Bi1xSbx

Bi1-xSbx is a solid solution alloy of bismuth (Bi) and antimony (Sb), where x represents the mole fraction of Sb (0 ≤ x ≤ 1). The Bi-Sb system is studied for its tunable electronic properties and its use as a thermoelectric material. By varying x, the alloy can transition from near-bismuth behavior to near-antimony behavior, with notable changes in electrical conductivity, Seebeck coefficient, and thermal conductivity.

Crystal structure and solid solution chemistry are characteristic of Bi and Sb. Both elements crystallize in the rhombohedral A7 structure at room temperature, and Bi1-xSbx alloys maintain a related crystal framework across a wide composition range. Lattice parameters change smoothly with composition, and Vegard-like behavior is often observed as x is varied. The phase diagram indicates a largely continuous solid solution, with the possibility of composition-dependent changes in carrier concentration and effective mass.

Electronic structure and topological aspects are central to Bi1-xSbx. Pure Bi is a semi-metal, while Sb doping tunes the band structure toward a narrower gap or semiconducting behavior depending on composition. A portion of the composition range, roughly around low Sb contents, has been reported to host a three-dimensional topological insulator state, with surface states protected by time-reversal symmetry. This topological character has attracted interest for fundamental studies and potential electronic applications.

Thermoelectric properties are a major motivation for studying Bi1-xSbx. The alloy combines relatively large Seebeck coefficients with low lattice thermal conductivity, and the thermoelectric figure of merit can be improved by doping and microstructural engineering. Applications include room-temperature and near-room-temperature thermoelectric cooling and power generation, as well as research on topological-insulator behavior.

Synthesis typically involves melting Bi and Sb of high purity followed by annealing and controlled solidification, or mechanical alloying followed by annealing to achieve homogeneous compositions.