Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 38

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Experimental study of Gamow-Teller transitions via the high-energy-resolution $$^{18}$$O($$^3$$He,$$t$$)$$^{18}$$F reaction; Identification of the low-energy "super" -Gamow-Teller state

Fujita, Hirohiko*; Fujita, Yoshitaka*; Utsuno, Yutaka; Yoshida, Kenichi*; Adachi, Tatsuya*; Algora, A.*; Csatl$'o$s, M.*; Deaven, J. M.*; Estevez-Aguado, E.*; Guess, C. J.*; et al.

Physical Review C, 100(3), p.034618_1 - 034618_13, 2019/09

 Times Cited Count:2 Percentile:52.25(Physics, Nuclear)

no abstracts in English

Journal Articles

Ecological and genomic profiling of anaerobic methane-oxidizing archaea in a deep granitic environment

Ino, Kohei*; Hernsdorf, A. W.*; Konno, Yuta*; Kozuka, Mariko*; Yanagawa, Katsunori*; Kato, Shingo*; Sunamura, Michinari*; Hirota, Akinari*; Togo, Yoko*; Ito, Kazumasa*; et al.

ISME Journal, 12(1), p.31 - 47, 2018/01

 Times Cited Count:26 Percentile:5.14(Ecology)

In this study, we found the dominance ofanaerobic methane-oxidizing archaea in groundwater enriched in sulfate and methane from a 300-m deep underground borehole in granitic rock.

Journal Articles

Deep microbial life in high-quality granitic groundwater from geochemically and geographically distinct underground boreholes

Ino, Kohei*; Konno, Yuta*; Kozuka, Mariko*; Hirota, Akinari*; Togo, Yoko*; Fukuda, Akari*; Komatsu, Daisuke*; Tsunogai, Urumu*; Tanabe, Akifumi*; Yamamoto, Satoshi*; et al.

Environmental Microbiology Reports (Internet), 8(2), p.285 - 294, 2016/04

 Times Cited Count:16 Percentile:32.63(Environmental Sciences)

To understand the subsurface biosphere, borehole investigation was conducted for 300-m deep granitic rocks at the Mizunami underground research laboratory, Japan. The initial biomass was the highest with the flourish of aerobic H$$_{2}$$-oxidizing Hydrogenophaga spp., whereas an uncultivated lineage of the phylum Nitrospirae became predominant after three years with decreasing biomass. The common occurrence of many species of Nitrospirae and Chlorobi phyla at the geographically distinct sites and the exclusive detection of their phylogenetically related environmental sequences from deep groundwaters and terrestrial hot springs, suggest that these bacteria are indigenous and potentially adapted to the deep terrestrial subsurface.

Journal Articles

Biogeochemical signals from deep microbial life in terrestrial crust

Suzuki, Yohei*; Konno, Yuta*; Fukuda, Akari*; Komatsu, Daisuke*; Hirota, Akinari*; Watanabe, Katsuaki*; Togo, Yoko*; Morikawa, Noritoshi*; Hagiwara, Hiroki; Aosai, Daisuke*; et al.

PLOS ONE (Internet), 9(12), p.e113063_1 - e113063_20, 2014/12

 Times Cited Count:9 Percentile:61.66(Multidisciplinary Sciences)

We present multi-isotopic evidence of microbially mediated sulfate reduction in a granitic aquifer, a representative of the terrestrial crust habitat. Deep groundwater of meteoric origin was collected from underground boreholes drilled into the Cretaceous Toki granite, central Japan. A large sulfur isotopic fractionation of 20-60 permil diagnostic to microbial sulfate reduction is associated with the investigated groundwater containing sulfate below 0.2 mM. In contrast, a small carbon isotopic fractionation ($$<$$ 30 permil) is not indicative of methanogenesis. Our results demonstrate that the deep biosphere in the terrestrial crust is metabolically active and playing a crucial role in the formation of reducing groundwater even under low energy fluxes.

