Gd-doped Ceria Research Articles

Characterization of a Laser-Based Heating System Coupled With In Operando Raman Spectroscopy for Studying Solar Thermochemical Redox Cycles

A 200 W CO2 laser-based heating system coupled with in operando Raman spectroscopy has been developed. The system delivers highly concentrated radiation capable of driving thermochemical reactions and simulates heat fluxes expected by 3D solar concentrating systems. 10 mol% Gd-doped and pure ceria pellets were prepared and used to characterize the system because of their well-established thermodynamic and kinetic properties, as well as their strong Raman peak due to F2 g symmetrical mode at 460 cm−1. Reduction in an H2 atmosphere has been carried out to investigate the behavior of the full width at half maximum (FWHM) of the F2 g Raman peak resulting from changes in temperature and oxidation state. For both samples, an increase in temperature during heating in air (i.e., fully oxidized) resulted in a peak shift toward low wavenumber and an increase of FWHM. The FWHM versus temperature curves were then measured for controlled reduction extents ranging between sample averaged nonstoichiometries of δ = 0–0.209 as a function of temperature. At a fixed temperature, Gd-doped ceria exhibited an increase in FWHM with increasing reduction extent until δ = 0.056. At greater reduction extents, the FWHM decreased with increasing reduction extents. We attribute this to changes in the lattice parameter caused by the eventual formation of intermediate cubic Ce2O3 at the radiated surface. This study demonstrates the promise of utilizing Raman spectroscopy to probe thermochemical reactions in operando. Going forward, we expect that this will be an especially promising tool for characterizing emerging thermochemical materials with complex phase equilibria, especially for nonequilibrium processes.

The Impact of Fe Addition on the Electronic Conductivity of Gadolinium Doped Ceria

Gd-doped ceria with transition metal oxide co-doping is especially interesting for catalytical applications in the intermediate temperature range between 400–600°C. Ce0.9-xFexGd0.1O2-δ samples with x = 0.0 to 0.05 were produced via a sol-gel synthesis route. XRD measurements proved the materials to be single phase with fluorite structure, but electron microscopy investigations showed enrichment of Gd and Fe at the grain boundaries and the existence of small-scale secondary phases for 5 mol% Fe. The effect of Fe co-doping on the ionic and electronic conductivity was monitored using impedance spectroscopy and DC polarization-relaxation measurements applying ion blocking micro contacts (Hebb-Wagner setup). Already the addition of 1 mol% Fe raised the total conductivity of the material by two decades (about 10−4 S/cm at 750°C compared to 5·10−6 S/cm for Ce0.9Gd0.1O2-δ). In addition, already for 1 mol% Fe, but very clearly for 2 and 5 mol% Fe addition, a temperature and oxygen partial pressure dependent maximum in the p-type conductivity has been found, which is attributed to the Fe2+/3+ redox reaction and a related small polaron hopping process.

Retraction: Assessment of the Effect of Transition Metal Oxide Addition on the Conductivity of Commercial Gd-Doped Ceria [J. Electrochem. Soc., 165, F533 (2018)

Retraction: Assessment of the Effect of Transition Metal Oxide Addition on the Conductivity of Commercial Gd-Doped Ceria [J. Electrochem. Soc., 165, F533 (2018)

Built-in bias in Gd-doped ceria films and its implication for electromechanical actuation devices

Electromechanical response of 1.5 μm thick 2 mm diameter self-supported films (membranes) of 20 mol% Gd-doped ceria with Ti electrodes was measured at two temperatures (25 and 75 °C) as a function of direct (UDC) and alternating (UAC, 20 Hz) voltages. The films assumed a soup-panbowl shape and application of the external voltage resulted in a uniform vertical shift of the flat area. In the absence of superimposed UDC, UAC induces electromechanical response at the 1st and 2nd harmonics at both temperatures. The amplitude of the 2nd harmonic is proportional to UAC2 at these temperatures and it is independent of UDC, which identifies it as due to the electrostriction effect. Direct measurement of the built-in bias via minimization of the 1st harmonic response, as well as electrical impedance and IV measurements indicate that, although asymmetry of the contacts may contribute to the appearance of the 1st harmonic, it is insufficient to explain it. Based on the fact that the force-displacement curve of the membrane measured with AFM is hysteretic, we hypothesize that the 1st harmonic response is related to the non-linear mechanical deformation of the buckled film.

