a b s t r a c tThe growth and electrochemical properties of gadolinia-doped ceria (GDC) interlayers deposited by biasassisted magnetron sputtering in solid oxide fuel cells have been investigated. Such interlayers act as diffusion barriers to protect the yttria-stabilized zirconia electrolyte, preventing possible degradation when mixed ionic-electronic conductor (La,Sr)(Co,Fe)O 3−ı is used as the cathode. The dependence of the applied bias during the sputtering deposition on both the interlayer microstructure and fuel cell performance has been studied in anode-supported single cells. The main experimental results showed that bias-assisted sputtering of GDC interlayers produced microstructures denser than those of unbiased depositions, which resulted in increased electrochemical properties of fuel cells.
The effects of both temperature and applied bias power during the sputtering of gadolinia-doped ceria (GDC) interlayers used as diffusion barriers in anode-supported solid oxide fuel cells (SOFCs) were studied. Scanning electron microscopy analysis revealed that increasing the applied bias power, in the 0–300 W range, increasingly promotes the deposition of continuous and dense interlayers. Such feature was mirrored in the electrochemical performance of single cells that exhibited
∼15%
enhancement of the power density of an SOFC with bias-assisted sputtered interlayers. In addition, fuel cells having interlayers deposited in the
400–800°C
temperature range exhibited similar microstructure and electrochemical performances, indicating that the applied bias allows for the sputtering of GDC protective interlayers at relatively lower temperatures than unbiased depositions. The presented results evidenced that bias-assisted sputtering is an effective technique for the fabrication of high performance anode-supported SOFCs.
GaN films were implanted with Er and Eu ions and rapid thermal annealing was performed at 1000, 1100 and 1200 ºC in vacuum, in flowing nitrogen gas or a mixture of NH 3 and N 2 . Rutherford backscattering spectrometry in the channeling mode was used to study the evolution of damage introduction and recovery in the Ga sublattice and to monitor the rare earth profiles after annealing. The surface morphology of the samples was analyzed by scanning electron microscopy and the optical properties by room temperature cathodoluminescence (CL). Samples annealed in vacuum and N 2 already show the first signs of surface dissociation at 1000 ºC. At higher temperature, Ga droplets form at the surface. However, samples annealed in NH 3 +N 2 exhibit a very good recovery of the lattice along with a smooth surface. These samples also show the strongest CL intensity for the rare earth related emissions in the green (for Er) and red (for Eu). After annealing at 1200 ºC in NH 3 +N 2 the Eu implanted sample reveals the channeling qualities of an unimplanted sample and a strong increase of CL intensity is observed.
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