Tuning of thermoelectric properties with changing Se content in Sb2Te3

Polycrystalline Sb 2 Te 3-x Se x (0.0 < x < 1.0) samples were synthesized by the solid state reaction method. The structural analysis showed that up to the maximal concentration of Se, the samples possess the Rhombohedral crystal symmetry (space group R 3 m ). Increase of Se content increases the resistivity of the samples. Variation of phonon frequencies, observed from Raman spectroscopic study, depict anomalous behaviour around x = 0.2. The sample Sb 2 Te 2.8 Se 0.2 also shows maximum Seebeck coefficient, carrier concentration and thermoelectric power factor. Nature of scattering mechanism controlling the thermopower data has been explored. The thermoelectric properties of the synthesized materials have been analyzed theoretically in the frame of Boltzmann equation approach.