NiO-GDC10/GDC10/LSCF-GDC10 Manufactured By Tape Casting and Reactive Magnetron Sputtering Processes of Solid Oxide Fuel Cells

We developed a cost–effective a method to manufacture performance planar solid oxide fuel cells using composite electrode by tape casting and electrolyte by reactive magnetron sputtering. NiO and GDC (10% Gd), used for the anode-supported (as) and the anode functional layer (afl) powders were milled by using zirconia balls in a Turbula-(System Schatz from WAB) times up to 24 hours. Half-cell, 28 mm of diameter, Ni-GDC composite anodes have been fabricated by slurry based tape casting (Elcometer4340 Automatic Film Applicator) method for anode supported solid oxide fuel cell. Depending on the results, work on the support anode (AS) Ni0-GDC will continue in particular to avoid the presence of the residual phase of carbon resulting from the use of an agent poro formers with graphite . The decomposition of organic additives and the shrinkage of green tape is analyzed thermo-gravimetric and differential thermal analysis (TG) of anode. PVD by plasma emission monitoring (PEM) was employed to synthesize GDC (10%Gd doped ceria) thin films on anode-grade ceramic substrate (porous NiO-GDC10). An Alcatel SCM650 sputtering chamber was used for synthesizing the dense GDC layers. A Ce-Gd metallic target (90-10% at) was powered by a pinnacle + pulsed current generator from Advanced Energy under reactive atmosphere.The cathode, which is made of (LSCF-GDC10) was screen printed onto electrolyte film and sintered to form a complete SOFC. The obtained cell after sintering was seen without any deformation or crack. Pycnometry and porosimetry techniques were primarily used to determine pore size and pore volume by equation Washburn and Ideal gas law-method and the decomposition of organic additives and the shrinkage of green tape was analyzed thermo-gravimetric of NiO-GDC10 and LSCF-GDC10. The microstructural morphological surface features of the cell was by 3D profilometry and complete cell were analyzed by Scanning Electron Microscopy (SEM), XRD and was employed to nos-destructively quantify the craking and behavior observed before and after different annealing. The measurements will be carried out on a complete cell with the measuring bench of the company Fiaxell of 5*5 cm2 and on a cell of 28 mm of diameter in order to obtain curves I / V.

Accelerated Phase Transition of Pr2NiO4 in the Presence of GDC Interlayer

Praseodymium Nickelate (Pr2NiO4) has the potential to be a cathode for commercial solid oxide fuel cells (SOFCs) due to its high activity towards oxygen reduction. However, when Gd-doped Ceria (GDC) is used as an interlayer to prevent cathode-electrolyte interaction, phase transitions in Pr2NiO4 are accelerated. The accelerated phase transition in Pr2NiO4 decreases the stability of the cell, leading to faster degradation rates in performance over the lifetime of the cell. Identifying how the GDC interlayer affects phase transition will increase the effectiveness of Pr2NiO4 as an SOFC cathode. In this work, the accelerated phase transition of Pr2NiO4 in the presence of GDC will be investigated by: (1) thermo-annealing mixtures of Pr2NiO4/GDC powders at varying compositions and temperatures and, (2) constructing and analyzing cells with Pr2NiO4-GDC composite electrodes and GDC interlayers. XRD will be used to analyze the resulting phase transitions of the annealed powders and of the operated cells. Identifying structural and operational dependencies of this mechanism may help us develop approaches to increase the long-term stability of SOFCs with Pr2NiO4 as cathode material. Keywords: Nickelate, Doped ceria, phase transition, solid oxide fuel cell

Frequency-Resolved Evaluation of Electrode Oxidation State in La0.6Sr0.4CoO3 Thin Films with Operando XAS

