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At least 685 records · Page 38

Large scale and fast synthesis of multiferroic TbMn{sub 2}O{sub 5} single-crystalline nanorods

Graphical abstract: - Highlights: • Pure TbMn{sub 2}O{sub 5} phase was synthesized in a wide temperature range for a short time. • Smooth and uniform single-crystalline nanorods were obtained. • The element Mn in TbMn{sub 2}O{sub 5} exhibits a mix Mn{sup 3+/4+} valence state with an average value of 3.5+, and the element Tb exhibits Tb{sup 3+}. - Abstract: Crystalline multiferroic TbMn{sub 2}O{sub 5} nanorods were successfully synthesized by a facile and scalable molten salt synthesis with NaCl–Na{sub 2}SO{sub 4} eutectic salts used in the temperature range of 750–900 °C for only 2 h. The obtained TbMn{sub 2}O{sub 5} could be indexed to an orthorhombic phase by the results of XRD patterns. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), combined with high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and EDS, have been employed to investigate the morphology, size, crystallinity, structure, and composition of the as-synthesized TbMn{sub 2}O{sub 5} nanorods. The TbMn{sub 2}O{sub 5} product exhibits smooth, uniform and crystalline nanorods with diameters of 30–70 nm, and length of varying from 3 to 6 μm. The results of X-ray photoelectron spectroscopy (XPS) analysis indicate that the elements Mn and Tb in TbMn{sub 2}O{sub 5} exhibit Mn{sup 3+/4+} and Tb{sup 3+}, respectively. The magnetic properties of the as-prepared TbMn{sub 2}O{sub 5} nanorods have been also characterized by physical properties measurement system (PPMS)

36 MATERIALS SCIENCE↗

Meso-scale anisotropic hydrogen segregation near grain-boundaries in polycrystalline nickel characterized by EBSD/SIMS

To study anisotropic hydrogen segregation and diffusion in nickel polycrystalline, Secondary Ion Mass Spectrometry (SIMS) and Electron Back Scattered Diffraction (EBSD) are integrated to investigate hydrogen distribution around grain boundaries. Hydrogen distribution in pre-charged samples were correlated with grain boundary character by integrating high-resolution grain microstructure from EBSD inverse pole figure map and low-resolution hydrogen concentration profile map from SIMS. This multimodal imaging instrumentation shows that grain boundaries in nickel can be categorized into two families based on behavior of hydrogen distribution crossing grain boundary: the first one includes random grain boundaries with fast hydrogen diffusivity, showing a sharp gap for hydrogen concentration profile cross the grain boundaries. The second family are special Σ3n grain boundaries with low hydrogen diffusivity, showing a smooth gradient of hydrogen concentration cross the grain boundary. Heterogeneous hydrogen distributions due to grain boundary family revealed by SIMS/EBSD on mesoscale further validate the recent hydrogen permeation data and anisotropic ab-initio calculations in nanoscale. The results highlight the fact that grain boundaries character impacts hydrogen distribution significantly.

Electron Back Scattered Diffraction↗