Synthesis and Crystal Structure of RbKLiAlF6 – the First Al‐Elpasolite with Three Different Alkali Metals

The synthesis of RbKLiAlF₆ via a sol‐gel route is described. The crystal structure has been determined using Rietveld‐refinement. It is shown that the compound crystallizes in the hexagonal 12L‐structure of the Cs₂NaCrF₆‐type (space‐group ) with a = 5.7195Å, c = 27.8655(4) Å and therefore belongs to the family of hexagonal elpasolites being the first example for an Al‐elpasolite with three different alkali metals. Further insights regarding structural details could be gained using ⁸⁷Rb MAS NMR spectroscopy.