研究者総覧

山本 一樹YAMAMOTO Kazukiヤマモト カズキ

所属部署名研究院自然科学系物理学領域
職名教授
Last Updated :2022/10/05

researchmap

プロフィール情報

  • 山本, ヤマモト
  • 一樹, カズキ

学位

  • 博士(工学), 筑波大学
  • 理学修士, 新潟大学

研究分野

  • ナノテク・材料, 無機材料、物性
  • ナノテク・材料, 金属材料物性

経歴

  • 2008年04月, 2012年03月, 奈良女子大学理学部物理科学科 准教授
  • 1998年07月, 2008年03月, 奈良女子大学理学部物理科学科 助教授
  • 1996年01月, 1998年06月, 奈良女子大学理学部物理科学科 助手
  • 1994年10月, 1995年12月, 筑波大学工学研究科 助手
  • 2021年04月, 9999年, 奈良女子大学研究院自然科学系教授
  • 2012年04月, 2021年03月, 奈良女子大学研究院自然科学系准教授

学歴

  • 1991年03月, 1994年09月, 筑波大学, 工学研究科, 物理工学
  • 1989年04月, 1991年03月, 新潟大学, 理学研究科, 物理学専攻
  • 1985年04月, 1989年03月, 新潟大学, 理学部, 物理学科

担当経験のある科目(授業)

  • 物理学実験1(A), 奈良女子大学, 2014年99月99日
  • 物理学特別実験1, 奈良女子大学, 1996年99月99日
  • 物理学特別実験2, 奈良女子大学, 1996年99月99日
  • 物理学基礎実験1, 奈良女子大学, 1996年99月99日
  • 複合自然構造特論Ⅱ, 奈良女子大学
  • 数学物理の歩き方, 奈良女子大学, 2014年99月99日
  • 基礎の物理(A), 奈良女子大学, 2014年99月99日
  • 物理学実験, 奈良女子大学, 1998年20月14日
  • 物理学基礎実験2B, 奈良女子大学
  • 金属電子論セミナー, 奈良女子大学, 2010年99月99日
  • 金属電子論, 奈良女子大学, 2010年99月99日
  • 総合演習E, 奈良女子大学, 2012年
  • 古典物理学概論, 奈良女子大学, 2007年20月13日
  • 回析構造物性論, 奈良女子大学
  • 物理学実験B, 奈良女子大学
  • 環境, 奈良女子大学
  • 回折構造物性論演習, 奈良女子大学
  • 統計処理論, 奈良女子大学, 2013年
  • 結晶物理学, 奈良女子大学, 2015年99月99日
  • 物質環境学総論, 奈良女子大学
  • 物質情報論, 奈良女子大学
  • 物理学基礎実験2A, 奈良女子大学
  • 回折物理学セミナー, 奈良女子大学, 1999年20月09日
  • 回折物理学, 奈良女子大学, 1999年20月09日
  • 物理学実験A, 奈良女子大学, 1998年20月11日
  • 電磁気学演習2, 奈良女子大学, 1996年19月97日
  • 生活と物理, 京都医療技術センター付属看護助産学校, 2006年99月99日
  • 物理学実験, 奈良女子大学, 2013年20月15日
  • 看護物理学, 国立療養所西奈良病院付属看護学校, 1999年20月03日
  • 現代数物概論C, 2021年10月20日
  • 社会に出るまでに知っておきたい科学Ⅱ, 2021年04月20日