Journal Articles

Damped soft phonons and diffuse scattering in (Bi$$_{1/2}$$Na$$_{1/2}$$)TiO$$_{3}$$

Matsuura, Masato*; Iida, Hiroyuki*; Hirota, Kazuma*; Owada, Kenji; Noguchi, Yuji*; Miyayama, Masaru*

Physical Review B, 87(6), p.064109_1 - 064109_10, 2013/02

 Times Cited Count:24 Percentile:24.52(Materials Science, Multidisciplinary)

Neutron-scattering studies of (Bi$$_{1/2}$$Na$$_{1/2}$$)TiO$$_{3}$$ (BNT) have been performed to elucidate the microscopic mechanism of the broad maximum in the temperature dependence of the dielectric constant at Tm $$sim$$ 600 K and the reduction in the piezoelectric properties above the depolarization temperature, 460 $$sim$$ 480 K. We observed diffuse scattering near the $$Gamma$$ point below 700 K, which competes with the superlattice peak at the M point of the tetragonal phase but coexists with the superlattice peak at the R point of the rhombohedral phase. The diffuse scattering shows an anisotropic Q shape extending along the $$<$$100$$>$$ direction transverse to the scattering vector Q, which is explained by atomic shifts bridging the tetragonal and rhombohedral structures. We propose that the broad maximum in the dielectric constant is associated with a diffusive first-order transition between the competing tetragonal and rhombohedral phases. In addition, we found that the diffuse scattering is reduced for single crystals grown under high oxygen pressure, which suggests an analogy with the central peak in hydrogen-reduced SrTiO$$_{3}$$. Inelastic neutron scattering near the $$Gamma$$ point reveals a heavily overdamped soft mode similar to those reported in lead-based relaxors, the "waterfall" feature. Moreover, a damped soft transverse acoustic mode is observed for the $$<$$100$$>$$ direction as the anisotropic diffuse scattering, indicating phase instabilities with the same origin as that of the diffuse scattering. The recovery of the soft mode is observed near the depolarization temperature, which coincides with the disappearance of the superlattice peak at the M point. These results indicate that the depolarization and the waterfall feature originate in the dynamic nature of ferroelectric clusters in the coexisting tetragonal/rhombohedral phase.

Journal Articles

Effect of B-site randomness on the antiferroelectric/relaxor nature of the ground state; Inelastic X-ray scattering study of Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$

Owada, Kenji; Fukuda, Tatsuo; Mizuki, Junichiro; Hirota, Kazuma*; Terauchi, Hikaru*; Tsutsui, Satoshi*; Baron, A. Q. R.*; Owa, Hidehiro*; Yasuda, Naohiko*

Journal of the Korean Physical Society, 59(3), p.2509 - 2514, 2011/09

 Times Cited Count:2 Percentile:77.99(Physics, Multidisciplinary)

Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) can be antiferroelectric (AFE), ferroelectric (FE) or a relaxor depending upon the perovskite B-site randomness. Orderd PIN (O-PIN, without B-site randomness) is supposed to be an ideal system of lead-based complex perovskite Pb(B'B'')O$$_{3}$$ and expected to give us a clear picture of the AFE/relaxor nature of the ground state by the B-site randomness. We studied the dynamics of O-PIN by inelastic X-ray scattering. The quasielastic (QE) scattering shows the critical slowing down and the transverse acoustic (TA) mode shows the softening towards $$T_{rm N}$$. On the other hand, the transverse optic (TO) mode shows the softening toward low temperature with no clear anomaly at $$T_{rm N}$$. These results represent that the antiferroelectric (AFE) phase transition is associated with the TA and the origin of the QE scattering, while ferroelectric correlation does exist behind the AFE ordering. The effect of B-site randomness is finally discussed on the basis of the results.

Journal Articles

Contribution of intermediate submicrometer structures to physical properties near $$T$$$$_{rm c}$$ in Pb(Zn$$_{1/3}$$Nb$$_{2/3}$$)O$$_{3}$$-9%PbTiO$$_{3}$$PbTiO$$_{3}$$

Owada, 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:7 Percentile:63.66(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(Zn$$_{1/3}$$Nb$$_{2/3}$$)O$$_{3}$$-9%PbTiO$$_{3}$$ 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.

Journal Articles

Magnetic and superconducting properties of CeRhGe$$_2$$ and CePtSi$$_2$$

Hirose, Yusuke*; Nishimura, Naoto*; Honda, Fuminori*; Sugiyama, Kiyohiro*; Hagiwara, Masayuki*; Kindo, Koichi*; Takeuchi, Tetsuya*; Yamamoto, Etsuji; Haga, Yoshinori; Matsuura, Masato*; et al.

