Phase stabilization in nitrogen-implanted nanocrystalline cubic zirconia

Abstract

The phase stability of nanocrystallites with metastable crystal structures under ambient conditions is usually attributed to their small grain size. It remains a challenging problem to maintain such phase integrity of these nanomaterials when their crystallite sizes become larger. Here we report an experimental-modelling approach to study the roles of nitrogen dopants in the formation and stabilization of cubic ZrO(2) nanocrystalline films. Mixed nitrogen and argon ion beam assisted deposition (IBAD) was applied to produce nitrogen-implanted cubic ZrO(2) nanocrystallites with grain sizes of 8-13 nm. Upon thermal annealing, the atomic structure of these ZrO(2) films was observed to evolve from a cubic phase, to a tetragonal phase and then a monoclinic phase. Our X-ray absorption near edge structure study on the annealed samples together with first-principle modelling revealed the significance of the interstitial nitrogen in the phase stabilization of nitrogen implanted cubic ZrO(2) crystallites via the soft mode hardening mechanism.

Raman spectra analysis of ZrO2 thermally grown on Zircaloy substrates irradiated with heavy ion: Effects of oxygen isotopic substitution

“…Second, in the case of a strong disorder, the reduced Raman spectra ultimately represent the frequency distribution of the phonon density of states (VDOS). In the present case, the observed broad signal has an apparent cut‐off wavenumber at about 830 cm −1 , which matches the cut‐off frequencies of the m‐ZrO 2 , t‐ZrO 2 , and even c‐ZrO 2 polymorphs calculated VDOS . Thus, it is tempting to interpret these spectra in terms of disorder.…”

Oxygen vacancy mediated cubic phase stabilization at room temperature in pure nano-crystalline zirconia films: a combined experimental and first-principles based investigation

“…However, since zirconia is not inherently stable in the cubic phase at room temperature, the application of zirconia crucially depends on the stabilization of the cubic phase at room temperature. This is generally achieved by the addition of lower valence stabilizer oxides, such as Y2O3, MgO etc., which creates oxygen vacancies (in the zirconia structure) to energetically favor the cubic phase [14][15][16]. Using this method, cubic zirconia is normally obtained by the addition of 8 to 20 mol% of these stabilizer oxides [14,15].…”

Comparison of peri-implant bone formation around injection-molded and machined surface zirconia implants in rabbit tibiae

“…The fabrication or modification of a dense, hard zirconia surface is not so easy to achieve sufficient roughness 34) . A number of approaches are currently used to increase the surface roughness of machined zirconia to enhance the peri-implant bone response such as sandblasting 35,36) , coating 24,37,38) , acid or alkali etching 26,39,40) , laser treatment 8) , and UV irradiation 41) .…”