title: Structures and the oxygen deficiency of tetragonal and monoclinic zirconium oxide nanoparticles.
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, two phases of tetragonal ZrO(2 - delta) (average particle size: 11 +/- 2 nm) and monoclinic ZrO2 (average particle size: 24 +/- 4 nm) existed, where the weight fractions were estimated to be 84.9 and 15.1 wt%, respectively. The structural refinement suggests that the tetragonal ZrO(2 - delta) has an oxygen deficiency [delta = 0.031 (7)] and that the monoclinic ZrO(2 - delta) has less oxygen deficiency (delta approximately 0), where delta is the vacancy concentration. The monoclinic ZrO2 has a larger unit-cell volume. The maximum-entropy method analysis indicated covalent bonding between Zr and O atoms.
authors.affiliation: Department of Materials Science and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8502, Japan. yashima@materia.titech.ac.jp
authors.forename: Masatomo
authors.initials: M
authors.lastname: Yashima
authors.forename: Shin
authors.initials: S
authors.lastname: Tsunekawa