Oberflächen- und Raumladungseffekte in keramischem Bariumtitanat

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Aliovalent substitution in phosphide‐based materials – Crystal structures of Na 10

Funding Information: The work was carried out as part of the research project ASSB coordinated by ZAE Bayern. The project is funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy. We thank Christoph Wallach for recording the Raman spectrum. Open access funding enabled and organized by Projekt DEAL. Publisher Copyright: © 2021 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbHRecently, ternary lithium phosphides have been studied intensively owing to their high lithium ion conductivities. Much less is known about the corresponding sodium-containing compounds, and during investigations aiming for sodium phosphidotrielates, two new compounds have been obtained. The sodium phosphidoaluminumtantalate Na10AlTaP6, at first obtained as a by-product from the reaction with the container material, crystallizes in the monoclinic space group P21/n (no. 14) with lattice parameters of a=8.0790(3) Å, b=7.3489(2) Å, c=13.2054(4) Å, and β=90.773(2)°. The crystal structure contains dimers of edge-sharing [(Al0.5Ta0.5)P4] tetrahedra with a mixed Al/Ta site. DFT calculations support the presence of this type of arrangement instead of homonuclear Al2P6 or Ta2P6 dimers. The 31P and 23Na MAS NMR as well as the Raman spectra confirm the structure model. The assignment of the chemical shifts is confirmed applying the DFT-PBE method on the basis of the ordered structural model with mixed AlTaP6 dimers. Thesodium phosphidogallate Na3GaP2 crystallizes in the orthorhombic space group Ibam (no. 72) with lattice parameters of a=13.081(3) Å, b=6.728(1) Å, and c=6.211(1) Å and is isotypic to Na3AlP2. Na3GaP2 exhibits linear chains of edge-sharing 1∞[GaP4/2] tetrahedra. For both compounds band structure calculations predict indirect band gaps of 2.9 eV.Peer reviewe