Pulsed laser deposition of yttria stabilized zirconia for solid oxide fuel cell applications

Yttria stabilized zirconia (YSZ) films were grown by pulsed laser deposition (PLD) from a 8YSZ target using a KrF excimer laser source (248 nm). The films have been deposited under oxygen atmospheres on porous NiO/YSZ substrates heated from room temperature to 600 degreesC. YSZ films were obtained in the range of 1-2 mum thickness. The films have been investigated with respect to surface morphology, microstructure and film-substrate interface interaction. The film morphology varied from columnar to an irregular crystalline structure depending on the oxygen pressure and the substrate temperature, In all cases the films consisted of YSZ with the cubic fluorite structure. The formation of oxide layers under low oxygen pressures on the NiO/YSZ substrates is due to a film-substrate redox interaction. The NiO grains close to the coating interface are partially reduced and serve as an oxygen source for the oxidation of the film. The measured He leakaae rates to analyze the gas tightness of the YSZ films have so far shown no improvements as compared with uncoated substrates. (C) 2002 Elsevier Science B.V. All rights reserved.