The effect of an oxygen atmosphere on the microwave dielectric properties of Bi2Zn2/3Nb4/3O7 thin films

Monoclinic Bi2Zn2/3Nb4/3O7 (m-BZN) thin films were deposited by pulsed laser deposition on fused silica substrates at different oxygen pressures. Microwave dielectric and Raman scattering studies were systematically carried out on films that had been annealed at 600 degrees C after deposition. The dielectric constant of films changes in the range 56-71 due to varying the oxygen pressure during deposition. X-ray diffraction measurements indicate that the BZN thin films deposited at the oxygen pressure of 10 Pa have the best crystalline quality. Atomic force microscopy results show that the surface roughness of the m-BZN film increases with the increase of oxygen pressure. The anomalous change in two higher-frequency Ag modes appearing at 774 and 852 cm(-1) with varying oxygen pressure also suggests a nonequivalent change in the oxygen octahedra around the Nb and Zn and is closely related to the microwave dielectric properties of the thin films. (C) 2010 Elsevier Ltd. All rights reserved.