DC sputtering of yttria-stabilised zirconia films for solid oxide fuel cell applications

Yttria-stabilised zirconia (YSZ) thin films were dc-sputtered and investiga ted with respect to surface morphology, microstructure and film-substrate i nterface interaction. The films were deposited under argon/oxygen atmospher es on NiO/YSZ substrates heated to between 500 and 700 degreesC. Dense and crack-free coatings were obtained in the thickness range of 1 to 10 mum. Th e film morphology varied from columnar to crystalline structure depending o n the oxygen pressure and the substrate temperature. Whereas the coated fil ms consisted of YSZ with cubic and tetragonal crystal structure under low o xygen atmospheres, the same deposition experiments on Al2O3 substrates reve aled highly disordered layers of cubic YSZ. The formation of oxide layers o n the NiO/YSZ substrates is due to a film-substrate redox interaction. The NO grains close to the coating interface are partially reduced and serve as an oxygen source for the oxidation of the film. An exponential decay of th e gas leakage vs. coating thickness was found. (C) 2001 Elsevier Science Lt d. All rights reserved.