Tracer diffusion studies in NiO bicrystals and polycrystals

Grain Boundary Diffusion in Ceramics

“…In extensive measurements using NiO bicrystals, however, preferential diffusion of Co along the boundaries was not detected thus implying diffusivities lower by several orders of magnitude than those reported for polycrystalline NiO formed by oxidation of Ni. The reasons for this difference are not clear, but other experiments using bicrystals and sintered polycrystals of NiO have also given erratic results [20,21].…”

“…Attempts have been made to study Ni diffusion in NiO bicrystals [20] and polycrystalline specimens produced by sintering [21) using autoradiography.…”

Redox stability of SOFC: Thermal analysis of Ni–YSZ composites

“…In NiO, the diffusion of Ni cations is several orders of magnitude faster than O anions, therefore the outward lattice diffusion of Ni is the dominating mechanism at high temperatures (above about 1000°C). When reducing the temperature, the grain boundary diffusion of Ni becomes of increasing importance as reported by Atkinson [13][14][15]. The parabolic rate constant can be assessed from diffusion data as [11] k p = 6:…”

High‐Temperature Oxidation

“…Conversely, the contribution made by short-circuit diffusion processes will be negligible at higher temperatures. Grain boundary diffusion in growing oxide scales has been reported for NiO [88,89], Cr 2 O 3 [90], Al 2 O 3 [91], and other product films.…”