Phase development and electrical property analysis of pulsed laser deposited Pb(Mg1/3Nb2/3)O3-PbTiO3 (70/30) epitaxial thin films

(001)-oriented heterostructures consisting of LaAlO3 substrates, SrRuO3 bottom electrodes, and Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) (70/30) films were deposited by pulsed laser deposition from Pb-enriched ceramic targets. The epitaxial growth of all layers was confirmed by four-circle x-ray diffraction. Film growth was carried out over a wide range of processing space where substrate temperature, ambient pressure, and laser parameters were varied in order to determine suitable conditions for producing high quality crystals with good electrical properties. In general, strong similarities were observed between thin film and ceramic processing of the same compositions. The associated pyrochlore phase was very difficult to avoid and, in the absence of excess Pb-containing second phases, could only be done at very high temperatures and high oxygen/ozone pressures for films on LaAlO3 substrates. When deposited at temperatures below approximately 640 degrees C, PMN-PT films grown from lead-enriched targets exhibited depressed ferroelectric transition temperatures. For depositions at or above 660 degrees C, the electrical properties approached those of bulk single crystals. In particular, films showed room temperature dielectric constants greater than 1500, well developed Curie-Weiss behavior, and remanent polarization values between 13 and 20 mu C/cm(2). (C) 1998 American Institute of Physics. [S0021-8979(98)08520-X].