Diffusion in doped and undoped amorphous zirconia

Molecular dynamics study of oxygen-ion diffusion in yttria-stabilized zirconia grain boundaries

“…Further total RDF after 4 Å as well as partial RDF of O–O, O–Zr, O–Y showed no significant long range structure, as reported in other theoretical studies of amorphous YSZ. 63–65 However, in this work we did not achieve the solid solution as expected for amorphous structures, instead we have a short range disordered structure after amorphization step, needed to recrystallize the system. 64,65 The broader peaks observed along r (Å) for the amorphous structure and the sharp peaks observed for the recrystallized structure clearly show the success of the A&R process.…”

Lithium Stabilization of Amorphous Zro2

“…It was found that the segregated Li after crystallisation was highly soluble in water. When combined with simulation work indicating that lithium can increase vacant oxygen concentrations and increase oxygen diffusion (Owen et al, 2021;Stephens et al, 2023), this experimental work provides additional potential to understand the accelerated corrosion of zirconium alloys in the presence of Li and opens a range of investigative avenues that may be explored. In-situ XPS may be used to identify the form lithium takes once segregated from grain boundaries during crystallisation.…”

“…This might promote oxide grain nucleation over growth, so does not get the preferential columnar growth in the monoclinic oxide grains that are indicative of a more protective oxide in non-accelerated water-grown oxide films (Pêcheur et al, 2000(Pêcheur et al, , 2009Yankova et al, 2023). It is also possible that Li promotes grain boundaries that are undercoordinated in oxygen and allow a path for oxygen to "hop" to the metal surface (Owen et al, 2021). This indicates that a high oxygen vacancy concentration may produce a high oxygen flux through the grain boundaries.…”

“…Amorphous structures can be expected to form more readily at lower temperatures due to limited kinetic energy availability for crystalline atomic orientations (below 450 • C (Lebeau et al, 2020)). Further atomic scale simulation work has been undertaken to assess transport mechanisms of lanthanide dopants through the disordered oxide grain boundary (Owen et al, 2021) Recent atomistic modelling has identified an indication of Li solution in the amorphous structures coupled with an associated increase of vacant oxygen defects as a result (Stephens et al, 2023).…”

“…This investigation prepared and characterised amorphous oxides with different Li levels to support the simulations and provide extra insight into the behaviour of the surrogate grain boundary material. It also looked at the impact of Li stabilizing an amorphous structure, analogous to a highly complex grain boundary, which have been found through simulation to potentially modify grain boundary mobility of corrosive species (Owen et al, 2021;Stephens et al, 2023).…”