Evidence for the existence of an unusual structure in the nanorods of InSb

Motivated by the recent prediction that InSb nanometer-diameter filaments can exhibit exotic physical properties, we have synthesized this material and have characterized the filaments. In this report, we describe the finding of an unusual phase of InSb. This new phase occurs when an InSb filament has a diameter of less than 100 nm. High-resolution X-ray-diffraction studies of InSb filaments, having radii ≅33.0 nm, indicate the InSb crystal lattice to be tetragonal, S.G. I4/mmm, with a unit-cell volume 12 times larger than that of the β-tin phase observed in bulk InSb above 2.0 GPa. The density of an InSb nanorod, as calculated from X-ray-diffraction data, is ∼22% more than that of the zinc-blende phase of InSb at ambient conditions, implying that the nanorod experiences a pressure of ∼2 GPa. In contrast, InSb nanorods with radii ≥50.0 nm are observed to show zinc-blende structure and densities nearly the same as that of the bulk. Received: 6 February 2002 / Accepted: 26 March 2002 / Published online: 10 September 2002 RID="*" ID="*"Corresponding author. Fax: +1-202/767-5301; E-mail: yousuf@seas.gwu.edu