Epitaxial Ba(Zr0.3Ti0.7)O-3 thin films were grown on (LaAlO3)(0.3)(Sr2AlTaO6)(0.35) (001) single-crystal substrates by Pulsed laser deposition at 700 degrees C in different oxygen partial pressures ranging from 6.7 Pa to 40.0 Pa. A strong correlation is observed between the structure and dielectric properties for the Ba(Zr0.3Ti0.7)O-3 thin films. The tetragonal distortion (ratio of in-plane and out-of-plane lattice parameter, a/c) of the films depends on the oxygen partial pressures. a/c varies from 0.989 at 6.7 Pa to 1.010 at 40.0 Pa, indicating the in-plain strain changes from compressive to tensile. The in-plain strain (either compressive or tensile) shifts the Curie temperature of the Ba(Zr0.3Ti0.7)O-3 thin films dramatically. Surface morphology and dielectric properties of Ba(Zr0.3Ti0.7)O-3 thin films have a strong dependence of the oxygen partial pressure. The film grown 26.7 Pa, which corresponds to a moderate in-plain tensile strain and a Curie temperature of similar to 30 degrees C, shows the largest relative permittivity, tunability and the best figure of merit in a broad frequency range (1 kHz-500 MHz), which may be a promising candidate for room-temperature microwave device applications. (C) 2008 Elsevier B.V. All rights reserved.