Influence of crystal structure on the fatigue properties of Pb1-xLax(Zr-y,Ti-z)O-3 thin films prepared by pulsed-laser deposition technique

Abstract

Lead lanthanum zirconate titanate (Pb1-xLax(Zr-y,Ti-z)O-3, PLZT) films containing [00l] preferentially oriented grains were produced successfully on YBa2Cu3O7-x-coated (YBCO-coated) SrTiO3, (STO) or YBCO/CeO2-coated silicon substrates; films containing randomly oriented grains were created on platinum-coated silicon substrates. The latter possessed significantly inferior ferroelectric properties, a fact ascribed to the presence of a paraelectric phase (TiO2,) at the PLZT/platinum interface. On the other hand, the PLZT/YBCO/STO films exhibited better electrical properties than did the PLZT/YBCO/CeO2/Si films, and this phenomenon was attributed to better alignment of the grains in normal and in-plane orientations. In terms of fatigue properties, the [00l] textured films that were deposited on YBCO/CeO2/Si substrates possessed substantially superior polarization-switching-cycle endurance versus the randomly oriented films grown on Pt(Ti)/Si substrates. Moreover, the tetragonal films behaved much more satisfactorily than did the rhombohedral PLZT films. The ferroelectric parameters of tetragonal PLZT films showed no significant degradation up to 10(9) polarization switching cycles, whereas the remnant polarization and coercive force of the rhombohedral PLZT films had already degraded to 80% of their initial values after 10(8) cycles.