Mechanism of grain growth and excellent polarization, dielectric relaxtion of La~(3+), Nd~(3+) modified PZT nano-films prepared by sol-gel technique

摘要

Ferroelectric PbZr0.52Ti0.48O3 film and its partial substitutions by rare earth ions La3+ and Nd3+ Pb-0.9(La/Nd)(0.1)Zr0.52Ti0.48O3, 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)O-3 and Pb0.9La0.1(Zr0.52Ti0.48)O-3 films are of (111) preferred orientation but Pb0.9Nd0.1(Zr0.52Ti0.48)O-3 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 d(33) can be dramatically improved by doping La3+. Moreover, Pr of Pb(Zr0.52Ti0.48)O-3 films reaches up to 120.53 mu C/cm(2), while the doping samples present relatively inferior ferroelectric hysteresis loops (Pr-La=64.32, Pr-Nd=53.17 mu C/cm(2)), greater dielectric constants, higher dielectric loss and lower leakage current than the undoped Pb(Zr0.52Ti0.48)O-3 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.