| Abstrakt: |
The structure of three compounds in the Cu2Se-In2Se3-Cr2Se3 system near CuInCr2Se5 is determined by single-crystal x-ray diffraction: CuInCr4Se8 (I), Cu2In2Se4 (II), and Cu0.5In0.5Se (III).Ihas a cubic (spinel type) structure:a= 10.606(4) Å,Z= 4, sp. gr.F43m.IIhas a pseudotetragonal (sphalerite type) structure:a= 5.774(2) Å,c= 11.617(6) Å. The structure ofIIwas solved in a reduced unit cell witha= 5.774(2) Å,b= 5.774(2) Å,c= 7.095(6) Å, a = 113.95(5)°, ß= 113.95(5)°, ?= 90.00(4)°,Z= 1, sp. gr.P1.IIIhas a triclinic cell (disordered structure ofII):a= 4.088(1) Å,b= 4.091(2) Å,c= 4.101(1) Å, a = 60.05(1)°, ß = 60.08(1)°, ? = 89.98(4)°,Z= 1, sp. gr.P1. The Cu and In atoms inIsit in inequivalent tetrahedral sites, and the Cr atoms reside in octahedral interstices of the close packing of Se atoms. The bond lengths are In-Se = 2.538(6), Cr(1)-Se(1) = 2.514(7), Cr(1)-Se(2) = 2.576(8), and Cu-Se = 2.437(5) Å. InII, all of the atoms sit in tetrahedral sites; the mean bond lengths are In-Se = 2.578(6) and Cu-Se = 2.44(1) Å. InIII, the Cu and In atoms are fully disordered in the same tetrahedral site; the mean Cu(In)-Se bond length is 2.508(6) Å. [ABSTRACT FROM AUTHOR] |
