  Polycrystalline Bi-Sb alloys have been synthesized over a wide range of
antimony concentration (8 at% to 20 at%) 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 synthesized Bi-Sb
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 beyond
12 at% Sb content sample. Band gap has been estimated from the thermal
variation of resistivity data, with the 12% Sb content sample showing maximum
value. 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-Sb alloy system has also been proposed.
