The Phosphidosilicates AE 2 Li 4 SiP 4 ( AE =Ca, Sr, Eu) Ba 4 Li 16 Si 3 P 12

The quaternary phosphidosilicates AE 2 Li 4 SiP 4 ( AE =Ca, Sr, Eu) and Ba 4 Li 16 Si 3 P 12 were synthesized by heating the elements and Li 3 P under argon atmosphere. Their crystal structures were determined by single crystal X‐ray diffraction. AE 2 Li 4 SiP 4 crystallize in a new layered structure type ( P 2 1 / m , Z =2) with CdI 2 ‐analoguos layers. Edge sharing CaP 6 octahedra are separated by layers of vertex‐sharing SiP 4 and LiP 4 tetrahedra, which contain additional chains of LiP 6 octahedra. Ba 4 Li 16 Si 3 P 12 forms likewise a new structure type ( P 2 1 / c , Z =16) with a three‐dimensional network of SiP 4 , Si 2 P 6 and LiP 4 entities as well as one phosphorus site not bonded to silicon. Barium is located in capped trigonal prisms of phosphorus which form strongly corrugated layers. 31 P and 29 Si solid‐state NMR spectra confirm the crystal structures of the compounds AE 2 Li 4 SiP 4 . 7 Li spectra show only one signal in spite of quite different crystallographic positions, which indicate possible Li + mobility. However, this signal is much broader compared to the known Li + conducting phosphidosilicates. Accordingly, electrochemical impedance measurements show low Li + conductivities.