Thermal expansion coefficients of Bi2Se3 and Sb2Te3 crystals from 10 K to 270 K

Lattice constant of Bi2Se3 and Sb2Te3 crystals is determined by x-ray powder diffraction measurement in a wide temperature range. Linear thermal expansion coefficients (alpha) of the crystals are extracted, and considerable anisotropy between alpha(parallel to) and alpha(perpendicular to) is observed. The low temperature values of alpha can be fit well by the Debye model, while an anomalous behavior at above 150 K is evidenced and explained. Gruneisen parameters of the materials are also estimated at room temperature. (C) 2011 American Institute of Physics. [doi:10.1063/1.3672198]