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Acta Cryst. (2014). A70, C152
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RMn2O5 (R = Y, Bi, rare-earth) is one of the prototypical multiferroic materials that exhibits a rich variety of magnetoelectric effects. Since the successive magnetic and ferroelectric phase transitions simultaneously take place, magnetic order has been thought to be a primary order parameter for the ferroelectricity in this system. We recently have found that in neutron diffraction study of 153EuMn2O5, magnetic phase transition is induced by applying hydrostatic pressure. As temperature decreases upon p = 1.4 GPa, the magnetic propagation wave vector changes from qM = (1/2, 0, 1/3) to (1/2, 0, 1/2), indicating that the period of magnetic unit cell as well as the magnetic structure change at the phase transition. We have also carried out the dielectric and polarization measurements under pressure and established magnetic and dielectric phase diagram as functions of temperature and pressure as shown in the figure. This study has revealed that the ferroelectric (FE1) - ferroelectric (FE2) phase transition concomitantly occurs at the magnetic phase transition, where the electric polarization is enhanced. To clarify the relevance between the ferroelectricity and the magnetic structure, we carried out single crystal magnetic structure analysis of 153EuMn2O5 upon ambient- and high-pressure. In the magnetic phase with qM = (1/2, 0, 1/3), cycloidal magnetic structure of manganese spins propagating along c-axis is realized. On the contrary in the magnetic phase with qM = (1/2, 0, 1/2), the spins arrange almost collinearly along c-axis. The result indicates that the presence of the cycloidal spin structure plays an important role for inducing (or reducing) the electric polarization in this compound. This study was supported by "KAKENHI"-programs of Scientific Research (B) (24340064), Scientific Research (A) (21244051), Challenging Exploratory Research (23654098) and of Scientific Research on Priority Areas "Novel States of Matter Induced by Frustration" (19052001).

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Acta Cryst. (2014). A70, C359
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Ex-situ and in-situ neutron diffraction experiments were performed at HRFD time-of-flight (TOF) diffractometer (IBR-2 long-pulsed reactor, JINR) to characterize the entire battery system based on LiFePO4 and V-added LiFePO4 electrodes during electrochemical cycling and to find additional information about crystal structure of electrodes. Another purpose of this work was checking possibilities for in-situ experiments with real Li-ion batteries at the IBR-2 pulsed reactor. An important advantage of TOF method is the possibility to work at the fixed geometry of the experiment, which allows selecting the optimal battery orientation relative to the directions of the incident and scattered neutron beams and, thus, to minimize the difficulties associated with complex internal structure of the battery. It was shown that charge/discharge process of Li-based real Li-ion battery can be effectively studied by TOF technique at the IBR-2 pulsed reactor. Three full charge/discharge cycles were realized at room temperature (~170C) with slow rate. The step-like appearance of several LiCn phases was observed and the volume fractions of LiFePO4 and FePO4 structural phases at different states of charge were determined. The analysis of changes in cathode material microstructure when doped with vanadium showed a significant increase in the density of defects, which correlates with better electrochemical properties of V-added LiFePO4 compared to pure LiFePO4.

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Acta Cryst. (2014). A70, C687
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"A new single crystal neutron diffractometer by using a curved two-dimensional position sensitive detector (C-2DPSD) has been installed at HANARO-ST3 beam port [1]. Compared with a conventional point detector, a two-dimensional detector has huge reciprocal space information in general. It has advantages to detect superlattice peaks and diffuse scattering etc. without any pre-information. In order to obtain significant diffraction intensity in the reciprocal space, it is essential the efficient program for handling the measuring data directly. In these several years, we have developed the methodology and the program package "Reciprocal Analyzer", based on many experiments by the C-2DPSD, which includes peak search [2], UB matrix determination, and quantitative assessment of the accurate integrated intensities [3]. And to visualize reciprocal space from raw pixel data of the C-2DPSD, the ""Reciprocal Viewer"" has been developed also. These software are coded by C/C++ and Python with OpenGL as a cross-platform GUI. Figures show the graphical interface of Recipocal Analyzer and Viewer. Details of the feature about these software will be introduced at the presentation."

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Acta Cryst. (2014). A70, C1703
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The crystal structure of Li(ND4)SO4 was analysed by neutron diffraction method. The crystal is a partially deuterated Li(NH4)SO4 and one of the ferroelectric materials with hydrogen atoms. The crystal is orthorhombic at room temperature with lattice parameters of a=5.2773(5) Å, b=9.124(2) Å, c=8.772(1) Å and Z=4. Neutron intensity data were collected on the Four-Circle Diffractometer (FCD) at HANARO in Korea Atomic Energy Research Institute. The structure was refined by full-matrix least-square to final R value of 0.049 for 745 observed reflections by neutron diffraction. All atomic positions of four hydrogen atoms at NH4 and the occupation factors of D and H were refined. From these results we obtained the average chemical structure of this sample, LiND3.05H0.95SO4. Five years later, neutron intensity data were collected and analysed once more with same crystal. The crystal is orthorhombic but with different lattice parameters, or hexagonal. We will report and discuss these results in this presentation.
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