The cubic structure of LiAs stabilized by substitution - LiTtAs (Tt = Si, Ge) and LiTtAs (Tt = Si, Ge, Sn) and their lithium ion conductivity.

The new lithium arsenidotetrelates LiSiAs, LiGeAs, LiSiAs, LiGeAs and LiSnAs were synthesized ball milling and structurally characterized by Rietveld analysis of X-ray powder diffraction data. The aliovalent substitution of lithium in hexagonal LiAs by introducing a tetravalent tetrel cation stabilizes cubic structures for LiTtAs (Tt = Si, Ge) in the space group 3̄ and for the lithium richer compound LiTtAs (Tt = Si, Ge, Sn) in the higher symmetrical space group 3̄ (no. 225). Thermal properties of the arsenidotetrelates were investigated high temperature powder diffraction and differential thermal analysis revealing a decomposition process of the lithium richer arsenidotetrelate (LiTtAs → LiTtAs + 2LiAs) into the lithium poorer arsenidotetrelates and lithium arsenide at moderate temperatures. Impedance spectroscopy shows moderate to good lithium ion conductivity for the lithium arsenidotetrelates.