Supporting Information

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1 Supporting Information Dislocations Accelerate Oxygen Ion Diffusion in La 0.8 Sr 0.2 MnO 3 Epitaxial Thin Films Edvinas Navickas 1, Yan Chen 2χ, Qiyang Lu 3, Wolfgang Wallisch 4, Tobias M. Huber 1,2,3,5,6, Johannes Bernardi 4, Michael Stöger-Pollach 4, Gernot Friedbacher 1, Herbert Hutter 1, Bilge Yildiz 2,3* and Jürgen Fleig 1* 1 Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, Vienna, A-1060, Austria 2 Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, , Cambridge, MA 02139, USA 3 Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, , Cambridge, MA 02139, USA 4 University Service Centre for Transmission Electron Microscopy, Vienna University of Technology, Wiedner Hauptstr. 8-10, Vienna A-1040, Austria 5 Next-Generation Fuel Cell Research Center (NEXT-FC), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka , Japan 6 International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka , Japan *corresponding authors: byildiz@mit.edu, J.Fleig@tuwien.ac.at χ current affiliation: New Energy Institute, School of Environment and Energy, South China University of Technology, 382 East Road, University City, Guangzhou P.R. China S1

2 AFM measurements Figure S1. Surface topography measured by AFM on LSM/STO (a) and LSM/LAO (b) samples and in both cases thicker layers show a rougher surface. Even the thinnest layers (10 nm) show an island like thin films growth topography which indicates due to the limited surface diffusion. S2

3 TEM image analysis Figure S2. TEM images of LSM thin films formed on LAO (a and b). The lattice parameter c perpendicular to the LSM/LAO interface was estimated from high resolution (HR) TEM image. The distribution of atomic planes was estimated in coloured parts of the HRTEM image. c) The distributions of atomic plane in the colored regions are shown and indicate that the lattice parameter c in LSM/LAO is slightly decreasing towards the interface. d) and e) TEM images of LSM thin films formed on STO substrates indicating epitaxial growth. S3

4 Figure S3. TEM high resolution (HRTEM), bright (BF) and dark (DF) field images of LSM layers on LAO substrate: a) 10 nm (HRTEM); b) 87 nm (DF TEM); c) 87 nm (HRTEM); d) 40 nm (BF TEM); e) 40 nm (HRTEM); f) 126 nm (BF TEM). Due to the observed vertical fringes in TEM images on LSM/LAO samples, the high resolution TEM image (Figure S4a) was analyzed by geometric phase analysis (GPA) 1-2. In this method a Gaussian mask was centered separately on two strong reflections in the Fourier transform (FT) (Figure S4b) of the HRTEM image and inverse FTs were performed. The phase component of the inverse FT of the red marked Bragg spot suggests some irregularities of the lattice fringes as shown in Figure S4c. The strain mapping in x direction (ε xx ) of the HRTEM image exhibits no specific details on expansion or compression (Figure S4d). In contrast, the ε yy strain (Figure S4e) presents the same perpendicular feature as in the HRTEM image and on the left side of this feature there are some structural irregularities starting from it. On the other hand, it also confirms that the structure is the same on both sides of the observed vertical fringe. S4

5 Figure S4. GPA analysis of a high resolution TEM image of the LSM layer on LAO substrate: a) HRTEM image at the proximity of observed vertical feature in LSM layer on LAO substrate; b) Fourier transform (FT) of the HRTEM image; c) phase image of the red Bragg spot from the FT image; d) ε xx strain, e) ε yy strain and f) ε xy strain were analysed from the marked spots of the FT image. S5

6 Fitting of isotope exchange depth profiles in LSM/STO The detailed analysis of LSM/STO films revealed that also there are some deviations from a profile with only one diffusion process as shown in Figure S5a and b. The depth profiles of thin LSM layers can be approximated by an error function (Figure S5a) while the isotope exchange profiles in thicker layers also contain a second diffusion mechanism (Figure S5b). However, the effects are much less pronounced than for LSM on LAO. Similar results were also obtained in epitaxial LSM on STO substrates in a previous publication 3. Figure S5. Experimental isotope exchange depth profiles in 10 nm (a) and 140 nm (b) LSM/STO samples fitted by an error function. S6

7 Temperature effect Tracer profiles were measured for 40 nm LSM on LAO and STO substrates in a temperature range from 400 C to 800 C. All profiles with fitted bulk part are shown in Figure S6a. Measurements at low temperatures show only one diffusion process. At 500 C a second diffusion process appears. The D b and k b obtained from the fitting are shown in Arrhenius plot (Figure S6b) together with the values from a previous publication 3 ; both are in a good agreement. However, analysis of the dislocation related profile part is only possible in a narrow temperature range. Figure S6. a) Tracer profiles obtained at different temperatures for LSM on STO and LAO. b) Arrhenius plot of bulk diffusion D b and surface exchange k b coefficients obtained from LSM/LAO and LSM/STO. The results from a previous study on LSM/STO are also included 3. S7

8 Analysis of isotope exchange depth profiles in LSM/LAO Effect of k d, δ and D d on isotope diffusion profiles. The simulations in Figure S7 indicate that variations of dislocation density (=1/(2m)) or exchange coefficient k d affect the profiles in a similar manner. For constant D d both do hardly affect the slope of the profile but change the absolute tracer value in the dislocation related curve part. Any variation of the oxygen isotope level may thus either come from a variation in δ (Figure S7a) or from a variation in k d (Figure S7b) Owing to the similar effect of dislocation exchange coefficient and dislocation density, exact values of k d and cannot be obtained from the presented data analysis and the same k d value was used for all fits of measured curves. However, while higher dislocation densities always increase the tracer fraction, there is an upper limit of the tracer fraction for k d variations (D b limited case in Figure S7b). The variation of the isotope depth profile slope is governed by the oxygen diffusion coefficient through dislocations (D d ), as it is shown in Figure 7c. S8

9 Figure S7. (a) The tracer profile in 126 nm LSM/LAO was modelled with different dislocation densities while keeping k d constant ( m s -1 ). Absolute tracer fractions strongly depend on while slopes hardly change (D d = m s -2 ). b) A similar effect is found for the dislocation surface exchange coefficient k d.. The values of k d and δ thus define the level of isotope concentration in the material, while the dislocation oxygen diffusion coefficient determines the slope of IED profiles. This is illustrated for = cm -1 and k d = m s -1 (c). S9

10 References 1. Hÿtch, M. J.; Snoeck, E.; Kilaas, R., Quantitative Measurement of Displacement and Strain Fields from HREM Micrographs. Ultramicroscopy 1998, 74, Peters, J. J. P.; Beanland, R.; Alexe, M.; Cockburn, J. W.; Revin, D. G.; Zhang, S. Y.; Sanchez, A. M., Artefacts in Geometric Phase Analysis of Compound Materials. Ultramicroscopy 2015, 157, Navickas, E.; Huber, T. M.; Chen, Y.; Hetaba, W.; Holzlechner, G.; Rupp, G.; Stoger-Pollach, M.; Friedbacher, G.; Hutter, H.; Yildiz, B.; Fleig, J., Fast Oxygen Exchange and Diffusion Kinetics of Grain Boundaries in Sr-Doped LaMnO 3 Thin Films. Phys. Chem. Chem. Phys. 2015, 17, S10