Structural and electrical properties of (PbSe)_1·16TiSe₂

The synthesis and characterization of a new layered compound with the composition (PbSe)_1·16TiSe₂ in thin-film form is reported in this study. The structure of the new compound was characterized by specular and in-plane synchrotron x-ray diffraction studies, which indicate that the compound can be described as a layered intergrowth of PbSe and TiSe₂ in which the individual constituents are precisely layered yet rotationally (turbostratically) disordered with an average in-plane domain size in the order of 10 nm. In contrast to crystalline (PbSe)_1·16(TiSe₂)₂ prepared by solid-state reaction at high temperature, the electrical resistivity in the range 20–300 K is nearly temperature independent. The Seebeck coefficient at room temperature was measured to be S = −66(1) μV/K at the carrier concentration of n = 2·1(5) × 10²¹ cm⁻³, indicating behavior characteristic of a heavily doped semiconductor. The electrical transport properties for the (PbSe)_1·16TiSe₂ compound are compared and contrasted to those of other misfi t-layered and turbostratically disordered (MX)_1+δ(TX₂)_n compounds.