Piezoelectric Properties And Applications Of Flexible Pb(Zr_0.53Ti_0.47)O₃ Thin Films

The explosion of mobile Internet technology has promoted the vigorous development of portable personal electronic products.In the future,electronic products will develop towards the direction of flexible and flexible,small and easily integrated,and high-performance and multi-functional.Compared with the traditional electronic devices,flexible electronic devices have better flexibility.So they can meet the requirement of various devices to a certain extent and adapt to different working environments.Piezoelectric sensors are also developing towards flexibility in recent years.This paper focuses on the preparation of flexible lead zirconate titanate(Pb(Zr_0.53Ti_0.47)O₃,PZT)epitaxial thin films.Microstructure characterization,piezoelectric properties,and their applications in aircraft structure health monitoring have also been included in the present work.The specific works are as follows:1.Preparation and microstructure characterization of flexible PZT epitaxial thin films:Lead zirconate titanate(Pb(Zr_0.53Ti_0.47)O₃,PZT)epitaxial thin film was successfully prepared by pulsed laser deposition technology.The substrate material was selected as mica.X-ray diffraction technique was used to characterize the growth direction of epitaxial thin films,analyze the crystal structure and calculate the specific lattice parameters.The surface flatness and particle size of the thin film were observed by atomic force microscopy,and the internal structure of PZT epitaxial thin film was characterized by transmission electron microscopy.The above experimental results show that epitaxial PZT films grown along a single orientation(111)have been successfully prepared on the mica substrate and show good microstructure.2.Piezoelectric property of flexible PZT epitaxial film:Piezoelectric response signals of PZT epitaxial thin film samples were measured with a pressure-electric microscope,and the piezoelectric coefficient d₃₃(24pm/V)was quantitatively characterized,and compared with that of the thin film after mechanical stripping of the rigid mica substrate(110pm/V),it was found that the piezoelectric coefficient of the flexible PZT thin film was greater than that of the rigid PZT thin film.As is known to all,d₃₃ value of PZT thin film on rigid substrate is weaker than that of PZT piezoelectric ceramics.Compared with PZT thin film on rigid substrate,flexible PZT thin film after stripping has similar piezoelectric properties with PZT ceramics.We analysis the reasons of the phenomenon of the experiment is due to the effect of strain clamping of the rigid substrate,and the characteristics of mica substrate determines its piezoelectric properties significantly,due to the interaction between the mica substrate layer is the weak van der Waals interactions,will be after the mechanical stripping mica substrate,reduce the clamping function of substrate to form a huge d₃₃.3.Electrical properties of the film after mechanical fatigue:In order to prove the stability and reliability of piezoelectric properties of PZT/SRO/STO/mica flexible film,the fatigue resistance of flexible film samples can be tested by mechanical bending.The experimental results showed that the ferroelectric and piezoelectric properties of the thin film were not significantly affected after5000?10000 mechanical bending,and the piezoelectric coefficient d₃₃ remained around 110pm/V4.Application of structural health monitoring:Lamb wave is an ultrasonic wave first proposed by Horace Lamb in 1917.It is a stress wave formed by the coupling of longitudinal wave and shear wave when the thickness of solid plate is in the same order of magnitude as the wavelength of sound wave.In general,Lamb wave excited by excitation signal is very sensitive to damage structure,and it is easy to identify the difference of Lamb wave caused by damage,so we can use Lamb wave to characterize defects.In Lamb wave nondestructive testing system,the previous experiments using Pb(Zr,Ti)O₃piezoelectric ceramics as incentives and to motivate and receiving of Lamb wave sensing element,however,because of the hardness and thickness of the ceramic and brittle in the surface structure of the inherent characteristics of the application of severely limits,such as difficult to achieve surface structure and the overall combination of pottery and porcelain,and affect the mechanical movement of the measured structure can increase the weight.The PZT/SRO/BTO/Mica flexible thin film prepared in this experiment not only has good stability and high piezoelectric coefficient d₃₃(110pm/V),which is conducive to receiving Lamb wave as a sensor in the Lamb wave response system,but also can be attached to the curved aero-aluminum plate to realize defect detection.Lamb wave with frequency of400 k Hz was selected for the damage monitoring experiment of aluminum plate structure.At the same time,it is proved that mechanical fatigue has little influence on the piezoelectric state of flexible PZT thin film,which ensures the stability and reliability of the flexible PZT thin film in practical application in the future.