Crystalline alumina-zirconia nanocomposites have been synthesized at 450 degrees C and 750 degrees C with reactive magnetron sputtering using radio-frequency power supplies. The composition of the films ranged from pure alumina to pure zirconia as measured by ion beam techniques. Microstructural characterization showed the presence of monoclinic zirconia in the pure zirconia films and gamma-alumina in the pure alumina films while the nanocomposites contained either an amorphous compound, gamma-alumina, cubic zirconia or a mixture of these. The grain size was similar to 5 nm for the nanocomposite compared to larger grains in the pure oxide films. Electron energy loss spectroscopy showed a clear progression from the pure alumina to the pure zirconia. (C) 2007 Elsevier B.V. All rights reserved.