Characteristics of BNT Films Synthesized by a Hydrothermal Method

Thin films of lead-free piezoelectric ceramics (Bi1/2Na1/2)TiO3 (abbreviated as BNT) were prepared on pure titanium substrates by a hydrothermal method. Several properties of BNT films synthesized in various Bi3+ and Ti4+ concentrations of starting materials were investigated using SEM, EDX, XRD and other instruments. Moreover, the effects of ion concentrations of starting materials on permittivity and piezoelectric effect of BNT films were discussed. The Bi2O3 crystals were more deposited on the surface of films with the increase of the concentration of Bi3+. The relationship between the deflection and applied electric field was measured on unimorph cantilever type actuators made from three samples which had different XRD patterns. The results showed that the piezoelectric effect of BNT films was dependent on the crystallization level of BNT.