The barium oxolithogallate Ba ₂ [LiGaO ₄ ] as an ordered variant of the BaZnO ₂ -type structure

Ba 2 [LiGaO 4 ] was prepared via a solid-state reaction in a weld-shut tantalum ampoule at T = 1,073–1,123 K. The quaternary barium oxolithogallate crystallizes in the trigonal crystal system and the crystal structure was solved and refined in the non-centrosymmetric space group P 3 2 21 (no. 154) with the lattice parameters a = 5.8361(4) Å and c = 13.320(2) Å. The structure can be constructed from vertex-sharing LiO 4 and GaO 4 tetrahedra forming a three-dimensional tetrahedron [LiGaO 4 ] 4− substructure. The charge of this anionic network is compensated by the Ba 2+ ions in eightfold coordination, forming irregularly shaped BaO 8 polyhedra. Ba 2 [LiGaO 4 ] was found to crystallize isotypically to the known barium oxolithoaluminate Ba 2 [LiAlO 4 ], both of which are ordered variants of the BaZnO 2 -type structure. The structure elucidated from single-crystal X-ray diffraction is representative for the powder sample and the element ratio of Ba:Ga is supported by the results of an EDX analysis.