所属学協会

  • 日本物理学会
  • 日本結晶学会
  • 日本金属学会

Ⅱ.研究活動実績

論文

  • 査読あり, 英語, MATERIALS TRANSACTIONS, X-ray Study of Phason Strains in an AlCuFeMn Decagonal Phase, Wang Yang; Tomoyo Ando; Kazuki Yamamoto, The peak profiles, shifts, and splittings of Bragg reflections, which are inherent in the phason strain of a quasicrystal, are carefully examined using a precise powder X-ray diffraction method for a wide range of different AlCuFeMn alloys and annealing temperatures. Based on the peak-shift dependences of the Bragg reflections on the phason momentum Q(perpendicular to), two kinds of new approximant phases are identifled. These phases have linear phason strains theta(1) = tau(-6) and theta(2) = tau(-5), and theta(1) = tau(-10) and theta(2) =tau(-5), corresponding to lattice spacings a=3.814 nm and b = 2.005 nm, and a = 9.985 nm and b = 2.005 nm in the quasiperiodic plane of the orthorhombic system, respectively., 2017年, 58, 6, 847, 851
  • 査読あり, 英語, ACTA MATERIALIA, X-ray study of the modulated structure in quenched Ga2Te3 with a defect zinc-blende lattice, Yo Otaki; Yuu Yanadori; Yusuke Seki; Kazuki Yamamoto; Shoji Kashida, Ga2Te3 crystallizes into the zinc-blende Structure. where one-third of the cation sites are vacant. Single-crystal X-ray diffraction studies have been performed on quenched Ga2Te3 crystals. The diffraction maps show. apart From the main zinc-blende-type reflections, satellite reflections at q = (0.060.060.00)(c), where the subscript c indicates the cubic sublattice. Analysis of the satellite reflections shows that the incommensurate structure is two-dimensional. The structure is ascribable to the amplitude-type Modulation caused by Ga vacancies and the coupled displacive modulation of Te atoms, which has a polarization vector along the < 001 >(c) direction. The nature of the atomic modulations is also discussed and the origin of the modulation is attributed to Jahn-Teller-type distortions around Ga vacancies. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved., 2009年03月, 57, 5, 1392, 1398, 研究論文(学術雑誌)
  • 査読あり, 英語, SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, X-ray structural study of the layered compounds CoxNbS2, T Ueno; K Yamamoto; H Matsukura; T Kusawake; K Ohshima, X-ray intensity measurements have been performed on the structure of the layered compound CoxNbS2 single crystals (x <= 0.5) at room temperature. The c-axis lattice parameter changes discontinuously at around x=0.2 and remains constant with further increase of the Co content. For the lower content of Co atoms (x < 0.2), no diffuse maxima appeared on the (hk0) and (hk1) reciprocal lattice planes. At x=0.23, the diffuse maxima are clearly seen at 4/3, 4/3, 1 and 5/3, 5/3, 1 reciprocal lattice points. At -Y=0.32, sharp intensity maxima appear at 4/3, 4/3, 0 and 5/3, 5/3, 0 in addition to at 4/3, 4/3, 1 and 5/3, 5/3, 1. It is understood that root 3 X root(3R0 degrees) ordered structure exists at the stoichiometric composition of x=1/3. At further increasing the Co content, the intensity at 4/3, 4/3, 0 and 5/3, 5/3, 0 is weakening and disappears above x = 0.4. The structural model based on the space group P6(3)22 (No. 182) for CoxNbS2 (x > 0.4) is discussed with considering both the position of the Co atoms and their occupation rate. (c) 2005 Elsevier Ltd. All rights reserved., 2005年09月, 6, 6, 684, 688, 研究論文(学術雑誌)
  • 査読あり, 英語, MATERIALS TRANSACTIONS, Synchrotron X-ray studies of phason and phonon strains in a Co-rich Al-Ni-Co decagonal quasicrystal, K Yamamoto; W Yang; Y Nishimura; N Ikeda; Y Matsuo, Peak broadening and peak shifts of Bragg reflections were studied with the synchrotron single-crystal X-ray diffraction method for an Al72.7Ni8.5Co18.8 decagonal quasicrystal classified as the 5f state. From the Q(perpendicular to) and Q(parallel to) dependences of the full width of half maximum (FWHM) of the Bragg reflections along the longitudinal direction, the coexistence of random phason strains with phonon strains was observed. High-resolution synchrotron X-ray measurements Could present quantitative estimations of these strains. The value of the random phason strain component is 0.0054 similar to tau(-11). The asymmetrical broadening due to the phonon strain shows that the single crystal may be constructed with two kinds of grains that have A(5D) values of 0.6273 and 0.6265 nm., 2004年04月, 45, 4, 1255, 1260, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF ALLOYS AND COMPOUNDS, The successive phase transformation in a Co-rich Al-Ni-Co decagonal phase, K Yamamoto; W Yang; Y Nishimura; Y Matsuo, Peak broadening and the peak positions of Bragg reflections were studied with the high-resolution X-ray diffraction method for decagonal Al72.7Ni8.5Co18.8 quasicrystals. From the Q(perpendicular to) dependences of the full-width at half-maximum (FWHM) of the Bragg reflections and the peak shifts from ideal Bragg peak positions along the longitudinal direction, these decagonal quasicrystals were classified into three groups with different phason strains. These three group, were identified as the random phason strain, the one-dimensional linear phason strain and the two-dimensional linear phason strain, respectively. This means that the Al72.7Ni8.5Co18.8 decagonal phase undergoes a successive phase transformation from a decagonal quasicrystal through a one-dimensional quasicrystal to an approximant crystal. (C) 2002 Elsevier Science B.V. All rights reserved., 2002年08月, 342, 1-2, 237, 240, 研究論文(学術雑誌)
  • 査読あり, 英語, MATERIALS TRANSACTIONS, Growth condition and X-ray analysis of single Al64Cu23Fe13 icosahedral quasicrystal by the Czochralski method, Y Yokoyama; Y Matsuo; K Yamamoto; K Hiraga, Growth conditions for the preparation of a single Al64Cu23Fe13 icosahedral (I-) quasicrystal with excellent quasicrystallinity were examined using the Czochralski method. The appreciation of the quasicrystallinity of the grown single quasicrystal was performed by X-ray structural analysis. The full widths at half-maximum (FWHNI) of the Bragg reflections along 2-, 3- and 5-told symmetry directions have no Q(h) and Q(perpendicular to) dependence. Where the Q(i) and Q(perpendicular to) mean the phason momentum and real scattering vector. Furthermore. peak shifts from ideal Bragg positions were not observed. These means that the grown Al64Cu23Fe13 quasicrystal by the Czochralski method has perfect I-phase structure., 2002年04月, 43, 4, 762, 765, 研究論文(学術雑誌)
  • 査読あり, 英語, MATERIALS TRANSACTIONS, Relationship between phason strain and approximant crystal structure in Co-rich Al-Ni-Co decagonal phase, Y Matsuo; Y Nishimura; K Yamamoto; Y Ishii, Peak broadening and the peak positions of the Bragg reflections were studied with the high-resolution X-ray diffraction method for the decagonal Al72.7Ni8.5Co18.8 quasicrystal. The full-widths at half-maximum (FWHM) of the Bragg reflections along the longitudinal direction (L), which is perpendicular to the periodic axis, have no Q(parallel to) or Q(perpendicular to) dependences. On the other hand, notable peak shifts from ideal Bragg peak positions with linear Q, dependence were observed. This means that the Al72.7Ni8.5Co18.8 decagonal phase has linear phason strains. According to the absolute values of the linear phason strains, the transformation from the decagonal phase to an approximant crystal is discussed., 2001年09月, 42, 9, 2008, 2012, 研究論文(学術雑誌)
