Effect of the fabrication method on the functional properties of BaTiO3: PVDF nanocomposites

This paper deals with the preparation and characterization of nanocomposite (NC) materials, comparing different technologies for sample fabrication, in view of their possible application as piezoelectric sensors. Those NCs consist on BaTiO3 nanoparticles embedded into a polyvinylidene fluoride matrix, where both the ceramic and the polymeric phases could exhibit ferroelectricity. In particular, we compare the properties of samples prepared through three different methods, i.e., solvent casting, enabling a fast realization, spin-coating, which allows to realize thin flexible films particularly interesting for large area sensors, and hot embossing, which is exploited to modify the residual porosity in the thick films. The influence of the fabrication techniques on the physical and chemical properties is investigated. Different electrode materials have been tested and compared, ranging from sputtered Pt to an engineered thermally evaporated Ti/Au bilayer. Leakage current, polarization, displacement curves, and piezoelectric coefficient d (33) are evaluated by small signal indirect measurements, comparing the properties of different materials and understanding how processing technologies influence the sensor performances by acting on the functional materials.