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Journal Articles

Inter atomic force constants of $$beta$$-PbF$$_{2}$$ from diffuse neutron scattering measurement

Xianglian*; Bao, W.*; Guo, T.*; Li, P.*; Sakuma, Takashi*; Igawa, Naoki

International Journal of Innovation in Science and Mathematics, 5(6), p.165 - 167, 2017/11

Diffuse neutron scattering measurements were performed on powder $$beta$$-PbF$$_{2}$$ at 633 K. Oscillatory diffuse scattering intensities were observed and the observed diffuse scattering intensities were explained by including the correlation effects among thermal displacements of atoms. The force constants among first- and second-nearest-neighboring atoms in $$beta$$-PbF$$_{2}$$ calculated from the values of correlation effects and Debye-Waller temperature parameters were determined as 0.36 eV/ $AA $^{2}$$ at ${it r}$ = 2.599 ${AA}$ and 0.21 eV/ $AA $^{2}$$ at ${it r}$ = 3.001 AA, respectively.

Journal Articles

Inter-atomic force constants of BaF$$_{2}$$ by diffuse neutron scattering measurement

Sakuma, Takashi*; Makhsun*; Sakai, Ryutaro*; Xianglian*; Takahashi, Haruyuki*; Basar, K.*; Igawa, Naoki; Danilkin, S. A.*

AIP Conference Proceedings 1656, p.020002_1 - 020002_4, 2015/04

 Times Cited Count:1 Percentile:51.16

Diffuse neutron scattering measurement on BaF$$_{2}$$ crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF$$_{2}$$ was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. From the values of correlation effects and Debye-Waller temperature parameters, force constants among the first and second nearest neighboring atoms of BaF$$_{2}$$, were determined to be 4.40 and 2.30 eV/$AA$^{2}$$ at 295 K, respectively

Journal Articles

Estimation of force constants of Al from diffuse neutron scattering measurement

Makhsun*; Hashimoto, Takuya*; Sakuma, Takashi*; Takahashi, Haruyuki*; Kamishima, Osamu*; Igawa, Naoki; Danilkin, S. A.*

Journal of the Physical Society of Japan, 83(7), p.074602_1 - 074602_4, 2014/07

 Times Cited Count:2 Percentile:23.05(Physics, Multidisciplinary)

The correlations of atomic thermal displacements in Al were obtained from the analysis of diffuse neutron scattering intensity. The interatomic force constants were determined from the correlation effects using a newly introduced equation. The derived force constants and the crystal structure of Al were used to estimate the phonon dispersion relations, phonon density of states, and specific heat by computer simulation. The calculated phonon dispersion relations and specific heat of Al are similar to those obtained from inelastic neutron scattering and specific heat measurements, respectively.

Journal Articles

An Optical design and accuracy estimation for a JT-60SA edge Thomson scattering diagnostic

Tojo, Hiroshi; Hatae, Takaki; Hamano, Takashi; Sakuma, Takeshi; Itami, Kiyoshi

Journal of Instrumentation (Internet), 8(12), p.C12025_1 - C12025_13, 2013/12

 Times Cited Count:1 Percentile:8.02(Instruments & Instrumentation)

Journal Articles

Optical designs of reflection and refraction collection optics for a JT-60SA core Thomson scattering system

Tojo, Hiroshi; Hatae, Takaki; Hamano, Takashi; Sakuma, Takeshi; Itami, Kiyoshi

Review of Scientific Instruments, 84(9), p.093506_1 - 093506_8, 2013/09

 Times Cited Count:2 Percentile:14.21(Instruments & Instrumentation)

Journal Articles

Inter-atomic force constants of Ag$$_{2}$$O from diffuse neutron scattering measurement

Wada, Tamotsu*; Sakuma, Takashi*; Sakai, Ryutaro*; Uehara, Hiroyuki*; Xianglian*; Takahashi, Haruyuki*; Kamishima, Osamu*; Igawa, Naoki; Danilkin, S. A.*

Solid State Ionics, 225, p.18 - 21, 2012/10

 Times Cited Count:6 Percentile:31.07(Chemistry, Physical)

Diffuse neutron scattering measurement on Ag$$_{2}$$O crystals was performed at 8 K and 295 K. The observed diffuse scattering intensities were analyzed by including the correlation effects among thermal displacements of atoms in Ag$$_{2}$$O. Using the values of correlation effects among neighboring atoms and the values of Debye-Waller temperature parameter, force constants among first, second and third nearest neighboring atoms have been evaluated.

