The crystal structure of (Mg,Ga)8(Ga,Ge)2O12

The crystal structure of the compound (Mg 13.7 Ga 2.3 )(Ga 2.3 Ge 1.7 )0 24 , forming as part of the solid solution (Mg,Ga) 8 (Ga,Ge) 2 O 12 in the MgO – Ga 2 O 3 – GeO 2 system, has been determined by single-crystal X-ray diffraction. Crystal data: M r = 1161.16, orthorhombic, Cmmm space-group (No-65), Z = 1, F (000) = 5555.17, λ (Mo Kα ) = 0.71069 Å, T = 295(1) K, a = 5.8475(8) Å, b = 25.474(4) Å, c = 2.9824(6) Å, V = 444.3(1) Å 3 , D c = 4.339 Mg · m −3 , μ (Mo Kα ) = 108.90 cm −1 , R = 0.036, wR = 0.032 for 425 independent reflections. The structure is based on a slightly distorted ccp oxygen array with Ga and Ge atoms randomly distributed on the tetrahedral sites but Mg and Ga atoms strongly ordered on the octahedral sites. The structure can be described as an intergrowth of the rock-salt and β -gallia structure-types.