The new lithium arsenidotetrelates Li8SiAs4, Li8GeAs4, Li14SiAs6, Li14GeAs6 and Li14SnAs6 were synthesized via ball milling and structurally characterized by Rietveld analysis of X-ray powder diffraction data. The aliovalent substitution of lithium in hexagonal Li3As by introducing a tetravalent tetrel cation stabilizes cubic structures for Li(8)TtAs(4) (Tt = Si, Ge) in the space group Pa (3) over bar and for the lithium richer compound Li(14)TtAs(6) (Tt = Si, Ge, Sn) in the higher symmetrical space group Fm (3) over barm (no. 225). Thermal properties of the arsenidotetrelates were investigated via high temperature powder diffraction and differential thermal analysis revealing a decomposition process of the lithium richer arsenidotetrelate (Li(14)TtAs(6) -> Li(8)TtAs(4) + 2Li(3)As) into the lithium poorer arsenidotetrelates and lithium arsenide at moderate temperatures. Impedance spectroscopy shows moderate to good lithium ion conductivity for the lithium arsenidotetrelates.

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Li3AlAs2, Li3GaAs2 and Li3InAs2 were obtained from the elements via high temperature synthesis. Li3AlAs2 and Li3GaAs2 crystallize in a distorted 2.2.1 superstructure of the antifluorite structure type. The orthorhombic crystal structure is isotypic to Li(3)AIP(2) and Li3GaP2, space group Cmce (No. 64) showing layers of condensed TrAs4-tetrahedra (Tr- Al, Ga). Li3InAs2 crystallizes isotypic to Li3InP2 in a distorted 2.2.4 antifluorite type super- structure. The crystal structure is tetragonal, space group I4(1)/ acd (No. 142), showing a 3D-network of In4As10-supertetrahedra. Structural characterization by powder X-ray diffraction, thermal analysis, conductivity measurements and band structure calculations show ion conductivity for Li(3)InAs(2 )and electronic charge transport for Li3AlAs2 and Li3GaAs2.

Phase pure Li3As and Li3P were synthesized from the elements by a high temperature route. Crystal structures were refined from powder X-ray diffraction data. The title compounds were further characterized by difference thermal analysis, temperature dependent X-ray powder diffraction and impedance spectroscopy, proving unexpected Li ion conductivity for Li3As. High pressure behaviour of the title compounds was modeled via density functional theory, confirming the experimentally reported cubic modifications of Li3P and Li3As.