Journal Articles

Inter-atomic force constants from correlation effects among thermal displacement of atoms in PbTe

Xianglian*; Sakuma, Takashi*; Mohapatra, S. R.*; Uehara, Hiroyuki*; Takahashi, Haruyuki*; Kamishima, Osamu*; Igawa, Naoki

Molecular Simulation, 38(5), p.448 - 451, 2012/04

 Times Cited Count:1 Percentile:3.23(Chemistry, Physical)

Diffuse neutron scattering measurements have been performed on powder PbTe at 10 and 294 K. Oscillatory diffuse scattering intensity is clearly observed at 294 K. Oscillatory form of the diffuse neutron scattering intensity for PbTe was explained on inclusion of correlation effects among thermal displacements of atoms. From the values of correlation effects and Debye-Waller temperature parameter, force constants among the first nearest neighboring atoms was calculated, $$alpha$$ $$_{rm Pb-Te}$$ = 215 eV/nm$$^{2}$$, and the second ones were $$alpha$$ $$_{rm Pb-Pb}$$ =108 eV/nm$$^{2}$$ and $$alpha$$ $$_{rm Te-Te}$$ = 144 eV/nm$$^{2}$$ at 294 K.

Journal Articles

Correlation effects among thermal displacements of atoms in KBr

Sakuma, Takashi*; Xianglian*; Shimizu, Norifumi*; Mohapatra, S. R.*; Isozaki, Nobuhiro*; Uehara, Hiroyuki*; Takahashi, Haruyuki*; Basar, K.*; Igawa, Naoki; Kamishima, Osamu*

Solid State Ionics, 192(1), p.54 - 57, 2011/06

 Times Cited Count:11 Percentile:48.1(Chemistry, Physical)

Diffuse neutron scattering measurements have been performed on powder KBr. The oscillatory scheme of the diffuse scattering intensity is explained by the values of correlation effects among thermal displacements of 1st, 2nd and 3rd nearest neighboring atoms which are almost the same as those in other ionic crystals. Force constants among 1st, 2nd and 3rd nearest neighboring atoms are obtained from the correlation effects at 90 K are 0.83 eV/$AA $^{2}$$, 0.50 eV/$AA $^{2}$$ and 0.41 eV/$AA $^{2}$$, respectively.

Journal Articles

Force constants of Cu crystals from diffuse neutron scattering measurement

Sakuma, Takashi*; Mohapatra, S. R.*; Uehara, Hiroyuki*; Sakai, Ryutaro*; Xianglian*; Takahashi, Haruyuki*; Igawa, Naoki; Basar, K.*

Atom Indonesia, 36(3), p.121 - 124, 2010/12

Diffuse neutron scattering measurement on Cu crystals was performed at 10 K and 300 K and the observed diffuse scattering intensities were analyzed by including the correlation effects among thermal displacements of atoms in the theory. Using the values of correlation effects among neighboring atoms and the values of Debye-Waller temperature parameter, force constants among first, second and third nearest neighboring atoms had been evaluated. The estimated values of force constants among first, second and third nearest neighboring atoms of Cu were 5.58, 3.63 and 2.37 eV/${AA}$ $$^{2}$$ at 300 K, respectively. The relation between correlation effects and the inter-atomic distance is not depending much on the crystal binding types.

Journal Articles

Design of collection optics and polychromators for a JT-60SA Thomson scattering system

Tojo, Hiroshi; Hatae, Takaki; Sakuma, Takeshi; Hamano, Takashi; Itami, Kiyoshi; Aida, Yoshiaki*; Suito, Satoshi*; Fujie, Daijiro*

Review of Scientific Instruments, 81(10), p.10D539_1 - 10D539_3, 2010/10

 Times Cited Count:10 Percentile:47.36(Instruments & Instrumentation)

Designs of collection optics for JT-60SA Thomson scattering system are presented. By using tangential (to the toroidal direction) YAG laser injection, three collection optics without strong chromatic aberrations generated by the wide viewing angle and small design volume measure almost all the radial space. For the edge plasma measurements, we optimized the channel number and wavelength ranges of band-pass filters in polychromator to reduce relative error in the electron temperature by considering the all spatial channels and double-pass laser system with different geometric parameters.

