Physical and Electrochemical Characteristics of Pulsed Laser Deposited La_0.6Sr_0.4CoO_3−δ-Ce_0.9Gd_0.1O_2−δNanocomposites as a Function of the Mixing Ratio

Binary nanocomposite thin films of lanthanum strontium cobaltite and gadolinia-doped ceria (La 0.6 Sr 0.4 CoO 3−δ -Ce 0.9 Gd 0.1 O 2−δ , LSC-GDC) were prepared using pulsed laser deposition (PLD) for application as cathodes of low-temperature operating solid oxide fuel cell (LT-SOFC). The thin films were fabricated under identical deposition conditions, but the LSC:GDC mixing ratio was varied. The PLD-processed LSC-GDC nanocomposites exhibit different physical and electrochemical properties than do conventional powder-processed composite SOFC cathodes. The LSC:GDC mixing ratio not only alters the composition of the LSC-GDC nanocomposite thin films but also affects their crystallographic orientation and microstructure. The major component of the composite appears to govern the physical properties of the LSC-GDC nanocomposite thin films. The electrochemical properties measured with AC impedance spectroscopy during the half-cell tests reveal that the electrochemical performance of the LSC-GDC nanocomposite cathode is enhanced as the LSC content in the composite increases, which is in contrast to the behavior of powder-processed composite cathodes. The present study provides important insight into the design and application of thin-film-processed nanocomposite electrodes.