Preparation And Electrical Properties Of Flexible PbZr_0.52Ti_0.48O₃ Ferroelectric Thin Films

Pb(Zr_1-xTix)O₃,as a typical ferroelectric material,has been widely used in micro-mechanical system,ferroelectric memory,sensor and other fields.However,as for the application of flexible micro-devices,it is necessary to explore problems in the architectural design of flexible device,the quality of films and film/substrate interface and device performance under flexible bending.It is known that the properties of Pb?Zr1-xTix?O3 ferroelectric thin films are closely related to the ferroelectric polarization,therefore it is important to study the effects of external stress on the ferroelectric polarization.In this paper,the preparation of PbZr_0.52Ti_0.48O₃?PZT?thin films and properties of the prepared films in the bending state were studied.This paper mainly contains the following three aspacts:?1?The preparation and ferroelectricity of high-quality PZT ferroelectric thin films were studied.The epitaxial films by pulsed laser deposition were prepared on?001?SrTiO3 substrates through the pure-phase and high-density target which was prepared with excess lead.The suitable growth parameters of the PZT thin films,such as the substrate temperature and the laser energy,were confirmed by the characterization with the X-ray diffraction and atomic force microscopy.After annealing,the hysteresis loops of the PZT films were rectangular with the saturation polarization of 78 ?C/cm² and the residual polarization of 65?C/cm² at 1 kHz.?2?The preparation and microcosmic piezoelectric properties of flexible PZT thin films were studied.The ferroelectric thin films on 10-?m mica with SrRuO3?SRO?buffered layer were prepared with the optimal growth parameters,which had nano-level surface and preferred orientation.The piezoelectric response in Pt/SRO/PZT prepared on mica was much higher than that in the films prepared on the hard substracts,which could be explained by the amplifying d31 model.The polarization switch introduced by the tip bias remained unchanged even after the films were bent with 1.4 mm radius,bent for 50 hours or bent for 10,000 times.?3?The macroscopic electrical properties of the bending PZT thin films were studied.It was founded that the dielectric tunability of the Pt/SRO/PZT/SRO/Pt remained>90%after the films were bent.Furthermore,the saturated polarization was>60 ?C/cm² after repeatedly bending for 10,000 times at 2.2 mm radius.It was because the small internal stress in the ultra-thin flexible films,so the stress introduced by the bending was small,whose value was up to the thickness of the substrate and the bending radius.In summary,the research concerning the microcosmic piezoelectric properties and macroscopic electric properties of the flexible PZT thin films in the bending condition are significant in the application of ferroelectric materials in the wearable electronic devices,such as the flexible piezoelectric micro-sensors and ferroelectric memories.