Single crystal growth and characterization of narrow-gap (TlBiSe2)1-x-(TlBiS2) mixed crystals

Abstract

Large single crystals of the family of layered compounds (TlBiSe2)(1-x)-(TlBiS2)(x) were grown by the Bridgman-Stockbarger method for x = 0.0, 0.25, 0.50, 0.75 and 1.0. The structures of the as-grown single crystals were determined by x-ray diffraction and the lattice parameters and unit cell volumes were obtained. Infrared reflectivity measurements were also performed in the range 600-4000 cm(-1). From the analysis, the parameters epsilon(x), omega(rho) and Gamma were calculated. The electrical resistivities rho(parallel to) and rho(perpendicular to) (parallel and perpendicular to the layers, respectively) were measured as a function of temperature. From the rho(parallel to) measurements the plot of the Debye temperature versus x was calculated. An attempt was also made to correlate these physical properties with the compositional parameter x.