Piezoferroic: Multi-stacked hard/soft Pb(Ti,Zr)O3 films deposited through wet chemical method

Abstract

Improving the piezoelectric performance of thin film piezoelectric devices is vital for their future application. In this research, the multi-stacked hard/soft piezoelectric lead zirconate titanate (PZT) films with improved ferroelectric properties are introduced. The films are achieved by sol-gel dip coating deposition of the layers of PZT doped with niobium (PNZT) and iron (PFZT) as soft and hard ferroelectrics, respectively. Different sequences of the layer deposition are applied to form various multi-stacked hard/soft composites. The films demonstrate near stoichiometry composition and high quality crack-free surfaces. The polarization-electric field loops illustrate that the composite can not only enhance the polarization significantly compared to the soft PNZT, but also maintain high coercive field and provide square shaped polarization-electric field loops. The results show that the remanent polarization of 94.1 μC cm−2 along with the coercive field of 5.9 kV/cm are achieved in the 10-layer double PFZT/double PNZT multi-stacked film, which are much improved compared to PZT, PFZT, and PNZT films. Moreover, dielectric constant of 2535 at 1 kHz is obtained in this sample. These intriguing properties of hard/soft composite can arise from polarization interaction of composite layers and diffusion ions through the layers.