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Keywords:

  • pulsed laser deposition;
  • LSCF;
  • thin films;
  • solid oxide fuel cells;
  • nanostructure

Abstract

Pulsed Laser Deposition (PLD) was used to prepare thin films with the nominal composition La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF). The thin film microstructure was investigated as a function of PLD deposition parameters such as: substrate temperature, ambient gas pressure, target-to-substrate distance, laser fluence and frequency. It was found that the ambient gas pressure and the substrate temperature are the key PLD process parameters determining the thin film micro- and nanostructure. A map of the LSCF film nanostructures is presented as a function of substrate temperature (25–700 °C) and oxygen background pressure (0.013–0.4 mbar), with film structures ranging from fully dense to highly porous. Fully crystalline, dense, and crack-free LSCF films with a thickness of 300 nm were obtained at an oxygen pressure lower than 0.13 mbar at a temperature of 600 °C. The obtained knowledge on the structure allows for tailoring of perovskite thin film nanostructure, e.g., for solid oxide fuel cell cathodes. A simple geometrical model is proposed, allowing estimation of the catalytic active surface area of the prepared thin films. It is shown that voids at columnar grain boundaries can result in an increase of the surface area by approximately 25 times, when compared to dense flat films.