Piezoelectric properties of polymer/lead-free ceramic composites

Thermoplastic/lead-free piezoelectric ceramic composite have been prepared. Sodium niobate (NaNbO3) has been chosen for its high Curie temperature. Moreover, it could be synthesized with two different morphologies: NaNbO3 nanowires (NN NW's) and NaNbO3 particles (NN P's). The filler has been dispersed in thermoplastic matrices with different dielectric permittivities ϵM: PA11 ( ϵM= 2) and polyvinylidene fluoride (PVDF) (ϵM= 10). Due to polarization conditions, only ceramic particles are poled. The piezoelectric coefficient (d33) has been measured in composites. The higher d33 is recorded in composites based on PA11 (d33 = 6.5 pC.N−1 for 30 vol. % NN NW's). The influence of the NN aspect ratio on PVDF/NN composites has been analysed: the higher d33 (d33 = 2.6 pC.N−1 for 25 vol. %) is recorded in PVDF/NN P's. The major interest of these hybrid lead-free piezoelectric composites is mild poling conditions, ductility and thermal stability of piezoelectric performances.