%0 Journal Article
%A Mueller, Michael P.
%A Pingen, Katrin
%A Hardtdegen, Alexander
%A Aussen, Stephan
%A Kindsmueller, Andreas
%A Hoffmann-Eifert, Susanne
%A De Souza, Roger A.
%T Cation diffusion in polycrystalline thin films of monoclinic HfO 2 deposited by atomic layer deposition
%J APL materials
%V 8
%N 8
%@ 2166-532X
%C Melville, NY
%I AIP Publ.
%M FZJ-2020-03003
%P 081104 -
%D 2020
%X Though present in small amounts and migrating at low rates, intrinsic cation defects play a central role in governing the operational lifetime of oxide-ion conducting materials through slow degradation processes such as interdiffusion, kinetic demixing, grain growth, and creep. In this study, a new experimental approach to characterizing the behavior of such slow-moving, minority defects is presented. Diffusion is probed in samples with a constant cation-defect concentration well above the equilibrium values. This approach is applied to monoclinic hafnium dioxide, m-HfO2. To this end, nanocrystalline thin films of m-HfO2 were prepared by atomic layer deposition. Diffusion experiments with ZrO2 as a diffusion source were performed in the temperature range 1173 ≤ T/K ≤ 1323 in air. The Zr diffusion profiles obtained subsequently by secondary ion mass spectrometry exhibited the following two features: the first feature was attributed to slow bulk diffusion and the second was attributed to combined fast grain-boundary diffusion and slow bulk diffusion. The activation enthalpy of Zr diffusion in bulk HfO2 was found to be (2.1 ± 0.2) eV. This result is consistent with the density-functional-theory calculations of hafnium-vacancy migration in m-HfO2, which yield values of ∼2 eV for a specific path. The activation enthalpy of the grain-boundary diffusion of (2.1 ± 0.3) eV is equal to that for bulk diffusion. This behavior is interpreted in terms of enhanced cation diffusion along space-charge layers
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000560032100002
%R 10.1063/5.0013965
%U https://juser.fz-juelich.de/record/878685