Commercial adoption and implementation of renewable, but intermittent, energy sources relies on a new generation of high-performance energy conversion and storage devices, such as solid oxide fuel cells (SOFC) and solid oxide electrolysis cells (SOEC). Performance of the oxygen electrode in SOFC is a limiting factor; however, improvements are hindered by inadequate understanding of electrochemical reaction and ionic diffusion processes. AC impedance and DC polarization techniques are typically used to infer relationships between driving energy and reaction rate, but uniquely understanding reaction mechanisms without direct chemical state measurements of the electrode is challenging. In recent years, workers have developed in operando X-ray absorption spectroscopy (XAS) to study oxygen chemical potentials in SOFC cathodes under operating temperatures and Po2. Determining the oxygen chemical potential is based on shifts in the X-ray absorption edge of 3d transition metals due to valence changes to compensate for oxygen vacancies. So far, operando XAS has only been measured under DC polarization, and thus lacked the ability to probe processes of different timescales [1]. In this work, we extend operando XAS to AC impedance measurements, allowing direct frequency-resolved measurement of electrode oxidation state. This approach can potentially be applied to nonlinear harmonic responses, and the first step in the spatially-resolved mapping of the local steady-periodic electrode response. A dense film of La0.6Sr0.4CoO3 (LSC) was deposited on a mirror polished Gd-doped ceria pellet by pulsed laser deposition as the working electrode with porous Pt counter and reference electrodes. Absorption spectra of the Co K-­edge were collected from fluorescent X-rays to determine the detection energy most sensitive to changes in Co valence state. Operando XAS measurements were conducted at 973 K in 10% O2 at the predetermined X-ray energy, typically around 7.718 keV, under electrical perturbations large enough to excite moderate nonlinearity. The frequency resolved oxidation state response of the electrode is obtained by converting X-ray absorption data to oxygen chemical potentials via sets of calibration XAS spectra at various effective Po2. As a result, the data can be treated by the same analysis methods developed for the voltage response in AC impedance measurements.

Zero Degradation in Power Density over Long-Term SOFC Operation Based on a Novel Interlayer

Doped ceria interlayer is ubiquitously used between the cathode and electrolyte in solid oxide fuel cells to prevent the cathode/electrolyte interaction and offer a better thermal expansion match. The mechanism on how the interlayer influences the durability and activity of the cathode still remains elusive. This is particularly true in the nickelate cathode (e.g. Pr2NiO4) since the nickelate does go through a phase transition during operation. Traditional Gd-doped ceria was found to substantially accelerate the phase transition in Pr2NiO4 cathode, leading to faster cell degradation in performance. In this work, several new designs of the interlayer are adopted, including various approaches to add Pr into ceria. The addition of Pr in the ceria layer can suppress the phase decomposition of nickelate cathode and increase the performance. As a result, the cell performance exhibits zero degradation over 500 hours. Electrochemical impedance spectroscopy data and its distribution of relation times were obtained to understand the mechanism for this unique observation. Key words: Doped ceria, interlayer, zero degradation, nickelate

Anelastic and Electromechanical Properties of Doped and Reduced Ceria.

Room-temperature mechanical properties of thin films and ceramics of doped and undoped ceria are reviewed with an emphasis on the anelastic behavior of the material. Notably, the unrelaxed Young's modulus of Gd-doped ceria ceramics measured by ultrasonic pulse-echo techniques is >200 GPa, while the relaxed biaxial modulus, calculated from the stress/strain ratio of thin films, is ≈10 times smaller. Oxygen-deficient ceria exhibits a number of anelastic effects, such as hysteresis of the lattice parameter, strain-dependent Poisson's ratio, room-temperature creep, and nonclassical electrostriction. Methods of measuring these properties are discussed, as well as the applicability of Raman spectroscopy for evaluating strain in thin films of Gd-doped ceria. Special attention is paid to detection of the time dependence of anelastic effects. Both the practical advantages and disadvantages of anelasticity on the design and stability of microscopic devices dependent on ceria thin films are discussed, and methods of mitigating the latter are suggested, with the aim of providing a cautionary note for materials scientists and engineers designing devices containing thin films or bulk ceria, as well as providing data-based constraints for theoreticians who are involved in modeling of the unusual electrical and electromechanical properties of undoped and doped ceria.

Sulfur poisoning behavior of La1-xSrxCo1-yFeyO3-δ thin films with different compositions

