Enhanced tunable dielectric properties of Ba 0.5Sr 0.5TiO 3/Bi 1.5Zn 1.0Nb 1.5O 7 multilayer thin films by a sol-gel process

Ba0.5Sr0.5TiO3(BST)/Bi1.5Zn1.0Nb1.5O7(BZN) multilayer thin films were prepared on Pt/Ti/SiO2/Si substrates by a sol–gel method. The structures and morphologies of BST/BZN multilayer thin films were analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscope. The XRD results showed that the perovskite BST and the cubic pyrochlore BZN phases can be observed in the multilayer thin films annealed at 700°C and 750°C. The surface of the multilayer thin films annealed at 750°C was smooth and crack-free. The BST/BZN multilayer thin films annealed at 750°C exhibited a medium dielectric constant of around 147, a low loss tangent of 0.0034, and a relative tunability of 12% measured with dc bias field of 580kV/cm at 10kHz.