  • 査読あり, 英語, PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES, X-ray diffraction study of a phason strain in an Al-Cu-Fe icosahedral quasicrystal, M Jono; Y Matsuo; K Yamamoto; Y Ishii, Detailed examinations of the peak profiles and the positions of the Bragg peaks are carried out with the X-ray diffractometer for single-grain samples of the Al-Cu-Fe icosahedral quasicrystal. Notable peak shifts from the ideal positions with linear Q(perpendicular to) dependence are observed along the fivefold directions. This means that the sample contains linear phason strain. The amplitude of the linear phason strain is estimated as -0.0543, which is close to a theoretical value for the phason-strain-inducing transformation from the icosahedral phase to the pentagonal phase (P2 phase), -1/tau (6). The two-dimensional intensity distributions around the Bragg peaks on the twofold, threefold and fivefold axes are interpreted as consequences of the phason-strain-inducing pentagonal deformation., 2001年11月, 81, 11, 2577, 2590, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, X-ray study of the electron density distribution for Al6Mn, K Yamamoto; Y Matsuo, The electron density distribution of Al6Mn has been studied by a single-crystal x-ray diffraction method. The maximum-entropy method (MEM) is used to construct the electron density distribution (EDD). In the EDD maps, strong covalent bonds between Al atoms and Mn atoms are visible. The number of electrons belonging to each atom and the charge transfer from AI atoms to an Mn atom have been derived from the EDD maps. The negative valence was estimated to be -1.46 for an Mn atom. This negative valence can be understood to be the charge transfer due to the covalent bond with a strong ionic character. These results were compared with pair-potential calculations and band-structure calculations., 2000年03月, 12, 11, 2359, 2365, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, X-ray study of the electron density distributions for hexagonal Al5Co2 and Al10Mn3, K Yamamoto; M Jono; Y Matsuo, The electron density distributions of Al5Co2 and Al10Mn3, which include icosahedral clusters, have been studied by a single-crystal x-ray diffraction method. The maximum-entropy method (MEM) is used to construct the electron density distribution (EDD). In the EDD maps, strongly covalent bonds between Al atoms and transition metal (TM) atoms are visible. As regards the chemical bonding, Al10Mn3 has an icosahedral bonding environment, whereas Al5Co2 does not. The number of electrons belonging to each atom and the charge transfer from Al atoms to TM atoms have been derived from the EDD maps. The negative valences were estimated to be -1.25 and -1.26 for Co atoms and -1.00 for a Mn atom. These negative valences can be understood to be the charge transfer due to the covalent bond with strongly ionic character. These results were compared with pair-potential calculations and band-structure calculations., 1999年02月, 11, 4, 1015, 1026, 研究論文(学術雑誌)
  • 査読あり, 英語, MATERIALS TRANSACTIONS JIM, X-ray diffraction study of the decagonal Al70Ni10Co20, Y Matsuo; N Sugiyama; K Yamamoto, A decagonal Al70Ni10Co20 single quasicrystal was studied with high-resolution X-ray diffraction. Full-widths at half-maximum (FWHM) of Bragg reflections along the longitudinal direction (L) monotonically increase with increasing of Q(perpendicular to). This result suggests that the Al70Ni10Co20 decagonal phase has random phason strain. On the other hand, FWHM for both transverse directions T1 and T2, which are perpendicular to the L-direction in an aperiodic plane (T1) and along a periodic direction (T2), have linear Q(parallel to) dependence. So the single crystal has some distortion of mosaics. Notable peak shifts from ideal Bragg peak positions were not observed., 1999年02月, 40, 2, 137, 140, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, Investigation of phason strains in decagonal Al-Pd-Mn single quasicrystals by means of x-ray diffraction, Y Matsuo; K Yamamoto; Y Ishii, A careful examination of the peak profiles, peak shifts and peak separations of Bragg reflections, which are inherent in the disordering of quasicrystal, is carried out using an x-ray diffraction method for decagonal Al-Pd-Mn single quasicrystals. The full widths at half-maximum (FWHM) of the Bragg reflections along the longitudinal direction (L) have no Q(parallel to)- or Q(perpendicular to)-dependence whereas those for both transverse directions, which are perpendicular to the L direction in an aperiodic plane and with a periodic axis, have linear Q(parallel to)-dependence. Notable peak shifts and separations of Bragg reflections are observed. The absolute values of the shifts are found to be proportional to Q(perpendicular to). The peak shifts and separations are analysed in terms of linear phason strains., 1998年02月, 10, 5, 983, 994, 研究論文(学術雑誌)
  • 査読あり, 英語, Proceedings of the 6th International Conference on Quasicrystals, X-ray Diffuse Scattering in the Al-Pd-Mn Decagonal Quasicrystal, 山本一樹, 1998年, 403
  • 査読あり, 英語, JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, X-ray fluorescence analysis of rare-earth atoms in materials by use of ultrashort wavelength X-rays, Y Takahashi; K Yamamoto; K Ohshima; K Yukino; FP Okamura, A new technique of X-ray fluorescence analysis using ultrashort-wavelength X-rays was tested to obtain the K-series of spectra for rare-earth elements in two different kinds of materials, i.e. powder samples of rare-earth oxides and single crystals of rare-earth hexaborides. This technique utilizes a solid-state detector and multichannel pulse-height analyzer, and satisfies the requirements for quantitative identification in samples containing heavy elements. This technique was applied to determine the composition of the mixed compound La1-xCexB6 (z = 0.25, 0.50 and 0.75). There is good agreement, within the limits of experimental error, between the values thus obtained and the nominal values., 1998年05月, 37, 5A, L556, L558, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, An observation of localized 3d electron density distribution of Fe3O4, Y Kino; FP Okamura; K Yamamoto; K Siratori, Measurement of X-ray diffraction data using WK alpha (lambda = 0.20889 Angstrom) radiation was carried out on Fe3O4 at room temperature. Data were analyzed using the maximum entropy method (MEM). The electron density distribution of the (1 0 0) and (1 1 0) planes of Fe3O4 are examined in detail. Electron density associated with a covalent bond between oxygen and Fe3+ ions could be observed at the tetrahedral sites. Furthermore, after subtraction of the core electrons sharp peaks were clearly observed, corresponding to d gamma and d epsilon energy states of the d-orbital of the Fe ions. (C) 1998 Elsevier Science B.V. All rights reserved., 1998年01月, 177, 1, 243, 244, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF APPLIED CRYSTALLOGRAPHY, On the estimation of the termination effect in Fourier synthesis in X-ray structure analysis, Y Takahashi; K Ohshima; K Yamamoto; K Yukino; FP Okamura, An accurate structure analysis of a spherical LaB6 single crystal has been performed with the use of short-wavelength X-rays (W K alpha(1)) in order to estimate the termination effect in Fourier synthesis on the electron-density distribution (EDD). It is concluded that the effect on the EDD is negligible if data are taken up to sin theta/lambda = 2.0 Angstrom(-1), because the negative values disappear completely from the map. The values of displacement parameters of the constituent atoms in LaB6 are also discussed., 1998年12月, 31, 917, 921, 研究論文(学術雑誌)
