Investigation on Large-area and Flexible PZT/PVB/additives Composite Films for New Piezoelectric Sensor Application

In order to satisfy the requirement of the structural health monitoring (SHM) for the light sensor with high sensitivity, a novel large-area and flexible lead zirconate tiatnate (PZT)/polyvinyl-butyral (PVB)/additives composite film was fabricated by tape casting method. The microstructure, piezoelectric and diezoelectric properties of the PZT/PVB/additives composite films were investigated systematically. Thanks to the additives (dibutyl phthalate + castor oil), the flexibility and uniformity of PZT/PVB composite films are improved significantly compared with conventional PZT/PVB composite films. The surfaces of the PZT/PVB/additives film are smooth and more resistant to surface cracking. From the SEM micrographs, it can be observed that micro holes exist in the PZT/PVB composite films and agglomeration phenomenon is noticeable. On the contrary, PZT particles are well dispersed in PVB matrix and there is few obvious micro hole in the PZT/PVB/additives composite films. Furthermore, from the EDS results, it can be seen that PZT particles deposit in the bottom surface of the PZT/PVB film, however uniform deposition of PZT particles is achieved in the PZT/PVB/additives. In addition, due to the additives, the improvement of the piezoelectric and dielectric properties of PZT/PVB composite films is observed at a high volume fraction of PZT (phi (PZT) >60%). At phi (PZT) = 85% the largest piezoelectric constant (d(33)) reaches 44pC/N, which is much high than that of the reported PZT/PVDF films. Moreover, the dielectric constant (epsilon) of the PZT/PVB/additives film (at room temperature and a frequency of 1 kHz) is higher that of the PZT/PVB film with the same phi (PZT), and the dielectric losses (tan delta) is lower. Both the improved piezoelectric and diezoelectric properties are desirable for the new piezoelectric sensor application.