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Journal Articles

Study of quantum effects on atomic displacements in quartz

Fujishita, Hideshi*; Hayashi, Makoto*; Kanai, Takashi*; Yamada, Takahiro*; Igawa, Naoki; Kihara, Kuniaki*

Journal of Physics and Chemistry of Solids, 71(9), p.1285 - 1289, 2010/09

 Times Cited Count:3 Percentile:17.22(Chemistry, Multidisciplinary)

Atomic displacements are order parameters for displacive structural phase transitions. The temperature evolution of Si atomic displacement in quartz was analyzed by studying the quantum expansion of the Landau potential. The expansion was found to accurately describe the evolution of the atomic displacement over the entire temperature interval. A proportional relationship between spontaneous strain and the square of the atomic displacement was observed over the entire temperature interval.

JAEA Reports

Selection of main nuclides from the viewpoint of safety assessment for near surface disposal of low-level radioactive waste generated from research, industrial and medical facilities, 3; Preliminary selection of important radionuclides contained in low-level radioactive waste generated from major research facilities

Sakai, Akihiro; Amazawa, Hiroya; Nakata, Hisakazu; Takahashi, Kuniaki; Kihara, Shinji

JAEA-Technology 2010-021, 152 Pages, 2010/07

JAEA-Technology-2010-021.pdf:7.87MB

Total radioactivity and radioactive concentration limit of nuclides in low level radioactive waste that are expected to cause relatively large dose in near surface disposal are needed to be described in the licensing application form, as so-called "main nuclides", for disposal business of LLW generated from research, industrial and medical facilities. In this report, as an example, the main nuclides were preliminarily selected out of the nuclides contained in LLW generated from main research reactors and PIE facilities in Nuclear Science Research Institute of JAEA, by use of nuclide composition ratios in the wastes and their radioactivity concentration limit of near surface disposal derived by Nuclear Safety Commission in Japan. As results of preliminary selection of main nuclides without fixed radioactive inventory in the wastes, 24, 30 and 33 nuclides were selected as main nuclides for LLW from the reactors, PIE facilities, and both facilities, respectively.

JAEA Reports

Analysis of the radioactivity concentrations in asphalt- or cement-solidified products generated from research facilities

Hoshi, Akiko; Kameo, Yutaka; Katayama, Atsushi; Sakai, Akihiro; Tsuji, Tomoyuki; Nakashima, Mikio; Kihara, Shinji; Takahashi, Kuniaki

JAEA-Data/Code 2009-023, 84 Pages, 2010/03

JAEA-Data-Code-2009-023.pdf:12.81MB

In order to establish the practical evaluation methods such as scaling factor method to determine the radioactivity concentrations of the important nuclides for safety assessment of disposal of radioactive wastes, we analyzed low-level radioactive liquid waste (56 samples), which is generated from various research facilities at Nuclear Science Research Institute from FY1998 to FY2007 and accumulated the radioactivity concentrations data (563 data) of the 17 important nuclides. We investigated the correlation of the radioactivity concentrations of the important nuclides with the "Key nuclides ($$^{60}$$Co or $$^{137}$$Cs)". In present paper, the radioactivity concentrations data of the 17 important nuclides and the results of the correlation of the radioactivity concentrations are summarized for the data to establish the practical evaluation methods to determine the radioactivity concentrations in asphalt-solidified or cement-solidified products.

Oral presentation

A Study of quantum effects on atom displacements in quartz

Hayashi, Makoto*; Kanai, Takashi*; Yamada, Takahiro*; Fujishita, Hideshi*; Igawa, Naoki; Kihara, Kuniaki*

no journal, , 

While the temperature change of the static order paramaters, such as an atom displacement and lattice destortion around the phase transition temperature is exlained by the classical Landau theory, the tempereture dependence of those parameters below the transition temperature was predicted by Salje. In this report, temperature dependence of strucural parameters of quartz was measured using the nuetron powder diffraction and analyzed by the Rietveld method to confirm the theory predicted by Salje. The quantitative analysis of present works gave a good agreement with the theory.

Oral presentation

Neutron diffraction study of quantum effects on structural phase transition in quartz

Hayashi, Makoto*; Fujishita, Hideshi*; Kanai, Takashi*; Yamada, Takahiro*; Igawa, Naoki; Kihara, Kuniaki*

no journal, , 

A phenomenological theory describes the temperature dependence of the order parameter Q, which is atomic shift in displacement structural phase transition and of strain e, which is coupled to Q, near a phase transition. Recently, Romero and Salje showed the strain obeys the quantum phenomenological theory below the temperature of the displacement structural phase transition. However, direct evaluation of the quantum phenomenological theory by measuring the order parameters in entire temperature is required to verify the effectiveness of the theory. We carried out the structural analysis of quartz by neutron powder diffraction in the temperature range of 10-250K. We found that the strain was in proportion to the squares of the displacement of the Si atom along the a-axis in the present temperature range. The effectiveness of the theory was directly verified by the atomic displacement.

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