Journal of the Physical Society of Japan, 80(2), p.024711_1 - 024711_12, 2011/02

 Times Cited Count:5 Percentile:57.78(Physics, Multidisciplinary)

Journal Articles

Unconventional ferroelectric transition in the multiferroic compound TbMnO$$_{3}$$ revealed by the absence of an anomaly in $$c$$-polarized phonon dispersion

Kajimoto, Ryoichi; Sagayama, Hajime*; Sasai, Kenzo*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Arima, Takahisa*; Hirota, Kazuma*; Mitsui, Yukari*; Yoshizawa, Hideki*; Baron, A. Q. R.*; et al.

Physical Review Letters, 102(24), p.247602_1 - 247602_4, 2009/06

 Times Cited Count:11 Percentile:40.14(Physics, Multidisciplinary)

Journal Articles

Antiferroelectric correlation in relaxor Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ and ferroelectric correlation in antiferroelectric Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Owa, Hidehiro*; Yasuda, Naohiko*

Transactions of the Materials Research Society of Japan, 34(1), p.19 - 22, 2009/03

Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) can be antiferroelectric (AFE), ferroelectric (FE) or a relaxor depending upon the perovskite B-site randomness. This is characterized by measurements of dielectric response, which shows behavior that is usually clearly in one of those three classes. In contrast, X-ray scattering studies suggest the presence of AFE correlation in the relaxor state and FE in AFE state. Weak phonon softening at zone boundary in relaxor state shows that the AFE correlation intrinsically exists in PIN, as does the corresponding elastic scattering at (${it h}$/2 ${it k}$/2 0), while weak diffuse scattering around 333 Bragg reflection appears in AFE state suggesting FE correlation. These results will support our previous speculation that the AFE and FE correlations coexist in PIN (K. Owada ${it et al}$., Phys, Rev. B${bf 77}$ 094136 (2008)). Such a coexistence or competition is widely seen in the perovskite relaxor and the coexistence of FE and AFE correlations is essential for generating relaxor state.

Journal Articles

Intrinsic ferroelectric instability in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ revealed by changing B-site randomness; Inelastic X-ray scattering study

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Owa, Hidehiro*; Yasuda, Naohiko*

Physical Review B, 77(9), p.094136_1 - 094136_8, 2008/03

 Times Cited Count:16 Percentile:40.39(Materials Science, Multidisciplinary)

Antiferroelectric (AFE), ferroelectric (FE) or relaxor states can appear in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) depending upon the perovskite B-site randomness. We studied the effects of this randomness on the dynamics of PIN by high resolution inelastic X-ray scattering using ordered PIN (AFE) and disordered PIN (relaxor) single crystals. We have found a clear softening of a transverse optic mode at the $$Gamma$$ point in both the samples, indicating a robust and intrinsic ferroelectric instability regardless of the actual ground state. We interpret that AFE is stabilized only when In and Nb ions are spatially ordered enough to overwhelm the FE instability. As the B-site randomness becomes larger, AFE is suppressed and the hidden FE state starts appearing. Ultimately, the randomness begins to predominate over the development of FE regions and blocks a long range FE order, which we believe yields polar nanoregions resulting in relaxor behaviors.

Journal Articles

Coherent X-ray diffraction for domain observation

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 Cu$$_{3}$$Au, the ferroelectric material PZN-9%PT (91%Pb(Zn$$_{1/3}$$Nb$$_{2/3}$$)O$$_{3}$$-9%PbTiO$$_{3}$$) and Sr-doped BaTiO$$_{3}$$. 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.

Journal Articles

Spatial distribution of the B-site inhomogeneity in an ${it as-grown}$ Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ single crystal studied by a complementary use of X-ray and neutron scatterings

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Owa, Hidehiro*; Yasuda, Naohiko*

Journal of the Physical Society of Japan, 75(2), p.024606_1 - 024606_6, 2006/12

 Times Cited Count:6 Percentile:56.25(Physics, Multidisciplinary)

Structural properties of ${it as-grown}$ Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) single crystals at room temperature (RT) were investigated by X-ray and neutron scattering techniques, taking much account of the difference in the penetration depth and spatial resolution of X-rays and those of neutrons. A strong diffuse scattering was observed by X-ray while h/4, k/4, 0 superlattice reflections were found by neutron, indicating a relaxor state in the outer-layer of the crystal and an antiferroelectric (AFE) state in the bulk. The phonon dispersion was measured for the first time for the PIN series. Two transverse optic (TO1 and TO2) modes were clarified near the zone center though neither water-fall behavior nor folding of phonon branches was confirmed. We have thus concluded that a major part of the ${it as-grown}$ PIN crystal at RT is ferroelectric (FE). These results imply that the $$B$$-site chemical ordering, i.e. inhomogeneity, which controls the structural properties of PIN, is unevenly distributed throughout the crystal. We speculate that small AFE grains coexist with the FE matrix while the outer-layer is in a relaxor state in the ${it as-grown}$ PIN.