Sulfur in the air stream is one of the primary contaminants affecting the stability of cathodes in solid oxide fuel cells (SOFCs). In this work, sulfur poisoning of La1-xSrxCo1-yFeyO3-δ (LSCF) thin films with different compositions was investigated. The composition of the cathode was systematically controlled by preparing La0.75Sr0.42Co0.15Fe0.68O3-δ (A-site excess LSCF) and La0.60Sr0.39Co0.20Fe0.81O3-δ (stoichiometric LSCF) thin films on Gd-doped ceria (GDC) substrates by pulsed laser deposition. The LSCF films were then heat-treated at 800 °C for 100 h in synthetic air with a trace amount of SO2 (ppb level). As an informative complement to the microstructural and compositional analyses, secondary ion mass spectrometry was also performed to effectively determine the extent of sulfur accumulations from LSCF cathode surface to GDC. The results showed that sulfur poisoning behavior of LSCF cathodes depends strongly on composition. The A-site excess LSCF films exhibited significant SrSO4 formation with severe porosity, whereas, only an isolated SrSO4 formation was observed in the stoichiometric LSCF films; instead, the partial poisoning by sulfur minimizes excessive porosity while enhancing Co-rich oxide precipitation. Electrochemical impedance spectroscopy was carried out to further elucidate the influence of cathode composition on cell stability. Thermodynamic considerations have been made to clarify the plausible chemical reaction mechanism between LSCF of different compositions with SO2.

Improved Phase Stability and CO2 Poisoning Robustness of Y-Doped Ba0.5Sr0.5Co0.8Fe0.2O3−δ SOFC Cathodes at Intermediate Temperatures

The outstanding oxygen permeability of the perovskite Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) and its applicability as a cathode in solid oxide fuel cells are remarkable, yet have been hindered by the formation of secondary phases at T < 840 °C and the subsequent degradation. The other main drawback to BSCF is related to the formation of carbonates in the presence of CO2. These degrade its excellent oxygen surface-exchange kinetics. In this work, 10% Y-doped Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF10Y) is electrochemically, microstructurally, and chemically characterized in O2- and CO2-containing atmospheres as porous cathodes in symmetrical cells with Gd-doped ceria as electrolyte. Experiments in oxygen/nitrogen gas mixtures (pO2 = 0.02–0.40 atm) at T = 600–900 °C showed high performance with a cathode specific resistance of 49.9 mΩ cm2 at 600 °C in air (pO2 = 0.21 atm), which is very comparable to 47.8 mΩ cm2 for undoped BSCF, but which deteriorates constantly under the same conditions. Moreover, adding significant amoun...

Hydrogen production through dry reforming of biogas using a porous electrochemical cell: Effects of a cobalt catalyst in the electrode and mixing of air with biogas

This paper reports the performance of porous Gd-doped ceria (GDC) electrochemical cells with Co metal in both electrodes (cell No. 1) and with Ni metal in the cathode and Co metal in the anode (cell No. 2) for CO2 decomposition, CH4 decomposition, and the dry reforming reaction of a biogas with CO2 gas (CH4 + CO2 → 2H2 + 2CO) or with O2 gas in air (3CH4 + 1.875CO2 + 1.314O2 → 6H2 + 4.875CO + 0.7515O2). GDC cell No. 1 produced H2 gas at formation rates of 0.055 and 0.33 mL-H2/(min m2-electrode) per 1 mL-supplied gas/(min m2-electrode) at 600 °C and 800 °C, respectively, by the reforming of the biogas with CO2 gas. Similarly, cell No. 2 produced H2 gas at formation rates of 0.40 mL-H2/(min m2) per 1 mL-supplied gas/(min m2) at 800 °C from a mixture of biogas and CO2 gas. The dry reforming of a real biogas with CO2 or O2 gas at 800 °C proceeded thermodynamically over the Co or Ni metal catalyst in the cathode of the porous GDC cell. Faraday's law controlled the dry reforming rate of the biogas at 600 °C in cell No. 2. This paper also clarifies the influence of carbon deposition, which originates from CH4 pyrolysis (CH4 → C + 2H2) and disproportionation of CO gas (2CO → C + CO2), on the cell performance during dry reforming. The dry reforming of a biogas with O2 molecules from air exhibits high durability because of the oxidation of the deposited carbon by supplied air.

Reactivating the Ni-YSZ electrode in solid oxide cells and stacks by infiltration

The solid oxide cell (SOC) could play a vital role in energy storage when the share of intermittent electricity production is high. However, large-scale commercialization of the technology is still hindered by the limited lifetime. Here, we address this issue by examining the potential for repairing various failure and degradation mechanisms occurring in the fuel electrode, thereby extending the potential lifetime of a SOC system. We successfully infiltrated the nickel and yttria-stabilized zirconia cermet electrode in commercial cells with Gd-doped ceria after operation. By this method we fully reactivated the fuel electrode after simulated reactant starvation and after carbon formation. Furthermore, by infiltrating after 900 h of operation, the degradation of the fuel electrode was reduced by a factor of two over the course of 2300 h. Lastly, the scalability of the concept is demonstrated by reactivating an 8-cell stack based on a commercial design.

