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

Bi1-xSbx (xapproximate to0.1) alloy crystals present a high thermoelectric figure of merit at Tapproximate to100 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. (C) 2002 American Institute of Physics.