Journal Articles

Neutron and X-ray scattering studies of relaxors

Hirota, Kazuma*; Wakimoto, Shuichi; Cox, D. E.*

Journal of the Physical Society of Japan, 75(11), p.111006_1 - 111006_13, 2006/11

 Times Cited Count:67 Percentile:39.66(Physics, Multidisciplinary)

The extensive and wide-ranging neutron and X-ray scattering studies of relaxors carried out by Gen Shirane and his collaborators are reviewed. Among the many results they have reported in some 50 scientific papers published since 1999, there are three especially notable accomplishments; namely, the discovery of a monoclinic phase near the morphotropic phase boundary, the clarification of the existence and roles of transverse optic soft-mode phonons, and detailed studies of polar nanoregions particularly by diffuse scattering techniques. We will focus mostly on the above topics, and discuss the impact of these on the research and understanding of relaxors.

Journal Articles

Single crystal synchrotron X-ray diffraction study under pressure in UGe$$_{2}$$

Aso, Naofumi*; Owada, Kenji; Watanuki, Tetsu; Machida, Akihiko; Omura, Ayako; Inami, Toshiya; Homma, Yoshiya*; Shiokawa, Yoshinobu*; Hirota, Kazuma*; Sato, Noriaki*

Journal of the Physical Society of Japan, 75(Suppl.), p.88 - 90, 2006/08

no abstracts in English

Journal Articles

Electronic excitations in hole-doped La$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$ studied by resonant inelastic X-ray scattering

Ishii, Kenji; Inami, Toshiya; Owada, Kenji; Kuzushita, Kaori; Mizuki, Junichiro; Murakami, Yoichi; Ishihara, Sumio*; Endo, Yasuo*; Maekawa, Sadamichi*; Hirota, Kazuma*; et al.

Journal of Physics and Chemistry of Solids, 66(12), p.2157 - 2162, 2005/12

 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

We have studied electronic excitations of hole-doped manganese oxides La$$_{1-x}$$Sr$$_x$$MnO$$_3$$ ($$x=0.2$$ and $$0.4$$) by resonant inelastic X-ray scattering at Mn K absorption edge. We observed in the excitation spectra that the Mott gap of La$$_{0.6}$$Sr$$_{0.4}$$MnO$$_{3}$$ was filled by hole-doping. In La$$_{0.8}$$Sr$$_{0.2}$$MnO$$_{3}$$, which shows a metal-insulator transition, we found that temperature dependence of scattering intensity is different between two scattering vectors. It may reflects a anisotropic electronic structure which originates from the orbital degrees of freedom in manganese oxides.

Journal Articles

Resonant inelastic X-ray scattering study of the hole-doped manganites La$$_{1-x}$$Sr$$_x$$MnO$$_3$$ ($$x=0.2$$, $$0.4$$)

Ishii, Kenji; Inami, Toshiya; Owada, Kenji; Kuzushita, Kaori; Mizuki, Junichiro; Murakami, Yoichi; Ishihara, Sumio*; Endo, Yasuo*; Maekawa, Sadamichi*; Hirota, Kazuma*; et al.

Physical Review B, 70(22), p.224437_1 - 224437_6, 2004/12

 Times Cited Count:19 Percentile:33.75(Materials Science, Multidisciplinary)

Electronic excitations in the hole doped manganese oxides (La$$_{1-x}$$Sr$$_x$$MnO$$_3$$, $$x=0.2$$ and $$0.4$$) have been elucidated by using the resonant inelastic X-ray scattering (RIXS) method. A doping effect in the strongly correlated electron systems has been observed for the first time. The scattering spectra show that a salient peak appears in low energies indicating the persistence of the Mott gap. At the same time, the energy gap is partly filled by doping holes and the spectral weight energy shifts toward lower energies. The excitation spectra show little change in the momentum space as is in undoped LaMnO$$_3$$. On the other hand, the scattering intensities in the low energy excitations of $$x=0.2$$ are anisotropic in temperature dependence, which indicates an anisotropy of magnetic interaction and underlying effect of the orbital.

