Nanoparticles versus bulk materials: dramatic changes of ZrO₂ properties by nanostructuring

Materials in form of nanoparticles or clusters exhibit rather different properties compared to their bulk counterparts. This has been widely shown in the case of metals. Much less is known in the field of oxides. Here we report the results of first principles calculations on nanoparticles of ZrO₂ containing from a few tens to a few hundred of atoms. Zirconia is widely used in many technological applications for its wide gap, non-reducibility, low defects concentration, non-magnetic behaviour. We demonstrate that ZrO₂ in form of stoichiometric nanoparticles exhibits completely different properties: it becomes easily reducible (by oxygen removal or H₂ treatment), highly reactive (with charge transfer to supported metal species) and it turns from a non-magnetic material to a stable ferromagnet at room temperature. These results show the importance of preparing traditional materials in form of nm size particles to obtain new and unprecedented physical properties.