The growth mechanism in general and the biaxial alignment in detail were investigated for thin films of yttria stabilized zirconia deposited by unbalanced magnetron sputtering on non-aligned polycrystalline stainless steel and amorphous glass substrates. A strong influence of the Ar/O-2 flow ratio on the preferential out-of-plane orientation was observed. The out-of-plane orientation changed from nearly perfect [002] to a mixture of 30% [220] and 70% [111] with increasing 02 partial pressure. It was concluded that the change from a [002] to a [111] out-of-plane orientation is caused by an increased adatom mobility during the growth. The change from a [002] to a [220] out-of-plane orientation is believed to be a consequence of a change in the plasma composition due to an increased oxygen partial pressure. By tilting the substrate with respect to the sputter source, an in-plane aligned YSZ layer was obtained. (c) 2005 Elsevier B.V. All rights reserved.