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

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 Li 5 (OH) 2 Br 3 with lattice parameters a = 4.02335(1), c = 21.5638(1) Å, space group I 4̅ m 2. Phase II is Li 2 (OH)Br with lattice parameters a = 4.04594(3) Å and space group Pm 3̅ m . 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 Li 5 (OH) 2 Br 3 is characterized by anti-perovskite like double layers of composition 2 × Li 2 (OH)Br, which alternate with rock-salt like layers of composition LiBr. Results for Li 2 (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.