective to nano-scale dynamics using pump and probe method. In the radiation damage of biological cells, we observed double strand break in DNA using X-ray laser exposure; this results are compared with the case using incoherent several KeV X-ray exposure.
Owada, Kenji; Shimomura, Susumu*; Nakao, Hironori*; Matsushita, Mitsuyoshi*; Namikawa, Kazumichi*; Mizuki, Junichiro
Journal of Physics; Conference Series, 320, p.012086_1 - 012086_5, 2011/09
Times Cited Count：0 Percentile：0.03(Physics, Condensed Matter)We have performed an X-ray photon correlation spectroscopy measurement of 91
Pb(ZnNb)O-9PbTiO and found a slow structural fluctuation in time near 
. The slow fluctuation consists of long-term and short-term fluctuations. We have derived the short-term fluctuation from the intensity fluctuations and found out the relaxation time to be an order of 10s. It is suggested that the slow fluctuation is owing to the competition between macroscopic tetragonal symmetry and the microscopic orthorhombic symmetry. The competition should be a main reason for the low-frequency dielectric permittivity.
in Pb(ZnNb)O-9%PbTiOPbTiOOwada, Kenji; Mizuki, Junichiro; Namikawa, Kazumichi*; Matsushita, Mitsuyoshi*; Shimomura, Susumu*; Nakao, Hironori*; Hirota, Kazuma*
Physical Review B, 83(22), p.224115_1 - 224115_7, 2011/06
Times Cited Count：8 Percentile：36.17(Materials Science, Multidisciplinary)Complementary use of coherent X-ray diffraction (CXD), X-ray diffuse scattering, conventional X-ray diffraction techniques and dielectric measurements has enabled us to investigate Pb(ZnNb)O-9%PbTiO with a multiple-length-scale approach from the macroscale (lattice constants, bulk averaged) and microscale to the nanoscale (polar nanoregions (PNRs)) and discuss the contribution of each scale to the dielectric permittivity.
S
Nakao, Hironori*; Owada, Kenji; Shimomura, Susumu*; Ochiai, Akira*; Namikawa, Kazumichi*; Mizuki, Junichiro; Mimura, Hidekazu*; Yamauchi, Kazuto*; Murakami, Yoichi*
AIP Conference Proceedings 1234, p.935 - 938, 2010/06
Times Cited Count：2 Percentile：66.93(Physics, Applied)Owada, Kenji; Namikawa, Kazumichi*; Shimomura, Susumu*; Nakao, Hironori*; Mimura, Hidekazu*; Yamauchi, Kazuto*; Matsushita, Mitsuyoshi*; Mizuki, Junichiro
Japanese Journal of Applied Physics, 49(2), p.020216_1 - 020216_3, 2010/02
Times Cited Count：3 Percentile：14.99(Physics, Applied)Kishimoto, Maki; Namikawa, Kazumichi*; Sukegawa, Kota*; Yamatani, Hiroshi*; Hasegawa, Noboru; Tanaka, Momoko
Review of Scientific Instruments, 81(1), p.013905_1 - 013905_5, 2010/01
Times Cited Count：3 Percentile：18.27(Instruments & Instrumentation)We developed a new soft X-ray speckle intensity correlation spectroscopy system by use of a single shot high brilliant plasma soft X-ray laser. The plasma soft X-ray laser is characterized by several picoseconds in pulse width, more than 90% special coherence, and 10
soft X-ray photons within a single pulse. We developed a Michelson type delay pulse generator using a soft X-ray beam splitter to measure the intensity correlation of X-ray speckles from materials and succeeded in generating double coherent X-ray pulses with picosecond delay times. Moreover, we employed a high-speed soft X-ray streak camera for the picosecond time-resolved measurement of X-ray speckles. We performed the X-ray speckle intensity correlation measurements for probing the relaxation phenomena of polarizations in polarization clusters in the paraelectric phase of the ferroelectric material BaTiO near its Curie temperature and verified its performance.
Owada, Kenji; Namikawa, Kazumichi; Mizuki, Junichiro; Shimomura, Susumu*; Nakao, Hironori*; Ito, Kazuki*; Matsushita, Mitsuyoshi*; Yoneda, Yasuhiro; Murakami, Yoichi*; Hirota, Kazuma*
Transactions of the Materials Research Society of Japan, 32(1), p.7 - 10, 2007/03
An X-ray speckle pattern well reflects a particle or domain alignment on the inside of materials. Detecting the alignment is important for understanding a function of the materials such as ferroelectric, piezoelectric materials, photonic crystals and so on. We have thus constructed the apparatus for coherent X-ray diffraction at BL22XU@SPring-8, high quality slits for obtaining the full coherent X-ray beam, high resolution X-ray CCD camera for obtaining the well-resolved speckle pattern, and so on. By using the devices, we have successfully observed the speckle pattern from CuAu, the ferroelectric material PZN-9%PT (91%Pb(ZnNb)O-9%PbTiO) and Sr-doped BaTiO. The 2DFFT image gives us a spatial autocorrelation function which includes the information of the arrangement of the domains in the crystal within micrometers scale.
