Fig.1 Aberration-corrected Lorentz image (left) and in-plane magnetization (right) for Dy at 127K, showing coexistence of magnetic soliton and the helical AFM phase.Fig. 1 In situ EELS spectra for Ni L edge under different conditions.72Lorentz microscopy is a modern TEM-based technique for magnetic imaging. However, the spatial resolution of Lorentz images is considerably reduced by the spherical aberration (Cs) and chromatic aberration (Cc) of the weakly excited Lorentz lens. We have therefore used an image Cs corrector and a monochromator simultaneously to reduce both aberrations for sake of the drastic improvement of the resolution, leading real-space observation of the magnetic phase separation in a single crystal of dysprosium (Dy) [1]. Figure 1 shows the in-plane magnetization distribution for Dy at 127K, obtained by the aberration-corrected Lorentz microscopy combined with the transport-of-intensity equation (TIE) method. Coexistence of magnetic soliton, an isolated single domain of the ferromagnetic phase, and the helical antiferromagnetic (AFM) phase is successfully visualized.Dry reforming of methane (DRM, CH4 + CO2 → 2H2 + 2CO) is a powerful reaction utilizing the two greenhouse gases for a global warming issue. Ni-based catalysts are useful owing to their high catalytic activities and lower cost. But they are easily deactivated by carbon deposition (coking) during DRM reactions. In this work, structural and chemical changes of Ni nanoparticles on Al2O3 support during DRM process were investigated through in-situ scanning transmission electron microscopy (STEM) with electron energy-loss spectroscopy (EELS) analysis, which were performed by using a developed gas environment heating specimen holder system [1]. While the Ni nanoparticles were mainly metallic Ni before the DRM gas flowing, most of the nanoparticles changed from Ni to oxidized Ni or from oxidized Ni to reduced Ni depending on temperature after the gas flowing. In addition, structural changes of the Ni nanoparticles were observed with the oxidation and reduction. [1] T. Nagai et al., Phys. Rev. B, 96, 100405(R) (2017).Poster Award NomineeP4-01Visualization of Magnetic Soliton Using Aberration-Corrected Lorentz MicroscopyTakuro NagaiResearch Network and Facility Services Division, National Institute for Materials Science (NIMS)P4-02In-situ TEM Observation of Ni-based Catalysts for DRMAyako Hashimoto1,2 and Hideki Abe1,31 Research Center for Energy and Environmental Materials, National Institute for Materials Science (NIMS)2 Degree Programs in Pure and Applied Sciences, University of Tsukuba3 Graduate School of Science and Engineering, Saitama University[1] A. Hashimoto et al., Microscopy, 70, 545-549 (2021).
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