Ferroelectricity of flexible Pb(Zr<sub>0.53</sub>Ti<sub>0.47</sub>)O<sub>3</sub> thin film at high temperature
Authors: Li Min , Shi Xin-Na , Zhang Ze-Lin , Ji Yan-Da , Fan Ji-Yu , Yang Hao ,   College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

Recently, flexible electronic devices have attracted extensive attention due to their characteristics of flexibility, miniaturization and portability. Flexible functional oxide thin films with high performance and stability are the basis for high-performance flexible electronic devices. Perovskite lead zirconate titanate Pb(Zr<sub>0.53</sub>Ti<sub>0.47</sub>)O<sub>3</sub> (PZT) at "morphotropic phase boundary" indicates excellent ferroelectricity and piezoelectricity, and has broad prospects in flexible non-volatile memories, sensors and actuators. Moreover, high-temperature stable flexible memories and sensors have received increasing attention due to the escalating complexity of the external environment. In the present work, Pb(Zr<sub>0.53</sub>Ti<sub>0.47</sub>)O<sub>3</sub>/SrRuO<sub>3</sub>/BaTiO<sub>3</sub> (PZT/SRO/BTO) heterostructures are prepared by pulsed laser deposition on high temperature resistant two-dimensional layered fluorphlogopite mica substrates. Afterward, flexible epitaxial PZT thin films are obtained by mechanical stripping. The ferroelectricity, piezoelectricity and high temperature characteristics of PZT thin films are investigated. The thin films show superior ferroelectricity at room and high temperatures. At room temperature, the thin films exhibit excellent ferroelectricity with a remnant polarization (<i>P</i><sub>r</sub>) of ~<inline-formula><tex-math id="M2">\begin{document}$ {\rm{65}}\;{\text{μ}} {\rm{C/c}}{{\rm{m}}^{\rm{2}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M2.png"/></alternatives></inline-formula>. A saturation polarization (<i>P</i><sub>s</sub>) of ~<inline-formula><tex-math id="M3">\begin{document}$ {\rm{80}}\;{\text{μ}} {\rm{C/c}}{{\rm{m}}^{\rm{2}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M3.png"/></alternatives></inline-formula> and a coercive field (<i>E</i><sub>c</sub>) of ~100 kV/cm are also observed. In addition, after bending the thin films to a 1.5 cm radius 10<sup>4</sup> times, their ferroelectricity does not show deterioration at room temperature. In order to study the ferroelectricity of PZT thin films at high temperature, <i>P-E</i> loops from 27 ℃ to 275 ℃ are tested. The results show that the films still show excellent ferroelectricity with a <i>P</i><sub>r</sub> of ~<inline-formula><tex-math id="M4">\begin{document}$ {\rm{50}}\;{\text{μ}} {\rm{C/c}}{{\rm{m}}^{\rm{2}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M4.png"/></alternatives></inline-formula> and a <i>P</i><sub>s</sub> of ~<inline-formula><tex-math id="M5">\begin{document}$ {\rm{70}}\;{\text{μ}} {\rm{C/c}}{{\rm{m}}^{\rm{2}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M5.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20181967_M5.png"/></alternatives></inline-formula> at 275 ℃. The present work provides a basis for the application of flexible epitaxial PZT thin film. Especially, the ferroelectricity of flexible PZT thin films at high temperature provides a possibility of obtaining high-temperature flexible electronic devices.