Size- and shape-dependent phase diagram of In-Sb nano-alloys

Nano-scale alloy systems with at least one dimension below 100 nm have different phase stabilities
than those observed in the macro-scale systems due to a large surface to volume ratio. We
have used the semi-empirical thermodynamic modelling, i.e. the CALPHAD method, to predict the
phase equilibria of the In-Sb nano-scale systems as a function of size and shape. To calculate the
size- and shape-dependent phase diagram of the In-Sb system, we have added size-dependent
surface energy terms to the Gibbs energy expressions in the In-Sb thermodynamic database. We
estimated the surface energies of the solution phases and of the InSb intermetallic phase using
the Butler equation and DFT calculations, respectively. A melting point and eutectic point depression
were observed for both nanoparticle and nanowire systems. The eutectic composition on the
In-rich and Sb-rich sides of the phase diagram shifted towards higher solubility. We believe that
the phase diagram of In-Sb nano-alloys is useful for an increased understanding of the growth
parameters and mechanisms of InSb nanostructures.