  • 査読あり, 英語, PHILOSOPHICAL MAGAZINE LETTERS, Structure of a new orthorhombic crystalline phase in the Al-Cr-Pd alloy system, Y Matsuo; K Yamamoto; Y Iko, During a study of decagonal quasicrystals and approximant crystals in the Al-Cr-Pd alloy system, a new crystalline phase has been found in an alloy with the composition Al-75(CT, Pd)(25). The crystal structure has been determined by a single-crystal X-ray analysis. This phase has an orthorhombic structure with lattice parameters a = 1.484 nm, b = 1.262 nm and c = 1.272 nm, and the space group is Pnma (No. 62). The atomic model was determined by the least-squares refinement to a final R value of 0.065 for 2418 unique reflections. The atomic arrangement of this phase is considered to be isostructural with Al3Mn and closely related to the structure of the O-phase (proposed by Sun, Yubuta and Hiraga in 1995) and Al-Pd-Mn decagonal quasicrystal. Structural relationships between the Al-75(Cr, Pd)(25) phase, the O-phase, Al3Mn and the Al-Pd-Mn decagonal quasicrystal are discussed., 1997年03月, 75, 3, 137, 142, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, Determination of the chiral structure of CsCuCl3 using anomalous x-ray scattering near the Cs K absorption edge, T Koiso; K Yamamoto; Y Hata; Y Takahashi; E Kita; K Ohshima; FP Okamura, A structural study of CsCuCl3, grown from aqueous solution, was performed using anomalous x-ray scattering near the Cs K absorption edge to determine an absolute configuration of constituent atoms. The sense of the helical structure of the CuCl3 chain was found to be predominantly right-handed through a comparison of observed Bragg Bijvoet ratios with calculated ones. Assuming that CsCuCl3 consists of the two domains (i.e. right- and left-handed helices), we estimate that the volume fraction for the right-handed helix is 0.87 +/- 0.02., 1996年09月, 8, 38, 7059, 7065, 研究論文(学術雑誌)
  • 査読あり, 英語, ACTA CRYSTALLOGRAPHICA SECTION A, MEM Analysis of Electron-Density Distributions for Silicon and Diamond using Short-Wavelength X-rays(WKα11), 山本一樹, Short-wavelength X-rays (W K alpha(1): lambda = 0.209 Angstrom) have been used to collect higher-order reflections for studies of the electron-density distributions of silicon and diamond with high resolution. The sp(3) bonding electron-density distributions of these materials are visible in the total electron-density maps synthesized by the maximum-entropy method (MEM) and also in the difference MEM maps synthesized by Fourier summation of F-mem(h) - F-core(h), where F-mem(h) is the structure factor calculated from the MEM map and F-core(h) is the structure factor calculated from Si-core and C-core models, if very extensive data sets with higher-order reflections are used. These maps are more informative than the conventional difference Fourier map synthesized by Fourier summation of F-obs(h) - F-core(h) using the observed structure factor F-obs(h) instead of F-mem(h). The present maps can be compared with certain band-theory calculations., 1996年07月, 52, 4, 606, 613, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF APPLIED CRYSTALLOGRAPHY, A new technique for making spheres of single crystals, Y Takahashi; K Yamamoto; K Ohshima; K Yukino; FP Okamura, A new technique for making spheres of single crystals is briefly described. It is confirmed that this method is very effective when used to prepare spherical specimens of LaB6, a refractory material that is widely used as a thermo-radiated material., 1996年04月, 29, 1, 206, 207, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, X-RAY-DIFFRACTION STUDY OF LATTICE-PARAMETERS FOR LAYERED COMPOUNDS M(X)TAS(2) (M=TL OR IN), T TAKEDA; S YOKOZEKI; K YAMAMOTO; K OHSHIMA, The composition dependence of lattice parameters for layered compounds M(x)TaS(2) (M = Tl or In, 0 < x < 0.6) has been determined by an x-ray diffraction method, in order to discuss the structural characteristics. Stage-2 and stage-1 phases for both compounds exist. A drastic change in the c-axis layer spacing was found for stage-1 Tl0.465TaS2, although there was no such anomaly in the composition dependence of the c-axis lattice parameter for InxTaS2., 1995年06月, 7, 24, 4625, 4628, 研究論文(学術雑誌)
  • 査読あり, 英語, SOLID STATE IONICS, X-RAY STUDY OF THE CATION DISTRIBUTION IN CU2SE, CU1.8SE AND CU1.8S - ANALYSIS BY THE MAXIMUM-ENTROPY METHOD, K YAMAMOTO; S KASHIDA, The structures of fast ion conductors Cu2Se, Cu1.8Se and Cu1.8S have been studied with the use of single crystal X-ray diffraction data. The compounds have cubic antifluorite structures, copper ions and distributed to the tetrahedral, trigonal and octahedral interstitials of the chalcogen atoms. In the refinement of the structures, the maximum entropy method (MEM) is used to construct the density map of the copper ions. The distribution of the copper ions is studied as a function of temperature. The diffusion path of the mobile copper ions is also discussed. The present method, MEM is found to have several advantages over the previous methods, such as the split atom, the anharmonic and the excluded volume models., 1991年11月, 48, 3-4, 241, 248, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF SOLID STATE CHEMISTRY, X-RAY STUDY OF THE AVERAGE STRUCTURES OF CU2SE AND CU1.8S IN THE ROOM-TEMPERATURE AND THE HIGH-TEMPERATURE PHASES, K YAMAMOTO; S KASHIDA, 1991年07月, 93, 1, 202, 211, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, AN X-RAY STUDY OF THE INCOMMENSURATE STRUCTURE IN DIGENITE (CU1.8S), S KASHIDA; K YAMAMOTO, The structure of a non-stoichiometric copper compound Cu1.8S (digenite) has been studied by x-ray diffraction. Although digenite has a cubic anti-fluorite structure, satellite reflections were seen along the <111>c axis. Single-crystal x-ray diffraction data, including first- and second-order satellites, were collected using a four-circle diffractometer. A rhombohedral twinning model was used to determine the modulation densities of the copper ions. The final R-factor is about 10% including the main and satellite reflections. The present analysis shows that the crystal is composed of domain-like structures: in each domain, the dimensions of the regular lattice, formed from copper ions, are slightly larger than those of the basic sulphur lattice. The origin of this domain-like structure, based on the Frenkel-Kontorova model, is attributed to the non-stoichiometry and apparently smaller cation-anion interaction., 1991年08月, 3, 34, 6559, 6570, 研究論文(学術雑誌)
  • 査読あり, 英語, JOURNAL OF SOLID STATE CHEMISTRY, STRUCTURAL PHASE-TRANSITION IN KHCO3, S KASHIDA; K YAMAMOTO, 1990年06月, 86, 2, 180, 187, 研究論文(学術雑誌)

