Pulsed laser deposition of relaxor-based PbLu0.5Nb0.5O3–PbTiO3 thin films

Abstract

Ferroelectric thin films of relaxor-based PbLu0.5Nb0.5O3–PbTiO3 solid solution (PLuNT) with compositions near the morphotropic phase boundary were formed by in situ pulsed laser deposition onto La0.5Sr0.5CoO3/(100)MgO (LSCO/MgO). The phase composition of the PLuNT films was sensitive to the deposition temperature (550–710 °C), with single-phase perovskite formation only at 690 °C. The perovskite PLuNT films were pseudocubic and epitaxial, with (001) planes parallel to the substrate surface. At room temperature, capacitors Au/PLuNT/LSCO exhibited ferroelectric behavior (maximum polarization Pm≅29 μC/cm2, remnant polarization Pr≅14 μC/cm2, coercive field Ec≅70 kV/cm), and zero-field dielectric permittivity about ε≅300–450. A broad peak in ε was observed around 350 °C. With increasing deposition temperature, although the volume fraction of the pyrochlore phase decreased, Pm, Pr, and Ec all decreased, while ε remained unchanged. The suppression of polarization in the capacitors, both compared to that in the PLuNT ceramics and under the variation of the deposition temperature, was explained by the presence and evolution of passive layers near the electrodes.