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

Abstract

Grain growth, oxygen stoichiometry, and phase stability of nanostructurally stabilized cubic zirconia ͑NSZ͒ are investigated under 2 MeV Au-ion bombardment at 160 and 400 K to doses up to 35 displacements per atom ͑dpa͒. 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 irradiation dose to ϳ30 nm at ϳ35 dpa. Slower grain growth is observed under 400 K irradiations, as compared to 160 K irradiations, indicating that the grain growth is not thermally activated and irradiation-induced grain growth is the dominating mechanism. While the cubic structure is retained and no new phases are identified after the high-dose irradiations, oxygen reduction in the irradiated NSZ films is detected. The ratio of O to Zr decreases from ϳ2.0 for the as-deposited films to ϳ1.65 after irradiation to ϳ35 dpa. The loss of oxygen suggests a significant increase in oxygen vacancies in nanocrystalline zirconia under ion irradiation. The oxygen deficiency may be essential in stabilizing the cubic phase to larger grain sizes.

Comprehensive study of the effect of the irradiation temperature on the behavior of cubic zirconia

“…Moreover, YSZ exhibits a very high radiation resistance, suggesting potential use as an IMF. This radiation resistance has been demonstrated in a series of experimental studies where the irradiation environment has been simulated with external ion beams [5][6][7][8][9][10][11][12] or also via computational approaches. [13][14][15] All works put forward that YSZ maintains its structural integrity up to very high irradiation levels ($100 displacements per atom, dpa).…”

Lattice distortions and oxygen vacancies produced in Au+-irradiated nanocrystalline cubic zirconia

“…Recently, it has been demonstrated that it is possible to produce nanocrystalline tetragonal or cubic zirconia that is thermodynamically stable at atmospheric pressures without the addition of stabilizers [10,13,14], i.e. they are nanostructurally stabilized.…”

“…they are nanostructurally stabilized. Furthermore, the grain size of pure cubic nanostructurally stabilized zirconia (NSZ) films can be tailored by varying the ion dose during energetic, heavy ion irradiation [14]. Moreover, a significant loss of oxygen is also reported, suggesting the production of oxygen vacancies as a result of the irradiation [14].…”

“…Furthermore, the grain size of pure cubic nanostructurally stabilized zirconia (NSZ) films can be tailored by varying the ion dose during energetic, heavy ion irradiation [14]. Moreover, a significant loss of oxygen is also reported, suggesting the production of oxygen vacancies as a result of the irradiation [14]. Thus it may be possible to tailor the oxygen vacancy content, and hence the oxygen ion conductivity, in cubic NSZ by ion irradiation that could lead to much higher ionic conductivity than that obtained in dopantstabilized zirconia films, where the conductivity is often limited by the interactions between the oxygen vacancies and the stabilizing elements, as described previously.…”

The role of helium implantation induced vacancy defect on hardening of tungsten

“…IBI is a feasible and efficient tool to investigate the radiation damage in nuclear materials. [2][3][4][5] Helium ion implantation was used to simulate a particle irradiation effects on materials considered for applications in fusion reactors. [6][7][8] Because the surface erosion of tungsten is the major concern in the fusion reactors, high flux, high fluence, and low energy (hundred eV) helium implantation was performed into tungsten at temperatures above 400 C. 9,10 Recently, in order to investigate the early stage of helium irradiation effect on tungsten, Lhuillier et al 7 performed irradiation with He ions of relatively low flux, low fluence and analyzed the corresponding microstructure of tungsten.…”