MISC

  • 査読無し, 英語, MATERIALS TRANSACTIONS, JAPAN INST METALS, X-ray Study of Phason Strains in an AlCuFeMn Decagonal Phase, Wang Yang; Tomoyo Ando; Kazuki Yamamoto, The peak profiles, shifts, and splittings of Bragg reflections, which are inherent in the phason strain of a quasicrystal, are carefully examined using a precise powder X-ray diffraction method for a wide range of different AlCuFeMn alloys and annealing temperatures. Based on the peak-shift dependences of the Bragg reflections on the phason momentum Q(perpendicular to), two kinds of new approximant phases are identifled. These phases have linear phason strains theta(1) = tau(-6) and theta(2) = tau(-5), and theta(1) = tau(-10) and theta(2) =tau(-5), corresponding to lattice spacings a=3.814 nm and b = 2.005 nm, and a = 9.985 nm and b = 2.005 nm in the quasiperiodic plane of the orthorhombic system, respectively., 2017年, 58, 6, 847, 851, 書評論文,書評,文献紹介等
  • 査読無し, 英語, MATERIALS TRANSACTIONS, JAPAN INST METALS, X-ray Study of Phason Strains in an AlCuFeMn Decagonal Phase, Wang Yang; Tomoyo Ando; Kazuki Yamamoto, The peak profiles, shifts, and splittings of Bragg reflections, which are inherent in the phason strain of a quasicrystal, are carefully examined using a precise powder X-ray diffraction method for a wide range of different AlCuFeMn alloys and annealing temperatures. Based on the peak-shift dependences of the Bragg reflections on the phason momentum Q(perpendicular to), two kinds of new approximant phases are identifled. These phases have linear phason strains theta(1) = tau(-6) and theta(2) = tau(-5), and theta(1) = tau(-10) and theta(2) =tau(-5), corresponding to lattice spacings a=3.814 nm and b = 2.005 nm, and a = 9.985 nm and b = 2.005 nm in the quasiperiodic plane of the orthorhombic system, respectively., 2017年, 58, 6, 847, 851, 書評論文,書評,文献紹介等
  • 査読無し, 英語, SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, NATL INST MATERIALS SCIENCE, X-ray structural study of the layered compounds CoxNbS2, T Ueno; K Yamamoto; H Matsukura; T Kusawake; K Ohshima, X-ray intensity measurements have been performed on the structure of the layered compound CoxNbS2 single crystals (x <= 0.5) at room temperature. The c-axis lattice parameter changes discontinuously at around x=0.2 and remains constant with further increase of the Co content. For the lower content of Co atoms (x < 0.2), no diffuse maxima appeared on the (hk0) and (hk1) reciprocal lattice planes. At x=0.23, the diffuse maxima are clearly seen at 4/3, 4/3, 1 and 5/3, 5/3, 1 reciprocal lattice points. At -Y=0.32, sharp intensity maxima appear at 4/3, 4/3, 0 and 5/3, 5/3, 0 in addition to at 4/3, 4/3, 1 and 5/3, 5/3, 1. It is understood that root 3 X root(3R0 degrees) ordered structure exists at the stoichiometric composition of x=1/3. At further increasing the Co content, the intensity at 4/3, 4/3, 0 and 5/3, 5/3, 0 is weakening and disappears above x = 0.4. The structural model based on the space group P6(3)22 (No. 182) for CoxNbS2 (x > 0.4) is discussed with considering both the position of the Co atoms and their occupation rate. (c) 2005 Elsevier Ltd. All rights reserved., 2005年09月, 6, 6, 684, 688
  • 査読無し, 英語, SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, NATL INST MATERIALS SCIENCE, X-ray structural study of the layered compounds CoxNbS2, T Ueno; K Yamamoto; H Matsukura; T Kusawake; K Ohshima, X-ray intensity measurements have been performed on the structure of the layered compound CoxNbS2 single crystals (x <= 0.5) at room temperature. The c-axis lattice parameter changes discontinuously at around x=0.2 and remains constant with further increase of the Co content. For the lower content of Co atoms (x < 0.2), no diffuse maxima appeared on the (hk0) and (hk1) reciprocal lattice planes. At x=0.23, the diffuse maxima are clearly seen at 4/3, 4/3, 1 and 5/3, 5/3, 1 reciprocal lattice points. At -Y=0.32, sharp intensity maxima appear at 4/3, 4/3, 0 and 5/3, 5/3, 0 in addition to at 4/3, 4/3, 1 and 5/3, 5/3, 1. It is understood that root 3 X root(3R0 degrees) ordered structure exists at the stoichiometric composition of x=1/3. At further increasing the Co content, the intensity at 4/3, 4/3, 0 and 5/3, 5/3, 0 is weakening and disappears above x = 0.4. The structural model based on the space group P6(3)22 (No. 182) for CoxNbS2 (x > 0.4) is discussed with considering both the position of the Co atoms and their occupation rate. (c) 2005 Elsevier Ltd. All rights reserved., 2005年09月, 6, 6, 684, 688
  • 査読無し, 英語, MATERIALS TRANSACTIONS, JAPAN INST METALS, Synchrotron X-ray studies of phason and phonon strains in a Co-rich Al-Ni-Co decagonal quasicrystal, K Yamamoto; W Yang; Y Nishimura; N Ikeda; Y Matsuo, Peak broadening and peak shifts of Bragg reflections were studied with the synchrotron single-crystal X-ray diffraction method for an Al72.7Ni8.5Co18.8 decagonal quasicrystal classified as the 5f state. From the Q(perpendicular to) and Q(parallel to) dependences of the full width of half maximum (FWHM) of the Bragg reflections along the longitudinal direction, the coexistence of random phason strains with phonon strains was observed. High-resolution synchrotron X-ray measurements Could present quantitative estimations of these strains. The value of the random phason strain component is 0.0054 similar to tau(-11). The asymmetrical broadening due to the phonon strain shows that the single crystal may be constructed with two kinds of grains that have A(5D) values of 0.6273 and 0.6265 nm., 2004年04月, 45, 4, 1255, 1260
  • 査読無し, 英語, MATERIALS TRANSACTIONS, JAPAN INST METALS, Synchrotron X-ray studies of phason and phonon strains in a Co-rich Al-Ni-Co decagonal quasicrystal, K Yamamoto; W Yang; Y Nishimura; N Ikeda; Y Matsuo, Peak broadening and peak shifts of Bragg reflections were studied with the synchrotron single-crystal X-ray diffraction method for an Al72.7Ni8.5Co18.8 decagonal quasicrystal classified as the 5f state. From the Q(perpendicular to) and Q(parallel to) dependences of the full width of half maximum (FWHM) of the Bragg reflections along the longitudinal direction, the coexistence of random phason strains with phonon strains was observed. High-resolution synchrotron X-ray measurements Could present quantitative estimations of these strains. The value of the random phason strain component is 0.0054 similar to tau(-11). The asymmetrical broadening due to the phonon strain shows that the single crystal may be constructed with two kinds of grains that have A(5D) values of 0.6273 and 0.6265 nm., 2004年04月, 45, 4, 1255, 1260
  • 査読無し, 英語, JOURNAL OF ALLOYS AND COMPOUNDS, ELSEVIER SCIENCE SA, The successive phase transformation in a Co-rich Al-Ni-Co decagonal phase, K Yamamoto; W Yang; Y Nishimura; Y Matsuo, Peak broadening and the peak positions of Bragg reflections were studied with the high-resolution X-ray diffraction method for decagonal Al72.7Ni8.5Co18.8 quasicrystals. From the Q(perpendicular to) dependences of the full-width at half-maximum (FWHM) of the Bragg reflections and the peak shifts from ideal Bragg peak positions along the longitudinal direction, these decagonal quasicrystals were classified into three groups with different phason strains. These three group, were identified as the random phason strain, the one-dimensional linear phason strain and the two-dimensional linear phason strain, respectively. This means that the Al72.7Ni8.5Co18.8 decagonal phase undergoes a successive phase transformation from a decagonal quasicrystal through a one-dimensional quasicrystal to an approximant crystal. (C) 2002 Elsevier Science B.V. All rights reserved., 2002年08月, 342, 1-2, 237, 240
  • 査読無し, 英語, JOURNAL OF ALLOYS AND COMPOUNDS, ELSEVIER SCIENCE SA, The successive phase transformation in a Co-rich Al-Ni-Co decagonal phase, K Yamamoto; W Yang; Y Nishimura; Y Matsuo, Peak broadening and the peak positions of Bragg reflections were studied with the high-resolution X-ray diffraction method for decagonal Al72.7Ni8.5Co18.8 quasicrystals. From the Q(perpendicular to) dependences of the full-width at half-maximum (FWHM) of the Bragg reflections and the peak shifts from ideal Bragg peak positions along the longitudinal direction, these decagonal quasicrystals were classified into three groups with different phason strains. These three group, were identified as the random phason strain, the one-dimensional linear phason strain and the two-dimensional linear phason strain, respectively. This means that the Al72.7Ni8.5Co18.8 decagonal phase undergoes a successive phase transformation from a decagonal quasicrystal through a one-dimensional quasicrystal to an approximant crystal. (C) 2002 Elsevier Science B.V. All rights reserved., 2002年08月, 342, 1-2, 237, 240
