Crystal structure determination of systematically intergrown compounds: Li5(OH)2Br3 and Li2(OH)Br

Abstract

Abstract We carried out a structure refinement of a crystal which was composed of two phases. Phase I was up to now unknown and corresponds to Li5(OH)2Br3 with lattice parameters a = 4.02335(1), c = 21.5638(1) Å, space group I4̅m2. Phase II is Li2(OH)Br with lattice parameters a = 4.04594(3) Å and space group Pm3̅m. The two phases have the a, b-plane in common and consequently part of the reflections overlap systematically. We performed a joint structure refinement of the two phases taking into account all reflections. The structure of Li5(OH)2Br3 is characterized by anti-perovskite like double layers of composition 2 × Li2(OH)Br, which alternate with rock-salt like layers of composition LiBr. Results for Li2(OH)Br are in good agreement with literature and confirm the correctness of the underlying model and the usefulness of the method employed in structure refinement.