Constitutional supercooling and the growth of 200 nm Bi–Sb wire array composites

Bi 1−x Sb x (x≈0.1) alloy crystals present a high thermoelectric figure of merit at T≈100 K. The alloys are difficult to grow successfully and require special techniques to avoid constitutional supercooling and the resulting segregation. We present a study of the growth of 200 nm wire arrays of Bi–Sb by high-pressure injection of the melt of the alloy in a porous template. We find that the concentration of Sb in the nanowires is much lower than the composition of the starting alloy and discuss the results in terms of a model of constitutional supercooling in restricted geometries.