  • 査読無し, 英語, Materials Transactions, Japan Institute of Metals (JIM), Growth condition and x-ray analysis of single Al64Cu23Fe13 icosahedral quasicrystal by the Czochralski method, Yoshihiko Yokoyama; Yoshie Matsuo; Kazuki Yamamoto; Kenji Hiraga, Growth conditions for the preparation of a single Al64Cu23Fe13 icosahedral (I-) quasicrystal with excellent quasicrystallinity were examined using the Czochralski method. The appreciation of the quasicrystallinity of the grown single quasicrystal was performed by X-ray structural analysis. The full widths at half-maximum (FWHM) of the Bragg reflections along 2-, 3- and 5-fold symmetry directions have no Q∥ and Q⊥ dependence. Where the Q∥ and Q⊥ mean the phason momentum and real scattering vector. Furthermore, peak shifts from ideal Bragg positions were not observed. These means that the grown Al64Cu23Fe13 quasicrystal by the Czochralski method has perfect I-phase structure., 2002年, 43, 4, 762, 765
  • 査読無し, 英語, Materials Transactions, Japan Institute of Metals (JIM), Growth condition and x-ray analysis of single Al64Cu23Fe13 icosahedral quasicrystal by the Czochralski method, Yoshihiko Yokoyama; Yoshie Matsuo; Kazuki Yamamoto; Kenji Hiraga, Growth conditions for the preparation of a single Al64Cu23Fe13 icosahedral (I-) quasicrystal with excellent quasicrystallinity were examined using the Czochralski method. The appreciation of the quasicrystallinity of the grown single quasicrystal was performed by X-ray structural analysis. The full widths at half-maximum (FWHM) of the Bragg reflections along 2-, 3- and 5-fold symmetry directions have no Q∥ and Q⊥ dependence. Where the Q∥ and Q⊥ mean the phason momentum and real scattering vector. Furthermore, peak shifts from ideal Bragg positions were not observed. These means that the grown Al64Cu23Fe13 quasicrystal by the Czochralski method has perfect I-phase structure., 2002年, 43, 4, 762, 765
  • 査読無し, 英語, PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES, TAYLOR & FRANCIS LTD, X-ray diffraction study of a phason strain in an Al-Cu-Fe icosahedral quasicrystal, M Jono; Y Matsuo; K Yamamoto; Y Ishii, Detailed examinations of the peak profiles and the positions of the Bragg peaks are carried out with the X-ray diffractometer for single-grain samples of the Al-Cu-Fe icosahedral quasicrystal. Notable peak shifts from the ideal positions with linear Q(perpendicular to) dependence are observed along the fivefold directions. This means that the sample contains linear phason strain. The amplitude of the linear phason strain is estimated as -0.0543, which is close to a theoretical value for the phason-strain-inducing transformation from the icosahedral phase to the pentagonal phase (P2 phase), -1/tau (6). The two-dimensional intensity distributions around the Bragg peaks on the twofold, threefold and fivefold axes are interpreted as consequences of the phason-strain-inducing pentagonal deformation., 2001年11月, 81, 11, 2577, 2590
  • 査読無し, 英語, PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES, TAYLOR & FRANCIS LTD, X-ray diffraction study of a phason strain in an Al-Cu-Fe icosahedral quasicrystal, M Jono; Y Matsuo; K Yamamoto; Y Ishii, Detailed examinations of the peak profiles and the positions of the Bragg peaks are carried out with the X-ray diffractometer for single-grain samples of the Al-Cu-Fe icosahedral quasicrystal. Notable peak shifts from the ideal positions with linear Q(perpendicular to) dependence are observed along the fivefold directions. This means that the sample contains linear phason strain. The amplitude of the linear phason strain is estimated as -0.0543, which is close to a theoretical value for the phason-strain-inducing transformation from the icosahedral phase to the pentagonal phase (P2 phase), -1/tau (6). The two-dimensional intensity distributions around the Bragg peaks on the twofold, threefold and fivefold axes are interpreted as consequences of the phason-strain-inducing pentagonal deformation., 2001年11月, 81, 11, 2577, 2590
  • 査読無し, 英語, MATERIALS TRANSACTIONS, JAPAN INST METALS, Relationship between phason strain and approximant crystal structure in Co-rich Al-Ni-Co decagonal phase, Y Matsuo; Y Nishimura; K Yamamoto; Y Ishii, Peak broadening and the peak positions of the Bragg reflections were studied with the high-resolution X-ray diffraction method for the decagonal Al72.7Ni8.5Co18.8 quasicrystal. The full-widths at half-maximum (FWHM) of the Bragg reflections along the longitudinal direction (L), which is perpendicular to the periodic axis, have no Q(parallel to) or Q(perpendicular to) dependences. On the other hand, notable peak shifts from ideal Bragg peak positions with linear Q, dependence were observed. This means that the Al72.7Ni8.5Co18.8 decagonal phase has linear phason strains. According to the absolute values of the linear phason strains, the transformation from the decagonal phase to an approximant crystal is discussed., 2001年09月, 42, 9, 2008, 2012
  • 査読無し, 英語, MATERIALS TRANSACTIONS, JAPAN INST METALS, Relationship between phason strain and approximant crystal structure in Co-rich Al-Ni-Co decagonal phase, Y Matsuo; Y Nishimura; K Yamamoto; Y Ishii, Peak broadening and the peak positions of the Bragg reflections were studied with the high-resolution X-ray diffraction method for the decagonal Al72.7Ni8.5Co18.8 quasicrystal. The full-widths at half-maximum (FWHM) of the Bragg reflections along the longitudinal direction (L), which is perpendicular to the periodic axis, have no Q(parallel to) or Q(perpendicular to) dependences. On the other hand, notable peak shifts from ideal Bragg peak positions with linear Q, dependence were observed. This means that the Al72.7Ni8.5Co18.8 decagonal phase has linear phason strains. According to the absolute values of the linear phason strains, the transformation from the decagonal phase to an approximant crystal is discussed., 2001年09月, 42, 9, 2008, 2012
  • 査読無し, その他, Journal of Physics : Condensed Matter, X-ray study of the electron density distribution in Al6Mn, 山本 一樹; K Yamamoto; Y Matsuo, 2000年, 12, 2359, 2365
  • 査読無し, その他, Journal of Physics : Condensed Matter, X-ray study of the electron density distribution in Al6Mn, YAMAMOTO Kazuki; K Yamamoto; Y Matsuo, 2000年, 12, 2359, 2365
  • 査読無し, 英語, MATERIALS TRANSACTIONS JIM, JAPAN INST METALS, X-ray diffraction study of the decagonal Al70Ni10Co20, Y Matsuo; N Sugiyama; K Yamamoto, A decagonal Al70Ni10Co20 single quasicrystal was studied with high-resolution X-ray diffraction. Full-widths at half-maximum (FWHM) of Bragg reflections along the longitudinal direction (L) monotonically increase with increasing of Q(perpendicular to). This result suggests that the Al70Ni10Co20 decagonal phase has random phason strain. On the other hand, FWHM for both transverse directions T1 and T2, which are perpendicular to the L-direction in an aperiodic plane (T1) and along a periodic direction (T2), have linear Q(parallel to) dependence. So the single crystal has some distortion of mosaics. Notable peak shifts from ideal Bragg peak positions were not observed., 1999年02月, 40, 2, 137, 140
  • 査読無し, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, IOP PUBLISHING LTD, X-ray study of the electron density distributions for hexagonal Al5Co2 and Al10Mn3, K Yamamoto; M Jono; Y Matsuo, The electron density distributions of Al5Co2 and Al10Mn3, which include icosahedral clusters, have been studied by a single-crystal x-ray diffraction method. The maximum-entropy method (MEM) is used to construct the electron density distribution (EDD). In the EDD maps, strongly covalent bonds between Al atoms and transition metal (TM) atoms are visible. As regards the chemical bonding, Al10Mn3 has an icosahedral bonding environment, whereas Al5Co2 does not. The number of electrons belonging to each atom and the charge transfer from Al atoms to TM atoms have been derived from the EDD maps. The negative valences were estimated to be -1.25 and -1.26 for Co atoms and -1.00 for a Mn atom. These negative valences can be understood to be the charge transfer due to the covalent bond with strongly ionic character. These results were compared with pair-potential calculations and band-structure calculations., 1999年02月, 11, 4, 1015, 1026
