Study of Lead-Free Ferroelectric Composite Coatings by Impedance Spectroscopy

The aim of the study is preparation and electrical characterization of lead-free ferroelectric oxide BaSrTiO₃ in composition with piezoelectric polymer. The properties of the deposited films were compared with pure oxide. Scanning electron microscopy showed regular distribution of particles and homogeneous composition of both components. The dielectric properties (electric permittivity and dielectric loss) were investigated at different temperatures ranged from 5 ^oC to 130 ^oC. Impedance spectroscopy was applied in the frequency range 100 Hz-100 kHz. It was demonstrated that the dielectric constant increase with addition of piezoelectric polymer to the ceramic phase. Based on the equivalent electrical circuit parameters extraction (contact resistance and capacitance comparisons), it can be seen that the interface conditions at the electrodes are improved after inserting piezoelectric polymer. As well, interpretation of the plots of the complex impedance vs. frequency and real part of the impedance vs. imaginary part, gives information about the polarization process, revealing in the structures.