 |
Secretaria:
Aptor
7encontro@sbpmat.org.br
|
Alexandra Navrotsky
Director, NEAT ORU
Edward Roessler Chair in Mathematical and Physical Sciences
Peter A Rock Thermochemistry Laboratory and NEAT ORU
University of California at Davis
One Shields Avenue, Davis, CA 95616
http://navrotsky.engr.ucdavis.edu
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 is a competition among polymorphism, 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 than 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.
|
 |
