Crystal structure and oxygen deficiency of zirconium-oxide nano particles

Abstract

The crystal structure of zirconium oxide nanoparticles was refined by the Rietveld analysis of synchrotron X-ray powder diffraction data measured at 298 K. In the nanoparticles, there existed two phases of tetragonal ZrO_2-d (average particle size: 11+-2 nm) and monoclinic ZrO₂ (average particle size: 24+-4 nm) where the weight fractions were estimated to be 84.9 and 15.1 wt%, respectively. The structural refinement suggests that the tetragonal ZrO_2-d has oxygen deficiency (d=0.031(7)) and that the monoclinic ZrO_2-d has less oxygen deficiency (d=0), where the d is the vacancy concentration. The monoclinic ZrO2 has a larger unit-cell volume.