Effect of Nb doping on the microstructure and electrical properties of 0.5BZT-0.5BCT thin films prepared by the sol-gel method

In this study, Nb-doped (0.00 & LE; x & LE; 0.025) lead-free 0.5BZT-0.5BCT films were prepared on Pt/Ti/SiO2/(100)Si substrates by the sol-gel method. The effects of Nb content on the structure, diffusion phase transformation, dielectric and ferroelectric properties of the films were investigated. XRD and Raman spectra indicated the coexistence of T and R phases at room temperature in all the films, and the tetragonality of the films decreased with increasing Nb content. The ferroelectric-paraelectric phase transition temperature decreased, and the diffuseness phase transition gradually increased with increasing Nb content. Low Nb doping caused significant improvement in dielectric and ferroelectric properties at room temperature. Excellent dielectric properties with a large dielectric constant (& epsilon;r = 3556) and high remanent polarization (Pr of 7.2 & mu;C/cm2) were obtained for the films with x = 0.002. A large improvement in dielectric properties indicates that these films might be a potential material for dielectric applications.