Local Structures Surrounding Zr in Nanostructurally Stabilized Cubic Zirconia: Structural Origin of Phase Stability

Authors

Y. L. Soo, National Tsing Hua University, Hsinchu 30013, Taiwan
P. J. Chen, National Tsing Hua University, Hsinchu 30013, Taiwan
S. H. Huang, National Tsing Hua University, Hsinchu 30013, Taiwan
T. J. Shiu, National Tsing Hua University, Hsinchu 30013, Taiwan
T. Y. Tsai, National Tsing Hua University, Hsinchu 30013, Taiwan
Y. H. Chow, National Tsing Hua University, Hsinchu 30013, Taiwan
Y. C. Lin, National Tsing Hua University, Hsinchu 30013, Taiwan
S. C. Weng, National Tsing Hua University, Hsinchu 30013, Taiwan
S. L. Chang, National Tsing Hua University, Hsinchu 30013, Taiwan
G. Wang, University of Nebraska - Lincoln
Chin Li Cheung, University of Nebraska - LincolnFollow
Renat F. Sabirianov, University of Nebraska at OmahaFollow
Wai-Ning Mei, University of Nebraska at OmahaFollow
F. Namavar, University of Nebraska Medical Center, Omaha
H. Haider, University of Nebraska Medical Center, Omaha
K. L. Garvin, University of Nebraska Medical Center, Omaha
J. F. Lee, National Synchrotron Radiation Research Center, Hsinchu 30013, Taiwan
H. Y. Lee, Department of Chemistry, National Central University, Jhongli 32001, Taiwan
P. P. Chu, Department of Chemistry, National Central University, Jhongli 32001, Taiwan

Document Type

Article

Date of this Version

2008

Comments

Published in JOURNAL OF APPLIED PHYSICS 104, 113535 (2008). Copyright © 2008 American Institute of Physics. Used by permission.

Abstract

Local environment surrounding Zr atoms in the thin films of nanocrystalline zirconia (ZrO₂) has been investigated by using the extended x-ray absorption fine structure (EXAFS) technique. These films prepared by the ion beam assisted deposition exhibit long-range structural order of cubic phase and high hardness at room temperature without chemical stabilizers. The local structure around Zr probed by EXAFS indicates a cubic Zr sublattice with O atoms located on the nearest tetragonal sites with respect to the Zr central atoms, as well as highly disordered locations. Similar Zr local structure was also found in a ZrO₂ nanocrystal sample prepared by a sol-gel method. Variations in local structures due to thermal annealing were observed and analyzed. Most importantly, our x-ray results provide direct experimental evidence for the existence of oxygen vacancies arising from local disorder and distortion of the oxygen sublattice in nanocrystalline ZrO₂. These oxygen vacancies are regarded as the essential stabilizing factor for the nanostructurally stabilized cubic zirconia.