X-ray diffraction study of Ge-Bi-Te mixed-layer ternary compounds

The structures of the Ge3Bi6Te10, GeBi6Te10, and Ge2Bi10Te17 compounds, belonging to the nGeTe . mBi(2)Te(3) homologous series, were studied by x-ray diffraction, For Ge3Bi2Te6, the atomic coordinates, lattice parameters, and interatomic distances were determined. This compound was shown to contain mixed (Ge + Bi) cation layers. The c parameters of the hexagonal cells of GeBi6Te10 and Ge2Bi10Te17 were determined. It is shown that the x-ray patterns from the cleaved surfaces of single-crystal nGeTe . mBi(2)Te(3) compounds vary in a systematic manner with increasing nlm ratio, which is attributable to the filling of empty Te octahedra. For 00l reflections, index I can be expressed in general form through n and m.