Li + Ion Conductors with Adamantane-Type Nitridophosphate Anions β-Li 10 P 4 N 10 and Li 13 P 4 N 10 X 3 with X=Cl, Br

• Published in: Chemistry : a European journal 2018-01, Vol.24 (1), p.196-205
• Main Authors: Bertschler, Eva-Maria, Dietrich, Christian, Leichtweiß, Thomas, Janek, Jürgen, Schnick, Wolfgang
• Format: Article
• Language: English
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201704305

β-Li P N and Li P N X with X=Cl, Br have been synthesized from mixtures of P N , Li N, LiX, LiPN , and Li PN at temperatures below 850 °C. β-Li P N is the low-temperature polymorph of α-Li P N and crystallizes in the trigonal space group R3. It is made up of non-condensed [P N ] T2 supertetrahedra, which are arranged in sphalerite-analogous packing. Li P N X (X=Cl, Br) crystallizes in the cubic space group Fm3‾m . Both isomorphic compounds comprise adamantane-type [P N ] , Li ions, and halides, which form octahedra. These octahedra build up a face-centered cubic packing, whose tetrahedral voids are occupied by the [P N ] ions. The crystal structures have been elucidated from X-ray powder diffraction data and corroborated by EDX measurements, solid-state NMR, and FTIR spectroscopy. Furthermore, we have examined the phase transition between α- and β-Li P N . To confirm the ionic character, the migration pathways of the Li ions have been evaluated and the ion conductivity and its temperature dependence have been determined by impedance spectroscopy. XPS measurements have been carried out to analyze the stability with respect to Li metal.