Ba0.5Sr0.5TiO3/Bi1.5Zn1.0Nb1.5TiO7 multilayer thin films prepared by sol–gel method

Ba0.5Sr0.5TiO3/Bi1.5Zn1.0Nb1.5O7 (BST/BZN) multilayer thin films were prepared on Pt/Al2O3 substrates by sol–gel method. The structure, morphology, and tunable dielectric properties of BST/BZN thin films were investigated. X-ray diffraction results showed that the structure of BST/BZN multilayer thin films was composed of a cubic BZN pyrochlore phase and a cubic BST perovskite phase. The diffraction pattern confirmed that there was no measurable reaction occurred between the BST and BZN layers. The field-emission scanning electron microscope (FESEM) showed that the surface of BST/BZN multilayer thin films was crack-free and compact. The dielectric constant and loss tangent of the BST/BZN multilayer thin films were 106 and 0.011 at 10 kHz, respectively. The dielectric tunability was 10% under dc bias field of 355 kV/cm at 10 kHz. The medium dielectric constant, low loss tangent and tunability of the dielectric constant suggest that BST/BZN multilayer thin films have potential application for tunable microwave device applications.