Synthesis and transport properties of the Te-substituted homologous compounds Pb5Bi6Se14−xTex (0 ≤ x ≤ 1.0)

摘要: The crystal structure and transport properties (2–723 K) of the homologous compound Pb5Bi6Se14 with partial substitution Te for Se are studied by means powder X-ray diffraction, scanning electron microscopy, electrical resistivity, thermopower, thermal conductivity Hall effect measurements. Polycrystalline samples Pb5Bi6Se14−xTex (0 ≤ x 1.0) were prepared a two-step synthesis method based on pseudo-binary PbSe–Bi2Se3 phase diagram combined in PbSe precursor. successful insertion into was confirmed diffraction microscopy. Transport property measurements indicate an increase heavily doped character increasing concentration. extremely low lattice values (0.3–0.4 W m−1 K−1 at 723 that approach glassy limit high temperatures nearly independent chemical composition suggesting no influence point-defect scattering mechanisms substituted compounds. Despite inherent complexity this system, evolution electronic is well described simple single-parabolic band model. Because power factor compensated concomitant conductivity, does not yield enhanced ZT respect to pristine similar peak value 0.5 achieved K. Nevertheless, synthetic used study insert doping element opens new avenues controlling series (PbSe)5(Bi2Se3)3m (m = 1, 2 3).