Journal Articles

Conceptual design of polychromator for Thomson scattering system in JT-60SA

Tojo, Hiroshi; Hatae, Takaki; Sakuma, Takeshi; Hamano, Takashi; Itami, Kiyoshi

Journal of Plasma and Fusion Research SERIES, Vol.9, p.288 - 293, 2010/08

Significant loss in transmissivity of the used fiber after the 18 years operations in JT-60U are found. Therefore, an optimization of the filter's configuration of the polychromator in Thomson scattering system for the high performance plasmas in JT-60SA is an essential task. Especially, loss in optical components induced by radiation from neutrons and $$gamma$$-ray should be examined. In this paper, an optimization of the filter configuration in the polychromator is executed and expected error degradation due to the radiation damages in the measurements are also estimated with a comparison between used fibers in JT-60U and radiation resistance fibers. In $$T_{rm e}$$ $$>$$ 10 keV, the time evolution of the averaged relative errors for the radiation resistance fibers increase from 3$$sim$$5% by $$sim 1%$$. However, for the used fibers in JT-60U, the errors are 7$$sim$$8% and they reaches more than 10% in some high $$T_{rm e}$$ conditions, suggesting some difficulties in the measurements.

Journal Articles

Diffuse neutron scattering calculation of spinel structure of LiMn$$_{2}$$O$$_{4}$$

Basar, K.*; Xianglian*; Sakuma, Takashi*; Takahashi, Haruyuki*; Abe, Osami*; Igawa, Naoki

AIP Conference Proceedings 1244, p.129 - 135, 2010/06

 Times Cited Count:0 Percentile:0.07

Neutron scattering experiment has been performed on powder LiMn$$_{2}$$O$$_{4}$$ with spinel structure at room temperature. The profile of diffuse scattering was analyzed including the correlation effects among thermal displacement of atoms Li-Li, Li-Mn, Li-O, Mn-Mn, Mn-O and O-O. It was found that the main contribution to the oscillatory profile of diffuse scattering intensity of LiMn$$_{2}$$O$$_{4}$$ was O-O pairs.

Journal Articles

Diffuse scattering of $$gamma$$-PbF$$_{2}$$

Xianglian*; Sakuma, Takashi*; Basar, K.*; Takahashi, Haruyuki*; Igawa, Naoki

Journal of the Physical Society of Japan, 79(Suppl.A), p.29 - 32, 2010/03

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

$$gamma$$-PbF$$_{2}$$ belongs to cubic structure with disordered arrangements of F atoms and shows high ionic conductivity at high temperature. Neutron diffuse scattering intensity measurement has been performed at 773 K. Strong and oscillatory diffuse scattering intensity has been observed. The diffuse scattering can be explained by the correlation effects among thermal displacements of atoms and the short-range order in disordered arrangements of F atoms.

Journal Articles

Estimation of inter-atomic force constants and phonon dispersion using correlation effects among thermal displacement of atoms in Ge

Sakuma, Takashi*; Mohapatra, S. R.*; Isozaki, Nobuhiro*; Uehara, Hiroyuki*; Xianglian*; Basar, K.*; Takahashi, Haruyuki*; Kamishima, Osamu*; Igawa, Naoki

Journal of Non-Crystalline Solids, 357(2), p.559 - 562, 2010/01

 Times Cited Count:2 Percentile:18.17(Materials Science, Ceramics)

The oscillatory diffuse scattering intensity of Ge was observed by neutron scattering measurement. The force constants among the first, second and third nearest neighboring atoms in Ge were determined from the values of correlation effects and Debye-Waller temperature parameters. The inter-atomic force constants among the first, second and third nearest neighboring atoms at 80 K in Ge are 363 eV/nm$$^{2}$$, 232 eV/nm$$^{2}$$ and 200 eV/nm$$^{2}$$, respectively.

Journal Articles

Correlation effects among thermal displacements of atoms from diffuse neutron scattering measurements

Sakuma, Takashi*; Mohapatra, S. R.*; Yokokawa, Jo*; Shimizu, Norifumi*; Isozaki, Nobuhiro*; Uehara, Hiroyuki*; Xianglian*; Basar, K.*; Takahashi, Haruyuki*; Kamishima, Osamu*; et al.

Proceedings of 12th Asian Conference on Solid State Ionics and 15th Chinese Conference on Solid State Ionics, p.439 - 445, 2010/00

Diffuse neutron scattering intensities from ionic crystals, covalent crystals and metal crystals are analyzed by including the correlation effects among thermal displacements of atoms into the function describing background intensity. The obtained values of correlation effects among first nearest neighboring atoms are 0.7 near room temperature. The values of the correlation effects do not depend much on the type of the crystal binding near room temperature. The values of correlation effects decrease rapidly with the increase of inter-atomic distances. The correlation effects also decrease with the decrease of temperature.

