No abstract

Polycrystalline Bi 1-x Sb x alloys have been synthesized over a wide range of antimony concentration (0.08 < x < 0.20) by solid state reaction method. In depth structural analysis using X-Ray diffraction (XRD) and temperature dependent resistivity () measurement of synthesized samples have been performed. XRD data confirmed single phase nature of polycrystalline samples and revealed that complete solid solution is formed between bismuth and antimony.Rietveld refinement technique, utilizing MAUD software, has been used to perform detail structural analysis of the samples and lattice parameters of polycrystalline Bi 1-x Sb x alloys have been estimated. Lattice parameter and unit cell volume decreases monotonically with increasing antimony content. The variation of lattice parameters with antimony concentration depicts a distinct slope change at x = 0.12. Band gap (E g ) has been estimated from the thermal variation of resistivity data, with the 12% Sb content sample showing maximum E g . It has been observed that, with increasing antimony concentration the transition from direct to indirect gap semiconductor is intimately related to the variation of the estimated lattice parameters. Band diagram for the polycrystalline Bi 1-x Sb x alloy system has also been proposed.

Structural and thermoelectric properties of metallic and semiconducting Sb 2 Te 3 are reported. X-Ray diffraction and Raman spectroscopy studies reveal that semiconducting sample have higher defect density. Nature and origin of possible defects are highlighted. Semiconducting Sb 2 Te 3 hosts larger numbers of defects, which act as scattering center and give rise to the increased value of resistivity, thermopower and power factor. Thermopower data indicates p-type nature of the synthesized samples. It is evidenced that the surface states are often mixed with the bulk state, giving rise to metallicity in Sb 2 Te 3 . Role of different scattering mechanism on the thermoelectric property of Sb 2 Te 3 is discussed.

No abstract

No abstract