Structure and microwave dielectric properties of Bi1.5Zn1.0Nb1.5O7 thin films deposited on alumina substrates by pulsed laser deposition

Bi1.5Zn1.0Nb1.5O7 (BZN) thin films were deposited on polycrystalline alumina substrates by pulsed laser deposition at different substrate temperatures. The phase structure and surface morphology were characterized using X-ray diffractometer (XRD) and atomic force microscopy. Microwave dielectric properties were performed using split-post dielectric resonator method at spot frequencies of 10, 15 and 19GHz, respectively. The XRD results indicate that the as-deposited Bi1.5Zn1.0Nb1.5O7 thin films deposited at 650°C are amorphous in nature. The dielectric permittivity and loss tangent of the amorphous BZN thin films are 75.5 and 0.013 at 10GHz, respectively. As the measure frequency increased to 19GHz, the dielectric permittivity slightly decreases and loss tangent slightly increases. BZN thin films were crystallized after the post-annealing by a rapid thermal annealing in air for 30min. The crystallized BZN thin films exhibit the excellent dielectric properties and frequency responses. The dielectric permittivity and loss tangent of the crystallized BZN thin films are 154 and 0.038 at 10GHz, respectively. ► Bi1.5Zn1.0Nb1.5O7 BZN thin films were deposited on polycrystalline alumina substrates. ► Dielectric properties were evaluated by split-post dielectric resonator method. ► BZN films exhibit excellent dielectric properties in the microwave frequency range. ► The dielectric constant of crystallized BZN films is 154 at 10GHz