Mechanism of grain growth and excellent polarization, dielectric relaxtion of La3+, Nd3+ modified PZT nano-films prepared by sol–gel technique

Abstract

Ferroelectric PbZr0.52Ti0.48O3 film and its partial substitutions by rare earth ions La3+ and Nd3+ Pb0.9(La/Nd)0.1Zr0.52Ti0.48O3, grown on Pt(111)/Ti/SiO2/Si(100) substrates, were prepared via sol–gel and rapid thermal processes. Structural characterization by X-ray diffraction and scanning electron microscopy showed that Pb(Zr0.52Ti0.48)O3 and Pb0.9La0.1(Zr0.52Ti0.48)O3 films are of (111) preferred orientation but Pb0.9Nd0.1(Zr0.52Ti0.48)O3 is more inclined to (100) reflection though both are of tetragonal perovskite structure. The results indicate that the piezoelectric properties of PZT thin films can be improved by doping La3+ and Nd3+ substituted A-site. The d33 can be dramatically improved by doping La3+. Moreover, Pr of Pb(Zr0.52Ti0.48)O3 films reaches up to 120.53 µC/cm2, while the doping samples present relatively inferior ferroelectric hysteresis loops (PrLa = 64.32, PrNd = 53.17 µC/cm2), greater dielectric constants, higher dielectric loss and lower leakage current than the undoped Pb(Zr0.52Ti0.48)O3 sample. And meanwhile, the samples showed a typical non-Debye dielectric spectroscopy of multiple quantum relaxation time distribution observing from the Cole–Cole plot at room temperature.