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

Ferroelectric thin films of relaxor-based PbLu0.5Nb0.5O3-PbTiO3 solid solut ion (PLuNT) with compositions near the morphotropic phase boundary were for med by in situ pulsed laser deposition onto La0.5Sr0.5CoO3/(100)MgO (LSCO/M gO). The phase composition of the PLuNT films was sensitive to the depositi on temperature (550-710 degrees C), with single-phase perovskite formation only at 690 degrees C. The perovskite PLuNT films were pseudocubic and epit axial, with (001) planes parallel to the substrate surface. At room tempera ture, capacitors Au/PLuNT/LSCO exhibited ferroelectric behavior (maximum po larization P(m)congruent to 29 mu C/cm(2), remnant polarization P(r)congrue nt to 14 mu C/cm(2), coercive field E(c)congruent to 70 kV/cm), and zero-fi eld dielectric permittivity about epsilon congruent to 300-450. A broad pea k in epsilon was observed around 350 degrees C. With increasing deposition temperature, although the volume fraction of the pyrochlore phase decreased , P-m, P-r, and E-c all decreased, while epsilon remained unchanged. The su ppression of polarization in the capacitors, both compared to that in the P LuNT ceramics and under the variation of the deposition temperature, was ex plained by the presence and evolution of passive layers near the electrodes . (C) 2000 American Institute of Physics. [S0021-8979(00)00520-X].