Origin of Structural Stability in Cubic ZrO2 Nanocrystals Studied by EXAFS*

Local environments surrounding Zr nanocrystalline powders and thin films of cubic zirconia prepared by sol-gel and ion beam assisted deposition (IBAD) methods were investigated by using extended x-ray absorption fine structure (EXAFS) technique. These materials have shown cubic long-range-order structure and high hardness without chemical stabilizers. To understand the origin of structural stability, the short-range-order local structural information obtained from EXAFS measurements is of central importance. Powder samples with different nanoparticle sizes prepared by different sol-gel processes were analyzed. Zr k-edge EXAFS, as well as N K-edge x-ray absorption near-edge structures (XANES), will also be presented to demonstrate the evolution of O vacancies and possible N impurities due to thermal annealing in the IBAD deposited films.