Enhanced multifunctionality through the combined effect of lead-free piezoelectric and magnetostrictive phases in the polymer matrix composite

In this work, the production of polymer composites by hot pressing, incorporating barium calcium zirconium titanate (BCZT) and cobalt ferrite (CF) particles into a polyvinylidene difluoride (PVDF) matrix, was explored for the first time. The effect of CF content on the material's functional properties and the influence of the active phase quantity on the final flexible films were evaluated. Results showed that neither the CF content nor the active phase amount affected the formation of the electro-active PVDF β-phase. Dielectric permittivity was slightly influenced by CF content, but mainly increased due to the BCZT filler. Ferroelectric properties were primarily controlled by the filler phase amount. Piezoelectric charge coefficients (d33) increased with higher BCZT filler fraction. However, piezoelectric voltage coefficients (g33) slightly decreased (or remained almost similar) due to higher dielectric permittivity of composite samples with higher BCZT content. The magnetic properties revealed that CF content significantly impacted magnetization but not coercivity. Energy harvesting tests using impulse hammer loading indicated that composites with lower CF content generated up to 20 V of output voltage and approximately 400 μW of power. These findings demonstrate the potential of these composites for next-generation devices and applications.