Structure and electrical properties of Bi _0.5Na _0.5TiO₃ 0-3 composite lead-free thick films

The use of piezoelectric films in high-frequency ultrasonic transducers requires thick, dense, and crack-free films with excellent piezoelectric properties. In this work, Bi_0.5Na_0.5TiO₃ (abbreviated to BNT) 0-3 composite lead-free ferroelectric thick films have been successfully prepared by a modified 0-3 composite technique. The BNT fine ceramic powders were dispersed in a sol-gel solution of the same composition to form a uniform slurry, which was deposited on (111) Pt/TiO₂/SiO ₂/Si substrates using spin-coating and then annealed at 700?C. The morphology, microstructure, dielectric properties, ferroelectric properties and leakage current densities of BNT composite thick films have been investigated. BNT ceramic powders sintered at a series of temperatures were used to prepare the thick films. X-ray diffraction analysis indicates that the BNT 0-3 composite thick films exhibit a pure perovskite structure. The electrical properties of the composite films depend strongly on the sintering temperature of BNT ceramic powders.. © 2014