Journal Articles

Neutron diffraction study of field-cooling effects on the relaxor ferroelectric Pb[(Zn$$_{1/3}$$Nb$$_{2/3}$$)$$_{0.92}$$Ti$$_{0.08}$$]O$$_3$$

Owada, Kenji; Hirota, Kazuma*; Rehrig, P. W.*; Fujii, Yasuhiko*; Shirane, Gen*

Physical Review B, 67(9), p.094111_1 - 094111_8, 2003/03

 Times Cited Count:101 Percentile:5.03(Materials Science, Multidisciplinary)

High-temperature ($$T$$) and high-electric-field ($$E$$) effects on Pb[(Zn$$_{1/3}$$Nb$$_{2/3}$$)$$_{0.92}$$Ti$$_{0.08}$$]O$$_{3}$$ (PZN-8%PT) were studied comprehensively by neutron diffraction in the ranges $$300 le T le 550$$~K and $$0 le E le 15$$~kV/cm. We have focused on how phase transitions depend on preceding thermal and electrical sequences. In the field cooling process (FC, $$E parallel [001] ge 0.5$$~kV/cm), a successive cubic (C) $$rightarrow$$ tetragonal (T) $$rightarrow$$ monoclinic (M$$_{rm C}$$) transition was observed. In the zero field cooling process (ZFC), however, we have found that the system does ${em not}$ transform to the rhombohedral (R) phase as widely believed, but to a new, unidentified phase, which we call X. X gives a Bragg peak profile similar to that expected for R, but the $$c$$-axis is always slightly shorter than the $$a$$-axis. As for field effects on the X phase, it transforms into the M$$_{rm C}$$ phase via another monoclinic phase (M$$_{rm A}$$) as expected from a previous report [Noheda ${it et al.}$$ Phys. Rev. B {bf 65}$, 224101 (2002)].

Journal Articles

Orbital excitations in LaMnO$$_3$$ studied by resonant inelastic X-ray scattering

Inami, Toshiya; Fukuda, Tatsuo; Mizuki, Junichiro; Ishihara, Sumio*; Kondo, Hiroshi*; Nakao, Hironori*; Matsumura, Takeshi*; Hirota, Kazuma*; Murakami, Yoichi*; Maekawa, Sadamichi*; et al.

Physical Review B, 67(4), p.045108_1 - 045108_6, 2003/01

 Times Cited Count:56 Percentile:10.79(Materials Science, Multidisciplinary)

We report resonant inelastic x-ray scattering experiments of the orbitally ordered manganite LaMnO$$_3$$. When incident photon energy is tuned near the Mn $$K$$ absorption edge, the spectra reveal three features at 2.5 eV, 8 eV and 11 eV. The 8 eV and 11 eV peaks are ascribed to transitions from the O 2$$p$$ bands to the empty Mn 3$$d$$ and $$4s$$/$$4p$$ bands, respectively. On the other hand, the 2.5 eV peak is considered an orbital excitation across the Mott gap, ${it i.e.}$ an electron excitation from the effective lower Hubbard band with the $$d_{3x^2-r^2}$$ and $$d_{3y^2-r^2}$$ orbital characters to the upper Hubbard band with the $$d_{y^2-z^2}$$ and $$d_{z^2-x^2}$$ ones. The weak dispersion and characteristic azimuthal angle dependence of this excitation are well reproduced by a theory which includes orbital degeneracy and strong electron correlation.

Journal Articles

An Inelastic X-ray scattering spectrometer for materials science on BL11XU at SPring-8

Inami, Toshiya; Fukuda, Tatsuo; Mizuki, Junichiro; Nakao, Hironori*; Matsumura, Takeshi*; Murakami, Yoichi*; Hirota, Kazuma*; Endo, Yasuo*

Nuclear Instruments and Methods in Physics Research A, 467-468(Part.2), p.1081 - 1083, 2001/07

 Times Cited Count:20 Percentile:19(Instruments & Instrumentation)

no abstracts in English

38 (Records 1-20 displayed on this page)