Thin CeO2 layers were prepared by on-axis radio frequency sputtering on R-plane sapphire substrates that came from two different sources, A (A substrates) and B (B substrates). We have observed reproducible XRD rocking curves (Deltaomega, shape) depending on the source of substrates and their pre-annealing. AFM measurements reveal a clear difference between the surface topography of A and B, pre-annealed or non-pre-annealed substrate. CeO2 layers deposited on preannealed A substrate show reproducibly two-component rocking curves, a higher concentration of holes, and increased roughness. On the other hand, CeO2 layers grown on pre-annealed B substrate give singular rocking curves, and almost no holes in the layers were observed. YBa2Cu3O7 thin films, deposited on the examined CeO2 by two different methods-high pressure dc sputtering, pulsed laser deposition, show different zero magnetic field microwave absorption on temperature, depending on the shape of rocking curve. The results obtained clearly show that the substrate itself can generate CeO2 layers with two-component (supercrystallinity) rocking curves. (C) 2001 Elsevier Science B.V. All rights reserved.