Kawachi, Tetsuya; Nagashima, Keisuke; Kishimoto, Maki; Hasegawa, Noboru; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kawazome, Hayato; Tai, R.; Namikawa, Kazumichi*; et al.
Proceedings of SPIE's International Symposium on Optics and Photonics 2005, Vol.5919, p.59190L_1 - 59190L_11, 2005/09
Recent results of the X-ray laser research in Advanced Photon Research (APR) Center in JAERI are reported. In the application of the nickel-like silver laser at a wavelength of 13.9 nm, we report the observation of the microscopic polarization clusters in ferroelectrics material such as BaTi03 by use of the X-ray speckle technique, and other experiments such as photo-ionization of inner-shell electrons are intoroduced. In the development of high quality X-ray laser beam, recently we demonstrated temporally coherent X-ray beam at 23.6 nm, in which the high-order harmonics light was injected into the Ne-like Mn X-ray amplifier. We also mention about the development of new X-ray laser driver laser, which is based on 2 beams of zig-zag slab Nd:glass lasers with 0.1 Hz repetition-rate, and each beam line can provide 10 J output energy, and 1 ps duration.
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.
by means of X-ray lasersTai, R.; Namikawa, Kazumichi*; Kishimoto, Maki; Tanaka, Momoko; Sukegawa, Kota*; Hasegawa, Noboru; Kawachi, Tetsuya; Kado, Masataka; Lu, P.; Nagashima, Keisuke; et al.
Physical Review Letters, 89(25), p.257602_1 - 267602_4, 2002/12
Times Cited Count：40 Percentile：81.14(Physics, Multidisciplinary)no abstracts in English
Kato, Yoshiaki; Daido, Hiroyuki; Nagashima, Keisuke; Kawachi, Tetsuya; Hasegawa, Noboru; Tanaka, Momoko; Tang, H.; Tai, R.; Lu, P.; Kishimoto, Maki; et al.
AIP Conference Proceedings 641, p.31 - 39, 2002/00
no abstracts in English
Mori, K.*; Namikawa, Kazumichi*; *; *; Ando, Masami*
Review of Scientific Instruments, 64(7), p.1825 - 1830, 1993/07
Times Cited Count：5 Percentile：52.92(Instruments & Instrumentation)no abstracts in English
Mori, K.; Namikawa, Kazumichi*; Koyama, Yasuki*; Ando, Masami*
Japanese Journal of Applied Physics, 32(Suppl.32-2), p.323 - 325, 1993/00
no abstracts in English
Mori, K.; Namikawa, Kazumichi*; Koyama, Yasuki*; Ando, Masami*
Photon Factory Activity Report, P. 374, 1992/00
no abstracts in English
Kawachi, Tetsuya; Kishimoto, Maki; Kado, Masataka; Tanaka, Momoko; Hasegawa, Noboru; Ochi, Yoshihiro; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Kunieda, Yuichi; et al.
no journal, ,
Recent progress in X-ray laser research in Japan Atomic Energy Agency is reviewed. Using the nickel-like silver soft X-ray laser at the wavelength of 13.9 nm, the application experiments have been conducted in the research fields such as material science, high-density plasma diagnostics, XRL ablation, XRL imaging using single-shot holography and atomic physics. The repetition rate of the XRL beam has been improved from each 10-20 minutes to 0.1 Hz by using new driver laser system with Nd: glass zigzag slab amplifier, and we are now constructing new beam line for the pump-probe measurement of the surface phase-transition by the method of X-ray laser interferometer. In the research activity on the extension of the wavelength region of the X-ray lasers, firstly, the demonstration of novel coherent X-ray generation by "flying mirror" technique is reported. The second is theoretical investigation of the resonance photo-pumping scheme toward water-window region.
Owada, Kenji; Namikawa, Kazumichi; Mizuki, Junichiro; Matsushita, Mitsuyoshi*; Shimomura, Susumu*; Nakao, Hironori*; Hirota, Kazuma*
no journal, ,
no abstracts in English
Owada, Kenji; Mizuki, Junichiro; Namikawa, Kazumichi*; Matsushita, Mitsuyoshi*; Shimomura, Susumu*; Nakao, Hironori*; Hirota, Kazuma*
no journal, ,
