In4Te3 und In4Se3: Neubestimmung der Kristallstrukturen, druckabhängiges Verhalten und eine Bemerkung zur Nichtexistenz von In4S3

Abstract

Abstract The X-ray crystal structures of the two black, isotypic, mixed valent solids In4Te3 (a = 15.619(1) Å, b = 12.749(1) Å, c = 4.4348(3) Å, space group Pnnm, Z = 4) and In4Se3 (a = 15.296(1) Å, b = 12.308(1) Å, c = 4.0806(5) Å), were redetermined using single crystals isolated from homogeneous, microcrystalline samples. X-ray powder investigations in the composition range In4Se3−x S x (0 < x < 3) revealed heterogeneous samples for x > 1, indicating the non-existence of “In4S3” under these conditions. High pressure X-ray experiments with In4Te3 (powder and single crystals) and In4Se3 (powder) showed pronounced anisotropies of the compressibilities for the normal pressure modifications, which can be correlated to the structure and bonding situations in both compounds. At 4.1 GPa In4Te3 decomposes to In + 3InTe, the latter one crystallizing in a rocksalt structure and incorporating excess Indium in the sense In1 + x Te. At 16.0 GPa the mixture In + 3InTe undergoes a second phase transition. In4Se3 transforms to a new high pressure phase of unknown structure at 8.8 GPa.