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Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.
Physica B; Condensed Matter, 551, p.291 - 296, 2018/12
Times Cited Count：11 Percentile：47.29(Physics, Condensed Matter)There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.
Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.
no journal, ,
There are many polyvalent liquid metals with complex structure which cannot be reproduced by random packing model. To explain such complexity, coexistence of metallic and covalent bonds, dynamic model of short-lived covalent bonds, and quasi-crystal model where Peierls distortion still remains even in liquid phase have been proposed from structure analyses and theoretical calculations. To obtain concrete picture experimentally for complex structure, it is indispensable to measure dynamic structure with precise statistical accuracy. We performed inelastic neutron scattering of liquid bismuth by using AMATERAS installed at MLF in J-PARC and deduced its time-space correlation function. We got evidence that structure of Peierls distortion remains even in liquid by evaluating difference in relaxation time at specific atomic distances characterized by double layered structure.
Hemmi, Tsutomu; Kajitani, Hideki; Matsui, Kunihiro; Mizutani, Takumi; Yamane, Minoru; Sakaguchi, Kaori; Ando, Shinji; Takano, Katsutoshi; Koizumi, Norikiyo
no journal, ,
JAEA has responsibility of procurement of 9 ITER Toroidal Field (TF) coils in ITER. Prior to TF coil fabrication, JAEA started to fabricate three dummy double pancakes (DPs) in order to confirm the commissioning of the facilities for DP fabrication and establish the manufacturing process of the DP. Fabrication of the dummy DP as full-scale trials has been started from October, 2013. In this full-scale trial, the control of conductor length with 
0.01%, flatness of radial plate (RP) with 2 mm and flatness of DP after CP welding with 2 mm were achieved and conductor elongation due to heat treatment was evaluated. Based on these results, TF coil winding has been started. The conductor winding has been already completed for 11 DPs of the TF coil and 10 DPs were heat treated. The conductor elongation is within expected value of 0.02%.
Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.
no journal, ,
We have performed coherent quasielastic neutron scattering experiment for liquid polyvalent metals which has complicated static structure not reproduced by a hard-sphere packing model, by utilizing AMATERAS spectrometer in J-PARC. It has been considered that, for Bi and Sb, a double-layered structure originated from Peierls distortion which is seen in solid crystalline phase remains even in their liquid phases. We have succeeded in detection of such Peierls distortion structure in liquid by difference in structural relaxation time at corresponding charateristic interatomic distances in the deduced time-space correlation function.
Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.
no journal, ,
We have developed analysis method to reduce the so-call van Hove function, a time-space correlation function, through the regularization method for coherent quasielastic neutron scattering (QENS) of liquids. In principle, the van Hove function in r-t space can be obtained by double Fourier transform from dynamic structure factor in Q-E space. Instead of a direct function estimation of the van Hove function through the regularization method which easily involves systematical deviation of the calculated dynamic structure factor from the experimental dynamic structure factor, we used a mediation function between them and estimated it through the regularization method. We will discuss with the properties of the mediation function and the obtained van Hove function and the calculated dynamic structure factor with an example of liquid metals with complex static structure such as Bi and Sb whose QENS were measured by AMATERAS spectrometer in J-PARC.