  • 査読無し, 英語, MATERIALS TRANSACTIONS JIM, JAPAN INST METALS, X-ray diffraction study of the decagonal Al70Ni10Co20, Y Matsuo; N Sugiyama; K Yamamoto, A decagonal Al70Ni10Co20 single quasicrystal was studied with high-resolution X-ray diffraction. Full-widths at half-maximum (FWHM) of Bragg reflections along the longitudinal direction (L) monotonically increase with increasing of Q(perpendicular to). This result suggests that the Al70Ni10Co20 decagonal phase has random phason strain. On the other hand, FWHM for both transverse directions T1 and T2, which are perpendicular to the L-direction in an aperiodic plane (T1) and along a periodic direction (T2), have linear Q(parallel to) dependence. So the single crystal has some distortion of mosaics. Notable peak shifts from ideal Bragg peak positions were not observed., 1999年02月, 40, 2, 137, 140
  • 査読無し, その他, Journal of Physics : Condensed Matter, X-ray Study of the Electron Density Distribution for Hexagonal Al5Co2 and Al10Mn3, YAMAMOTO Kazuki; K Yamamoto; M.Jono; Y Matsuo, 1999年, 11, 1015, 1026
  • 査読無し, 英語, JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, JAPAN J APPLIED PHYSICS, X-ray fluorescence analysis of rare-earth atoms in materials by use of ultrashort wavelength X-rays, Y Takahashi; K Yamamoto; K Ohshima; K Yukino; FP Okamura, A new technique of X-ray fluorescence analysis using ultrashort-wavelength X-rays was tested to obtain the K-series of spectra for rare-earth elements in two different kinds of materials, i.e. powder samples of rare-earth oxides and single crystals of rare-earth hexaborides. This technique utilizes a solid-state detector and multichannel pulse-height analyzer, and satisfies the requirements for quantitative identification in samples containing heavy elements. This technique was applied to determine the composition of the mixed compound La1-xCexB6 (z = 0.25, 0.50 and 0.75). There is good agreement, within the limits of experimental error, between the values thus obtained and the nominal values., 1998年05月, 37, 5A, L556, L558
  • 査読無し, その他, Journal of Physics : Condensed Matter, Investigation of phason strain in decagonal Al-Pd-Mn single crystals by means of X-ray diffraction, 山本 一樹; Y Matsuo; K Yamamoto; Y Ishii, 1998年, 10, 5, 983
  • 査読無し, その他, Proceedings of the 6th International Conference on Quasicrystals, X-ray Diffuse Scattering in the Al-Pd-Mn Decagonal Quasicrystal, 山本 一樹; K Yamamoto; Y Matsuo; M Ota, 1998年, 403
  • 査読無し, 英語, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, An observation of localized 3d electron density distribution of Fe3O4, Y Kino; FP Okamura; K Yamamoto; K Siratori, Measurement of X-ray diffraction data using WK alpha (lambda = 0.20889 Angstrom) radiation was carried out on Fe3O4 at room temperature. Data were analyzed using the maximum entropy method (MEM). The electron density distribution of the (1 0 0) and (1 1 0) planes of Fe3O4 are examined in detail. Electron density associated with a covalent bond between oxygen and Fe3+ ions could be observed at the tetrahedral sites. Furthermore, after subtraction of the core electrons sharp peaks were clearly observed, corresponding to d gamma and d epsilon energy states of the d-orbital of the Fe ions. (C) 1998 Elsevier Science B.V. All rights reserved., 1998年01月, 177, 1, 243, 244
  • 査読無し, 英語, JOURNAL OF APPLIED CRYSTALLOGRAPHY, MUNKSGAARD INT PUBL LTD, On the estimation of the termination effect in Fourier synthesis in X-ray structure analysis, Y Takahashi; K Ohshima; K Yamamoto; K Yukino; FP Okamura, An accurate structure analysis of a spherical LaB6 single crystal has been performed with the use of short-wavelength X-rays (W K alpha(1)) in order to estimate the termination effect in Fourier synthesis on the electron-density distribution (EDD). It is concluded that the effect on the EDD is negligible if data are taken up to sin theta/lambda = 2.0 Angstrom(-1), because the negative values disappear completely from the map. The values of displacement parameters of the constituent atoms in LaB6 are also discussed., 1998年12月, 31, 917, 921
  • 査読無し, 英語, JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, JAPAN J APPLIED PHYSICS, X-ray fluorescence analysis of rare-earth atoms in materials by use of ultrashort wavelength X-rays, Y Takahashi; K Yamamoto; K Ohshima; K Yukino; FP Okamura, A new technique of X-ray fluorescence analysis using ultrashort-wavelength X-rays was tested to obtain the K-series of spectra for rare-earth elements in two different kinds of materials, i.e. powder samples of rare-earth oxides and single crystals of rare-earth hexaborides. This technique utilizes a solid-state detector and multichannel pulse-height analyzer, and satisfies the requirements for quantitative identification in samples containing heavy elements. This technique was applied to determine the composition of the mixed compound La1-xCexB6 (z = 0.25, 0.50 and 0.75). There is good agreement, within the limits of experimental error, between the values thus obtained and the nominal values., 1998年05月, 37, 5A, L556, L558
  • 査読無し, その他, Journal of Physics : Condensed Matter, Investigation of phason strain in decagonal Al-Pd-Mn single crystals by means of X-ray diffraction, YAMAMOTO Kazuki; Y Matsuo; K Yamamoto; Y Ishii, 1998年, 10, 5, 983
  • 査読無し, その他, Proceedings of the 6th International Conference on Quasicrystals, X-ray Diffuse Scattering in the Al-Pd-Mn Decagonal Quasicrystal, YAMAMOTO Kazuki; K Yamamoto; Y Matsuo; M Ota, 1998年, 403
  • 査読無し, 英語, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, ELSEVIER SCIENCE BV, An observation of localized 3d electron density distribution of Fe3O4, Y Kino; FP Okamura; K Yamamoto; K Siratori, Measurement of X-ray diffraction data using WK alpha (lambda = 0.20889 Angstrom) radiation was carried out on Fe3O4 at room temperature. Data were analyzed using the maximum entropy method (MEM). The electron density distribution of the (1 0 0) and (1 1 0) planes of Fe3O4 are examined in detail. Electron density associated with a covalent bond between oxygen and Fe3+ ions could be observed at the tetrahedral sites. Furthermore, after subtraction of the core electrons sharp peaks were clearly observed, corresponding to d gamma and d epsilon energy states of the d-orbital of the Fe ions. (C) 1998 Elsevier Science B.V. All rights reserved., 1998年01月, 177, 1, 243, 244
  • 査読無し, 英語, JOURNAL OF APPLIED CRYSTALLOGRAPHY, MUNKSGAARD INT PUBL LTD, On the estimation of the termination effect in Fourier synthesis in X-ray structure analysis, Y Takahashi; K Ohshima; K Yamamoto; K Yukino; FP Okamura, An accurate structure analysis of a spherical LaB6 single crystal has been performed with the use of short-wavelength X-rays (W K alpha(1)) in order to estimate the termination effect in Fourier synthesis on the electron-density distribution (EDD). It is concluded that the effect on the EDD is negligible if data are taken up to sin theta/lambda = 2.0 Angstrom(-1), because the negative values disappear completely from the map. The values of displacement parameters of the constituent atoms in LaB6 are also discussed., 1998年12月, 31, 917, 921
  • 査読無し, 英語, PHILOSOPHICAL MAGAZINE LETTERS, TAYLOR & FRANCIS LTD, Structure of a new orthorhombic crystalline phase in the Al-Cr-Pd alloy system, Y Matsuo; K Yamamoto; Y Iko, During a study of decagonal quasicrystals and approximant crystals in the Al-Cr-Pd alloy system, a new crystalline phase has been found in an alloy with the composition Al-75(CT, Pd)(25). The crystal structure has been determined by a single-crystal X-ray analysis. This phase has an orthorhombic structure with lattice parameters a = 1.484 nm, b = 1.262 nm and c = 1.272 nm, and the space group is Pnma (No. 62). The atomic model was determined by the least-squares refinement to a final R value of 0.065 for 2418 unique reflections. The atomic arrangement of this phase is considered to be isostructural with Al3Mn and closely related to the structure of the O-phase (proposed by Sun, Yubuta and Hiraga in 1995) and Al-Pd-Mn decagonal quasicrystal. Structural relationships between the Al-75(Cr, Pd)(25) phase, the O-phase, Al3Mn and the Al-Pd-Mn decagonal quasicrystal are discussed., 1997年03月, 75, 3, 137, 142
