Structural transitions and magnetocaloric properties of low-cost MnNiSi-based intermetallics

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Study of the magnetostructural transition in critical-element free Mn1−xNi1−xFe2xSi0.95Al0.05

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Characterizing the ZrBe2Hx Phase Diagram via Neutron Scattering Methods

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Exploring V-Fe-Co-Ni-Al and V-Fe-Co-Ni-Cu high entropy alloys for magnetocaloric applications

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Hydrogen storage in complex hydrides: past activities and new trends

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On the Crystal Chemistry of Photochromic Yttrium Oxyhydride

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Nanostructured MgH2 obtained by cold rolling combined with short-time high-energy ball milling

MgH2 was processed by short time high-energy ball milling (BM) and cold rolling (CR). A new alternative processing route (CR + BM) using the combination of CR followed by short time BM step was also applied. The effects on the final morphology, crystalline structure and H-sorption properties were evaluated. The CR + BM processing (compared to BM and CR process) resulted in an inhomogeneous particle size distribution and the biggest crystallite size of MgH2, showing that there is a clear dependence between the size/shape of the particles which compose the starting material and the efficiency of crystallite size reduction during the BM process. On the other hand, we observed that a short BM step improved the kinetic properties of the cold rolled material. It shows that the particle size reduction of MgH2 obtained by CR combined with the increase in specific surface area attained by short BM step could be key factors to allow the use of the CR + BM route

On the Crystal Chemistry of Photochromic Yttrium Oxyhydride

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Revisiting the Crystal Structure of Rhombohedral Lead Metaniobate

Lead metaniobate (PbNb₂O₆) can exist both as a stable rhombohedral and a metastable orthorhombic tungsten-bronze-type polymorph. Although the orthorhombic is a well-known ferroelectric material, the rhombohedral polymorph has been far less studied. The crystal structure and energetic stability of the stable rhombohedral polymorph of lead metaniobate is re-examined by powder X-ray diffraction and powder neutron diffraction in combination with ab initio calculations. We show that this structure is described by the polar space group <i>R</i>3, in contradiction to the previously reported space group <i>R</i>3<i>m</i>. The crystal structure is unusual, consisting of edge-sharing dimers of NbO_6/2 octahedra forming layers with 6- and 3-fold rings of octahedra and lead ions in channels formed by these rings. The layers are connected by corner-sharing between octahedra. Finally, the crystal structure is discussed in relation to other AB₂O₆ compounds with B = Nb, Ta