Elucidating the Degradation Mechanism at the Cathode-Interlayer Interfaces of Solid Oxide Fuel Cells

Understanding degradation mechanism is essential in improving performance and long-term stability of solid oxide fuel cells. Model cells consisting of porous La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathodes were implemented on yttria-stabilized zirconia (YSZ) electrolytes with dense Gd-doped ceria (GDC) interlayers and tested in an open-circuit voltage condition at 800°C for 300 h in air to elucidate the degradation at the cathode-interlayer interfaces. The GDC films were prepared on poly-YSZ and single-crystal YSZ(100) electrolytes by pulsed laser deposition to generate dense and well-defined barrier microstructures namely granular polycrystalline (poly-GDC) and grain boundary-free single crystalline (sc-GDC) interlayers. Distinct features of the reaction phases at the cathode-interlayer interfaces were observed depending on the type of GDC interlayers. The severe SrZrO3 accumulation at the LSCF/poly-GDC interface caused the rapid cell performance degradation with the poly-GDC interlayers. Whereas, the SrZrO3 formation was suppressed successfully with the sc-GDC interlayers resulting in improved cell performance. However, the active reaction between cathode and interlayer results in the possible formation of GdFeO3 at the LSCF/sc-GDC interface and the CoO dissolution in sc-GDC interlayer appear to affect cell stability. Based on these results, plausible thermodynamic and kinetic considerations on interface chemistry and associated electrochemical behaviors were discussed.

Assessment of the Effect of Transition Metal Oxide Addition on the Conductivity of Commercial Gd-Doped Ceria

The effect of addition of transition metal oxides on the charge transport of commercially available Gd-doped ceria (Ce0.9Gd0.1O2-δ) was assessed with special emphasis on the electronic partial conductivity. The samples were doped by adding 2, 4 or 6 cat% of CoO3/4 or FeO2/3, or 2 mol% of the transition metal oxides V2O5, MnO2, and CuO, respectively. It was found that even small amounts of transition metal oxides severely change the partial electronic conductivity of ceria while the majority oxygen ion conductivity was only mildly affected: for high oxygen ion conductivity, Fe or Mn oxide addition as well as small amounts of Co oxide are beneficial, as especially the grain boundary conductivity is slightly increased. Addition of V or Cu oxide in contrast increases the minority charge carrier conductivity of electrons and thus enhances the mixed ionic-electronic conductivity. For Co oxide addition, an increasing electronic conductivity with decreasing oxygen partial pressure from 10−8 to 10−4 bar at temperatures below 600°C indicates the changing redox state of Co from divalent at low oxygen partial pressures to trivalent under ambient oxygen partial pressure.

Room Temperature Polarization Phenomena in Nanocrystalline and Epitaxial Thin Films of Gd-Doped Ceria Studied by Kelvin Probe Force Microscopy

Thin films of the composition Ce0.9Gd0.1O2-δ and with a thickness of 200 nm were prepared on an Al2O3 (0001) substrate at 720°C or room temperature, to yield epitaxial or nanocrystalline materials. The effect of the microstructure on room temperature polarization were assessed by a combination of polarization with up to ±5 V using an AFM tip and a large silver back contact followed by surface potential mapping with Kelvin probe force microscopy. The nanocrystalline sample showed a low degree of polarization, which was reversible, and a fast relaxation process. The epitaxial thin film, in contrast, was already polarized at smaller biases and showed irreversible changes of the surface potential after polarization with +5 V. For lower biases, two distinct relaxation reactions were identified: a fast redistribution of charge over a large area in the first seconds after end of polarization and a slower process in the vicinity of the polarization contact, which took several minutes to relax. The slower polarization behavior is due to a bulk chemical diffusion process with a coefficient Dδ on the order of 10−17 m2·s−1, whereas the faster polarization can be assigned to a charge carrier redistribution within a space charge layer.