  • 査読無し, 英語, PHILOSOPHICAL MAGAZINE LETTERS, TAYLOR & FRANCIS LTD, Structure of a new orthorhombic crystalline phase in the Al-Cr-Pd alloy system, Y Matsuo; K Yamamoto; Y Iko, During a study of decagonal quasicrystals and approximant crystals in the Al-Cr-Pd alloy system, a new crystalline phase has been found in an alloy with the composition Al-75(CT, Pd)(25). The crystal structure has been determined by a single-crystal X-ray analysis. This phase has an orthorhombic structure with lattice parameters a = 1.484 nm, b = 1.262 nm and c = 1.272 nm, and the space group is Pnma (No. 62). The atomic model was determined by the least-squares refinement to a final R value of 0.065 for 2418 unique reflections. The atomic arrangement of this phase is considered to be isostructural with Al3Mn and closely related to the structure of the O-phase (proposed by Sun, Yubuta and Hiraga in 1995) and Al-Pd-Mn decagonal quasicrystal. Structural relationships between the Al-75(Cr, Pd)(25) phase, the O-phase, Al3Mn and the Al-Pd-Mn decagonal quasicrystal are discussed., 1997年03月, 75, 3, 137, 142
  • 査読無し, 英語, Journal of Physics Condensed Matter, Determination of the chiral structure of CsCuCl3 using anomalous x-ray scattering near the Cs K absorption edge, T. Koiso; K. Yamamoto; Y. Hata; Y. Takahashi; E. Kita; K. Ohshima; F. P. Okamura, A structural study of CsCuCl3, grown from aqueous solution, was performed using anomalous x-ray scattering near the Cs K absorption edge to determine an absolute configuration of constituent atoms. The sense of the helical structure of the CuCl3 chain was found to be predominantly right-handed through a comparison of observed Bragg Bijvoet ratios with calculated ones. Assuming that CsCuCl3 consists of the two domains (i.e. right- and left-handed helices), we estimate that the volume fraction for the right-handed helix is 0.87 ± 0.02., 1996年09月16日, 8, 38, 7059, 7065
  • 査読無し, 英語, Journal of Physics Condensed Matter, Determination of the chiral structure of CsCuCl3 using anomalous x-ray scattering near the Cs K absorption edge, T. Koiso; K. Yamamoto; Y. Hata; Y. Takahashi; E. Kita; K. Ohshima; F. P. Okamura, A structural study of CsCuCl3, grown from aqueous solution, was performed using anomalous x-ray scattering near the Cs K absorption edge to determine an absolute configuration of constituent atoms. The sense of the helical structure of the CuCl3 chain was found to be predominantly right-handed through a comparison of observed Bragg Bijvoet ratios with calculated ones. Assuming that CsCuCl3 consists of the two domains (i.e. right- and left-handed helices), we estimate that the volume fraction for the right-handed helix is 0.87 ± 0.02., 1996年09月16日, 8, 38, 7059, 7065
  • 査読無し, 英語, JOURNAL OF APPLIED CRYSTALLOGRAPHY, MUNKSGAARD INT PUBL LTD, A new technique for making spheres of single crystals, Y Takahashi; K Yamamoto; K Ohshima; K Yukino; FP Okamura, A new technique for making spheres of single crystals is briefly described. It is confirmed that this method is very effective when used to prepare spherical specimens of LaB6, a refractory material that is widely used as a thermo-radiated material., 1996年04月, 29, 1, 206, 207
  • 査読無し, 英語, JOURNAL OF APPLIED CRYSTALLOGRAPHY, MUNKSGAARD INT PUBL LTD, A new technique for making spheres of single crystals, Y Takahashi; K Yamamoto; K Ohshima; K Yukino; FP Okamura, A new technique for making spheres of single crystals is briefly described. It is confirmed that this method is very effective when used to prepare spherical specimens of LaB6, a refractory material that is widely used as a thermo-radiated material., 1996年04月, 29, 1, 206, 207
  • 査読無し, その他, Acta Crystallographica A, MEM Analysis of Electron-Density Distributions for Silicon and Diamond using Short-Wavelength X-rays(WKα11), 山本 一樹; K. Yamamoto; Y. Takahashi; K. Ohshima; F. P. Okamura; K. Yukino, 1996年, 52, 4, 606
  • 査読無し, その他, Acta Crystallographica A, MEM Analysis of Electron-Density Distributions for Silicon and Diamond using Short-Wavelength X-rays(WKα11), YAMAMOTO Kazuki; K. Yamamoto; Y. Takahashi; K. Ohshima; F. P. Okamura; K. Yukino, 1996年, 52, 4, 606
  • 査読無し, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, IOP PUBLISHING LTD, X-RAY-DIFFRACTION STUDY OF LATTICE-PARAMETERS FOR LAYERED COMPOUNDS M(X)TAS(2) (M=TL OR IN), T TAKEDA; S YOKOZEKI; K YAMAMOTO; K OHSHIMA, The composition dependence of lattice parameters for layered compounds M(x)TaS(2) (M = Tl or In, 0 < x < 0.6) has been determined by an x-ray diffraction method, in order to discuss the structural characteristics. Stage-2 and stage-1 phases for both compounds exist. A drastic change in the c-axis layer spacing was found for stage-1 Tl0.465TaS2, although there was no such anomaly in the composition dependence of the c-axis lattice parameter for InxTaS2., 1995年06月, 7, 24, 4625, 4628
  • 査読無し, 英語, JOURNAL OF PHYSICS-CONDENSED MATTER, IOP PUBLISHING LTD, X-RAY-DIFFRACTION STUDY OF LATTICE-PARAMETERS FOR LAYERED COMPOUNDS M(X)TAS(2) (M=TL OR IN), T TAKEDA; S YOKOZEKI; K YAMAMOTO; K OHSHIMA, The composition dependence of lattice parameters for layered compounds M(x)TaS(2) (M = Tl or In, 0 < x < 0.6) has been determined by an x-ray diffraction method, in order to discuss the structural characteristics. Stage-2 and stage-1 phases for both compounds exist. A drastic change in the c-axis layer spacing was found for stage-1 Tl0.465TaS2, although there was no such anomaly in the composition dependence of the c-axis lattice parameter for InxTaS2., 1995年06月, 7, 24, 4625, 4628
  • 査読無し, その他, Journal of Solid State Chemistry, X-ray Study of Average Structure of Cu2Se and Cu1.8S in the Room Temperature and the High Temperature Phases, 山本 一樹; K.Yamamoto; S.Kashida, 1991年, 93, 1, 202
  • 査読無し, その他, Journal of Physics Condensed Matter, An X-ray Study of the Incommensurate in Digenite(Cu1.8S), 山本 一樹; S.Kashida; K.Yamamoto, 1991年, 3, 34, 6559
  • 査読無し, 英語, SOLID STATE IONICS, ELSEVIER SCIENCE BV, X-RAY STUDY OF THE CATION DISTRIBUTION IN CU2SE, CU1.8SE AND CU1.8S - ANALYSIS BY THE MAXIMUM-ENTROPY METHOD, K YAMAMOTO; S KASHIDA, The structures of fast ion conductors Cu2Se, Cu1.8Se and Cu1.8S have been studied with the use of single crystal X-ray diffraction data. The compounds have cubic antifluorite structures, copper ions and distributed to the tetrahedral, trigonal and octahedral interstitials of the chalcogen atoms. In the refinement of the structures, the maximum entropy method (MEM) is used to construct the density map of the copper ions. The distribution of the copper ions is studied as a function of temperature. The diffusion path of the mobile copper ions is also discussed. The present method, MEM is found to have several advantages over the previous methods, such as the split atom, the anharmonic and the excluded volume models., 1991年11月, 48, 3-4, 241, 248
  • 査読無し, その他, Journal of Solid State Chemistry, X-ray Study of Average Structure of Cu2Se and Cu1.8S in the Room Temperature and the High Temperature Phases, YAMAMOTO Kazuki; K.Yamamoto; S.Kashida, 1991年, 93, 1, 202
  • 査読無し, その他, Journal of Physics Condensed Matter, An X-ray Study of the Incommensurate in Digenite(Cu1.8S), YAMAMOTO Kazuki; S.Kashida; K.Yamamoto, 1991年, 3, 34, 6559
  • 査読無し, その他, Solid State Ionics, X-ray Study of Cation distribution in Cu2Se1 Cu1,8Se and Cu1.8S : Analysis by the Maximum Entropy Method, YAMAMOTO Kazuki, 1991年, 48, 3-4, 24
  • 査読無し, その他, Journal of Solid State Chemistry, Strucral Phase Transition in KHCO3, 山本 一樹; S.Kashida; K.Yamamoto, 1990年, 86, 2, 180
  • 査読無し, その他, Journal of Solid State Chemistry, Strucral Phase Transition in KHCO3, YAMAMOTO Kazuki; S.Kashida; K.Yamamoto, 1990年, 86, 2, 180
  • 日本語, 春の分科会講演予稿集, 一般社団法人日本物理学会, 26p-W-1 Cu_<1.8>SとCu_2Seのマキシマムエントロピー法による構造解析, 山本 一樹; 樫田 昭次, 1991年03月11日, 1991, 2, 265, 265
  • 日本語, 日本物理学会講演概要集. 年会, 一般社団法人日本物理学会, 2p-R-2 超短波長X線による結晶の電子密度分布, 山本 一樹, 1996年03月15日, 51, 2, 107, 108

書籍等出版物

  • Phason Strain in Al70Ni10Co20 Decagonal Quasicrystal 「共著」, Materials Research Society Symposium Proceeding ; Quasicrystal, 山本一樹, 1999年, 553巻183-187頁, 英語, 査読無し, その他

共同研究・競争的資金等の研究課題

  • 2010年, 層間化合物の構造研究, 0, 0, 0, 競争的資金
  • 1996年, 準結晶の構造に関するX線による研究, 0, 0, 0, 競争的資金
  • 1996年, X-ray Study of Structure for Quasicrystals, 0, 0, 0, 競争的資金
  • 1991年, 結晶内電子密度分布のX線による研究, 0, 0, 0, 競争的資金
  • 1991年, X-ray Study of Electron Density Distributions in Crystals., 0, 0, 0, 競争的資金

Ⅲ.社会連携活動実績

2. 学外非常勤講師等

  • 京都医療技術センター付属看護助産学校, 生活と物理
  • 京都医療技術センター付属看護助産学校, 生活と物理


Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.