Modelling the effect of particle shape on the phase stability of ZrO2 nanoparticles

At the nanoscale, zirconium dioxide may form in a number of different polymorphs, depending in part upon the size of the particles. Although considerable attention has been given to finding methods for controlling the phase of zirconium dioxide nanocrystals, the role of nanomorphology in affecting the size-dependent phase transition has been largely ignored. To address this issue, we have used a shape-dependent thermodynamic model to investigate the relationship between nanomorphology and phase stability. Our results provide the free energy of formation for tetragonal and monoclinic nanocrystals with a variety of shapes, and show that the transition size is strongly dependent on the prevalence of particular surface facets. From these results we suggest that variations in the thermochemical results reported in the literature may also be partially attributed to variations in nanocrystal shapes.