Preparation of doped lanthanum gallate electrolyte for SOFC by pulsed laser deposition

In this study, doped lanthanum gallate (LSGM with the composition La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-, LSGMC with the composition La_0.8Sr_0.2Ga_0.8Mg_0.15Co_0.05 O_3-) films for an electrolyte of the solid oxide fuel cell (SOFC) were prepared by pulsed laser deposition (PLD) technique. In the vacuum chamber, LSGM or LSGMC targets were set on the rotating target holder. A KrF excimer laser was introduced into the chamber at an incident angle of about 45 degree. The doped LaGaO₃ film was deposited onto NiO substrates without heating in argon ambient gas. The NiO substrate can be used directly as an electrode in the fabrication of the SOFC. The deposited LSGM films were characterized by X-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS) and scanning electron microscopy (SEM). As-deposited films were amorphous. After post annealing at 1273K for 6-10 hours, crystalline LaGaO₃ was obtained. Films with thickness greater than several 10 m showed an uniform and dense morphology. No gas leakage was found using thick films, which is an important characteristic for an electrolyte in fuel cells. The composition of the deposited films was slightly different to that of the target.