November 10, 2010
Journal Article

Grain growth and phase stability of nanocrystalline cubic zirconia under ion irradiation

Abstract

Grain growth, oxygen stoichiometry and phase stability of nanostructurally-stabilized zirconia (NSZ) in pure cubic phase are investigated under 2 MeV Au ion bombardment at 160 and 400 K to doses up to 35 displacements per atom (dpa). The NSZ films are produced by ion-beam-assisted deposition technique at room temperature with an average grain size of 7.7 nm. The grain size increases with dose, and follows a power law (n=6) to a saturation value of ~30 nm that decreases with temperature. Slower grain growth is observed under 400 K irradiations, as compared to 160 K irradiations, indicating that thermal grain growth is not activated and defect-stimulated grain growth is the dominating mechanism. While cubic phase is perfectly retained and no new phases are identified after the high-dose irradiations, reduction of oxygen in the irradiated NSZ films is detected. The ratio of O to Zr decreases from ~2.0 for the as-deposited films to ~1.65 after irradiation to ~35 dpa. Significant increase of oxygen vacancies in nanocrystalline zirconia suggests substantially enhanced oxygen diffusion under ion irradiation, a materials behavior far from equilibrium. The oxygen deficiency may be essential in stabilizing cubic phase to larger grain sizes.

Revised: July 25, 2020 | Published: November 10, 2010

Citation

Zhang Y., W. Jiang, C.M. Wang, F. Namavar, P.D. Edmondson, Z. Zhu, and F. Gao, et al. 2010. Grain growth and phase stability of nanocrystalline cubic zirconia under ion irradiation. Physical Review B 82, no. 18:184105:1-7. PNNL-SA-75087. doi:10.1103/PhysRevB.82.184105