"Energetics of Oxide Nanomaterials"

Extensive calorimetric studies of oxide nanoparticles over the past several years in our laboratory have established systematic trends in energetics at the nanoscale. There iiiis a competition among polymorpism, surface energies and hydration that leads to crossover in phase stability at the nanoscale. Metastable polymorphs have lower surface energies than stable ones. Oxyhydroxides have lower surface energies that anhydrous oxides. Hydration stabilizes the surface. These trends are illustrated with data for aluminum oxides, iron oxides, titania, and zinc oxide. For ZnO, nanoneedles are shown to have the highest surface energy, nanorods intermediate, and nanoparticles the smallest. A comparison, based on very recent calorimetric data, of surface and interfacial energies for yttria stabilized zirconia, is presented.

Zinc oxide nanoparticles with different morphologies have different surface energies.