Abstract
Using chemical transport reactions well-shaped crystals of In2(SO4)3 and Ga2(SO4)3 can be prepared in a temperature gradient (T2 → T1) using Cl2 as transport agent. The two modifications of In2(SO4)3 were formed by variation of the transport temperature. The low-temperature modification of In2(SO4)3 (898 K → 848 K) is isostructural to monoclinic Fe2(SO4)3 and crystallizes in P21/n with a = 8.570(2) Å, b = 8.908(2) Å and c = 12.0521(1) Å, β = 91.05(3)°, Z = 4. The high-temperature modification of In2(SO4)3 (1023 K → 973 K) as well as Ga2(SO4)3 (923 K → 873 K) is isostructural to rhombohedral Fe2(SO4)3 and crystallizes in the rhombohedral space group R[unk] with a = 8.440(2) (8.054(2)) Å, c = 23.093(2) (21.840(2)) Å, Z = 6 (hexagonal setting). The crystal structures were refined to a residual R1 = 0.028 using 1710 unique reflections with Fo ≥ 4σ · (Fo) for monoclinic In2(SO4)3 and to R1 = 0.031(0.037) (571(587) unique reflections with Fo ≥ 4σ(Fo)) for rhombohedral In2(SO4)3(Ga2(SO4)3).
The structures consist of MO6-octahedra and SO4-tetrahedra, which are linked via common corners to a three-dimensional network.
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