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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:13.67(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

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:17.59(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:55.88(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.

Journal Articles

Anneal temperature effect on crystallite size and electric conductivity of LiMn$$_{2}$$O$$_{4}$$

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

Indonesian Journal of Physics, 20(1), p.9 - 11, 2009/01

Nanosized LiMn$$_{2}$$O$$_{4}$$ has been successfully prepared by solid state reaction of LiOH and MnO$$_{2}$$. Neutron scattering experiments at room temperature and conductivity measurement have been performed on the samples. Anneal temperature effect on the crystallite size and electric conductivity of LiMn$$_{2}$$O$$_{4}$$ is analyzed. The average crystallite size is obtained from the full width at half maximum (FWHM) of Bragg lines using Scherrer equation. The average crystallite size increases with the increase of anneal temperature. Activation energy and conductivity prefactor increase with anneal temperature.

Journal Articles

Effect of Pb-Pb correlation in diffuse scattering of powder PbF$$_{2}$$

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

Solid State Ionics, 179(21-26), p.776 - 779, 2008/09

 Times Cited Count:2 Percentile:12.47(Chemistry, Physical)

Diffuse X-ray and neutron scattering from powder PbF$$_{2}$$ are measured at 15 and 294K. Those oscillatory profile of diffuse scattering is explained by including the correlation effects among thermal displacements of atoms. The contribution of correlated thermal vibration of Pb-Pb atoms located at far-off distance to the oscillatory profile of diffuse scattering intensities is first confirmed.

Journal Articles

Oscillatory diffuse scattering study by time-of-flight neutron scattering

Basar, K.*; Xianglian*; Siagian, S.*; Sakuma, Takashi*; Takahashi, Haruyuki*; Yonemura, Masao*; Kamiyama, Takashi*; Ishigaki, Toru*; Igawa, Naoki

Physica B; Condensed Matter, 403(17), p.2557 - 2560, 2008/08

 Times Cited Count:2 Percentile:12.47(Physics, Condensed Matter)

Diffuse scattering is an important tool for analyzing disordered arrangement of atoms in crystals. In this study the oscillatory of diffuse scattering intensity of PbF$$_{2}$$ was observed both in wavelength-dispersive and angular-dispersive neutron scattering measurements, and we discuss the diffuse neutron scattering intensity by TOF measurement on powder sample of PbF$$_{2}$$ compared with those by angular-dispersive diffraction patterns. The diffuse scattering theory including the correlation effects among thermal displacements of atoms is effective for the treatment of diffuse background intensity obtained by TOF neutron experiment.

Journal Articles

Diffuse scattering study of thermal disorder in solid state ionics

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

Proceedings of 11th Asian Conference on Solid State Ionics, p.45 - 52, 2008/00

The diffuse neutron scattering intensities for CuI and AgBr were analyzed by the theory including the thermal correction effects up to 3rd nearest neighboring atoms. When we include the temperature dependence of the values of correlation effects, the obtained results by the refinement were improved than the former. The values of correlation effects decrease rapidly with the increase of inter-atomic distance. The values also decrease with the decrease of temperature.

Oral presentation

Diffuse scattering and thermal displacements of atoms

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

no journal, , 

Diffuse scatterings contain information about a short-range-order and thermal vibrations of atoms in crystals. We discuss the inter-atomic distance and temperature dependence of the correlation effects among thermal displacements of atoms. The intensity of neutron diffuse scattering for silver halides and copper halides was analyzed with the correlation effects among thermal displacements of first, second and third nearest beighboring atoms. the values of the correlation effects decrease rapidly with the increase of inter-atomic distance. Those also decrease with the decrease of temperature and the tendency of the temperature dependence agrees with that obtained by the simple Debye model of lattice vibrations.

Oral presentation

Diffuse scattering of PbF$$_{2}$$, 2

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

no journal, , 

The diffuse scattering in superionic conductive crystals includes the disorder of crystal structure and thermal vibration. We carried out the neutron diffraction experiment of PbF$$_{2}$$ in the temperature range from room temperature to 773K, and discuss the correlation effects of defects in ionic crystal and thermal vibration of atoms on the diffuse scattering.

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