Structural properties of Sm-doped ceria electrolytes at the fuel cell operating temperatures

A high temperature structural study (673–1073K) was performed by means of synchrotron x-ray diffraction and μ-Raman spectroscopy on several compositions belonging to the Ce1−xSmxO2−x/2 system with the aim to investigate the crystallographic features of Sm-doped ceria electrolytes at the fuel cell operating temperatures; ionic conductivity of samples with x ranging between 0.1 and 0.4 was measured too in order to correlate the main structural features with transport properties. A slight shift toward lower x values of the fluorite-based/hybrid region boundary is observed with increasing temperature; moreover, the coefficient of thermal expansion reveals a strong slope change close to x=0.3, which represents the crossover composition between the two atomic arrangements. The presence of C-structured RE2O3 nanodomains within the fluorite structure starting from x~0.2 is revealed by μ-Raman spectroscopy and confirmed by the behaviour of total conductivity. The ordering effect exerted at each temperature by the Sm-vacancies aggregates on the fluorite structure within the hybrid region influences the behaviour of both the intensity and the full width at half maximum of the Raman signal typical of the CeO2 structure. The obtained results are discussed in comparison to the ones deriving from the Gd-doped ceria system.

Effect of oxygen partial pressure on the microstructural, optical and gas sensing characterization of nanostructured Gd doped ceria thin films deposited by pulsed laser deposition

Microstructural properties of 10 mol% gadolinium doped ceria (CeO2) thin films that were deposited on quartz substrate at substrate temperature of 1023 K by using pulsed laser deposition with different oxygen partial pressures in the range of 50–200 mTorr. The influence of oxygen partial pressure on microstructural, morphological, optical and gas sensing characterization of the thin films was systematically studied. The microstructure of the thin films was investigated using X-ray diffraction, atomic force microscopy and Raman spectroscopy. Morphological studies have been carried out using scanning electron microscope. The experimental results confirmed that the films were polycrystalline in nature with cubic fluorite structure. Optical properties of the thin films were examined using UV–vis spectrophotometer. The optical band gap calculated from Tauc’s relation. Gas sensing characterization has been carried at different operating temperatures (room temperature to 523 K) for acetone gas. Response and recovery times of the sensor were calculated using transient response plot.

Effects of rare-earth doping on the ionic conduction of CeO2 in solid oxide fuel cells

Rare-earth-doped CeO2 have been found to enhance the ionic conductivity of ceria-based electrolytes in solid oxide fuel cells (SOFCs) because trivalent rare-earth cations can spontaneously induce oxygen vacancies. Experimentally, it has been shown that the rare-earth elements La, Nd, Sm, Gd, Tb, Dy, and Er are likely candidates for electrolyte doping. However, the performances differ for the trivalent cations, suggesting that rare-earth doping plays multiple roles instead of only increasing the oxygen vacancies. First-principles calculations are performed on a series of rare-earth-doped CeO2 systems to study the doping effects on the ionic conductivity. It is found that the migration barriers of the oxygen ions are significantly different for the different dopants and depend on the dopant's radius. Gd-, Dy-, Er-, and Tb-doping results in small migration barriers and enhances the ionic conductivity. We also calculate the formation energies (Evac) of the intrinsic oxygen vacancies due to thermal excitation. It is found that the Sm- and Gd-doped ceria systems have the smallest Evac values. The electronic structures indicate that the band gaps are not sensitive to the dopant elements but are very sensitive to the fluctuations in the oxygen content.

Sr and Zr transport in PLD-grown Gd-doped ceria interlayers

Understanding the nature of cation diffusion through the reaction barrier layer provides important information on the long-term stability of solid oxide fuel cells. In this work, model LSCF/GDC/YSZ diffusion triplets were fabricated by pulsed laser deposition. To understand the role of the barrier microstructure on cation transport, epitaxial GDC barrier layers were prepared on (100) and (111) single crystal YSZ substrates. The GDC films successfully prevented severe Sr diffusion into YSZ electrolyte. However, an active Zr transport was observed especially on the (100)-oriented GDC interlayer which is accompanied with severe pore formation. Long-term annealing at high temperature revealed nanosized SrZrO3 grains at the LSCF/GDC(100) interface. SIMS and TEM analyses indicate that Zr is primarily transported through the dislocations. By varying the GDC film thickness systematically between 10nm and 1.0μm, we demonstrate by high-resolution reciprocal space mapping that the strain thickness levels in GDC films are different. The (111)-oriented GDC film is strained to the YSZ for thicknesses up to 200nm, which is several times greater than the (100)-oriented GDC films indicating that strained layers inhibit the Zr transport. The presence of a network of dislocations in GDC provides the fast diffusion pathway for Zr.