Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Abstract

is prepared to simulate a solid oxide fuel cell. This setup allows observation of Sr diffusion by observing SrZrO 3 formation using X-ray diffraction while annealing. Subsequent electron microscopy confirms the results. This approach presents a simple method for assessing the quality of CGO barriers without the need for a complete fuel cell test setup. CGO films with thicknesses ranging from 250 nm to 1.2 µm are tested at temperatures from 850 °C to 950 °C which yields an in-depth understanding of Sr diffusion through CGO thin films that may be of high scientific and technical interest for implementation of novel fuel cell materials. Sr is found to diffuse along column/grain boundaries in the CGO films but by modifying the film thickness and microstructure the breaking temperature of the barrier can be increased.2 2

Magnetron sputtered gadolinia-doped ceria diffusion barriers for metal-supported solid oxide fuel cells

“…First, we demonstrate how deposition of GDC can be tuned to form effective diffusion barriers to metal-supported cells. Furthermore, we prove the Sr diffusion mechanism to be as previously demonstrated in a model system [18].…”

“…When synthesizing GDC coatings for ceramic SOFCs high deposition temperatures are often used to grow coatings sufficiently dense to prevent Sr diffusion [11,17]. In a recent study, we showed using a model system that the main route for Sr diffusion in sputtered GDC films are along underdense column boundaries which can be densified and/or limited by increasing the adatom mobility [18]. Besides the deposition temperature, other ways to increase adatom mobility includes increasing the ionization degree of the plasma and applying a substrate bias.…”

Aluminum‐enhanced alkali diffusion from float glass to PVD‐sputtered silica thin films

“…In order to limit the diffusion of alkali from the glass substrate to the active layers, barrier layers are deposited on the glass surface . Alkali diffusion through a barrier layer has been studied for a variety of compositions, such as silicon nitride, silica, alumina or ceria, and for different deposition processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or sol‐gel coating . One of the most common compositions of barrier layers is silica, which is usually doped with aluminum in PVD coaters in order to increase the deposition rate .…”

Nature and Functionality of La0.58Sr0.4Co0.2Fe0.8O3-δ/ Gd0.2Ce0.8O2-δ/ Y0.16Zr0.84O2-δInterfaces in SOFCs

“…One drawback of these thin layers (usually only a few 100 nm) are the short diffusion paths for Sr and Zr species, via defects or grain boundaries, which can still lead to the formation of SrZrO 3 at the LSCF/GDC interface. 17,26,28 A much larger interlayer thickness is achieved using a screen-printed ASC (cf. Fig.…”