Influence of nanopowder particle size on competition and growth of different crystallographic phases during temperature cycling

A model of nucleation of a new phase nucleus in an isolated nanoparticle is presented for the case of a polymorphic transition. It is shown that due to the limitation in the size of the system, a phase transition which could occur in a macroscopic sample is inhibited and situations may be realized where a metastable phase may be formed in preference to the most stable phase. We present a numerical analysis for the description of the evolution of a polymorphically transforming Fe nanoparticle ensemble subjected to temperature cycling. The time dependence of the volume fraction of the new phase is determined and the existence of a size-induced hysteresis, which is dependent on particle size, is demonstrated. The obtained results may be employed in the development of alternative methods of information processing in current and future information technologies.