The formation of a new phase in nanoparticles

First-order phase transitions in nanoparticles (e.g., metal hydride formation) occur via absorption of species from or release to the gas or liquid phase. If the lattice strain is negligible, the uptake corresponding to a new phase exhibits a stepwise rise or drop with increasing or decreasing pressure or chemical potential of the absorbed species. With decreasing nanoparticle size, L, and increasing role of the surface and subsurface layers, this feature becomes less manifested because the system is less ideal. We present 3D lattice Monte Carlo simulations, explicitly illustrating this effect for L in the range from 100 down to 10 (L is measured in units of lattice spacing).