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Since the operation start for J-PARC/MLF at 2008, neutron diffraction experiment using high intensity pulse neutron beam became possible. For example, if there are 1g typical oxide samples, it is possible to get one diffraction pattern in about ten minutes for `Rietveld-analysis-quality' at iMATERIA. Four neutron powder diffractometer, iMATERIA (IBARAKI Materials Design Diffractometer[1]), SPICA (special environment powder diffractometer dedicated for battery study), SuperHRPD (Super high resolution powder diffractometer, d/d = 0.03 %) and NOVA (high intensity total scattering diffractometer) are operating at J-PARC/MLF. In our previous neutron facility, the neutron intensity is not so strong to carry out routinely in operando neutron diffraction experiments. In J-PARC, however, it became possible to measure quickly changing neutron diffraction patterns in operando condition. iMATERIA is a versatile neutron diffractometer funded by Ibaraki prefecture for industrial application. In iMATERIA, Some user group was trying to in-situ measurements for battery. SPICA is optimized for an in operando neutron diffraction study to clarify the structural changes of battery materials at the atomic level. It has already typical results of time resolved measurements for a commercialized Li-ion battery. The structural changes of the material, which is dependent on the lithium content, were clearly observed. We will report the status of J-PARC/MLF diffractometers and recent result of in operando experiments.
abstracts
In majority of the crystals of pharmaceutical compounds, hydrogen bonds play a crucial role. Determination of a hydrogen position is highly important, in order to investigate hydrogen bonds especially in the case of hydrates. We have been investigating humidity-induced phase transitions of hydrates systematically [1,2]. Unique characteristics of hydration water molecules have prompted us to explore the phenomena more precisely. Neutron diffraction analysis is a powerful tool to determine hydrogen positions. However, large single crystals are required because of weak neutron diffraction intensities. Under such background, we carried out neutron powder diffraction analysis of guanosine dihydrate using the Maximum Entropy Method (MEM). Neutron powder diffraction data of guanosine dihydrate (C10H13N5O5.2H2O; crystal data: monoclinic, space group P21, a = 17.518, b = 11.278, c = 6.658 Å, β= 98.170, Z = 4) were measured by iMATERIA at MLF in J-PARC (Figure 1(a)). Rietveld analysis was carried out using atomic coordinates of non-hydrogen atoms determined by X-ray analysis and those of hydrogen atoms which were placed on the geometrically calculated positions using the averaged X-H bond lengths determined by neutron analysis referencing the hydrogen positions estimated by X-ray analysis. Using Fo and σ by Rietveld analysis, the nuclear density distribution was calculated by MEM (Figure 1(b)). Nuclear densities of the hydrogen atoms of one water molecule (W1 in Figure 1) were elongated, which is consistent with the results of molecular dynamic simulation [2]. The effective usage of MEM to elucidate hydrogen atom positions from neutron powder diffraction data will be discussed together with that of difference Fourier calculations.