Journal Articles

Correlation effects among thermal displacements of atoms in VSe by diffuse neutron scattering measurement

Sakuma, Takashi*; Xianglian*; Siagian, S.*; Basar, K.*; Takahashi, Haruyuki*; Igawa, Naoki; Kamishima, Osamu*

Journal of Thermal Analysis and Calorimetry, 99(1), p.173 - 176, 2009/10

 Times Cited Count:3 Percentile:14.32(Thermodynamics)

Neutron diffraction measurements have been performed on powder VSe at 294 K. The diffuse scattering theory including correlation effects among thermal displacements of atoms is applied to background function in the rietveld analysis. The oscillatory scheme of the diffuse scattering intensity from hexagonal VSe is explained by the correlation effects among far-neighboring Se-Se atoms. The values of the correlation effects depend on the inter-atomic distance and not on the crystal structure.

Journal Articles

Development of polarization interferometer for Thomson scattering diagnostics in JT-60U

Hatae, Takaki; Howard, J.*; Ebizuka, Noboru*; Hirano, Yoichi*; Koguchi, Haruhisa*; Kitamura, Shigeru; Sakuma, Takeshi; Hamano, Takashi

Journal of Plasma and Fusion Research SERIES, Vol.8, p.680 - 684, 2009/09

A polarization interferometer based on the Fourier transform spectroscopy for the Thomson scattering diagnostics is being developed to evaluate the validity. At the first stage, a dual channel polarization interferometer utilizing a fixed-thickness birefringent plate is developed, and the target $$T_{e}$$ and $$n_{e}$$ ranges were $$<$$ 1 keV and $$>$$ 5$$times$$10$$^{18}$$ m$$^{-3}$$, respectively. The electron temperature is successfully measured by the dual channel polarization interferometer in TPE-RX reversed field pinch machine, for the first time. The temperature of the polarization interferometer nearly agrees with that of the filter polychromator. At the second stage, we are developing a multichannel polarization interferometer employing a Wallaston prism to cover wider range of electron temperature. Interferograms of three kinds of light sources are measured by the multichannel polarization interferometer, and those spectra are reconstructed by Fourier transform. In the measurement of a blackbody radiation source using the multichannel polarization interferometer, both ideal and measured spectra agree within 8%.

Journal Articles

Diffuse neutron scattering of KBr at room temperature and its application as background function in rietveld analysis

Basar, K.*; Xianglian*; Sakuma, Takashi*; Takahashi, Haruyuki*; Igawa, Naoki

ITB Journal of Science, 41A(1), p.50 - 58, 2009/05

Diffuse neutron scattering profile of KBr at room temperature was explained by including the correlation among thermal displacement of atoms up to third neighbor atom in the crystal KBr. The values of correlation effects decrease with inter-atomic distance. The diffuse scattering theory including correlation effects is applied as background function in Rietveld analysis.

Journal Articles

Inter-atomic distance and temperature dependence of correlation effects among thermal displacements

Xianglian*; Siagian, S.*; Basar, K.*; Sakuma, Takashi*; Takahashi, Haruyuki*; Igawa, Naoki; Ishii, Yoshinobu*

Solid State Ionics, 180(6-8), p.480 - 482, 2009/05

 Times Cited Count:3 Percentile:18.05(Chemistry, Physical)

Correlation effects among thermal vibrations of atoms are very important to realize the thermal properties of materials. We discuss the inter-atomic distance and temperature dependence of the correlation effects in ionic crystal, AgBr, CuBr, CuI and CuCl, by neutron diffraction method. From the Rietveld analysis of those diffraction data the lattice constants and Deby-Waller parameters were determined. The diffuse scattering of diffraction data was analyzed with the correlation effect, $$mu$$. It is found that the $$mu$$ is 0.6-0.75 for the inter-atomic distance around 2.5${AA}$ and 0.4-0.5 for 4${AA}$ for all ionic crystals. The value of $$mu$$ decreases with the decrease of temperature.

Journal Articles

Correlation effects among atomic thermal displacements in oscillatory diffuse neutron scattering of ZnSe

Basar, K.*; Siagian, S.*; Xianglian*; Sakuma, Takashi*; Takahashi, Haruyuki*; Igawa, Naoki

Nuclear Instruments and Methods in Physics Research A, 600(1), p.237 - 239, 2009/02

 Times Cited Count:9 Percentile:56.98(Instruments & Instrumentation)

Neutron scattering measurements have been performed on powder ZnSe at 15, 150 and 300 K. The oscillatory diffuse neutron scattering intensity is explained by including the correlation effects among atomic thermal displacement of the first, second and third nearest neighboring atoms. It was found that the values of correlation effects decrease by increasing inter-atomic distances and with the decrease of temperature.

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