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(100)/(001)-oriented 2 μm-thick Pb(Ti, Zr)O3, films with the Zr/(Zr + Ti) ratio of 0.39 and 0.50 were prepared by metalorganic chemical vapor deposition. The volume fraction of (001)-oriented domain, Vc, was controlled by selecting the kinds of substrates with different thermal expansion coefficient. The effective piezoelectric constant increased up to 310 pm/V with decreasing the Vc and tetragonality (lattice parameter ratio of c axis to a axis) determined by the decrease of the Zr/(Zr + Ti) ratio. Observed large piezoelectric response was considered to be mainly contributed by the extrinsic effect, such as the 90o domain switching. These experimental inputs suggest the new concept for enhancement of the piezoelectric properties. [ABSTRACT FROM AUTHOR]

Epitaxial Pb(Zr,Ti)O3 (PZT) thick films of 2.0–3.0 μm thickness were grown at 600 °C on (100)cSrRuO3∥(100)SrTiO3 and (100)cSrRuO3∥(100)LaNiO3∥(100)CaF2 substrates by pulsed-metal organic chemical vapor deposition. All films showed (100) and/or (001) orientations with tetragonal symmetry. It was found that there is an almost linear relationship between the estimated thermal strain from the deposition temperature to the Curie temperature and the volume fraction of (001) orientation in the mixture of (100) and (001) orientations for the films on both substrates. Consequently, the perfectly (001)-oriented, i.e., polar-axis-oriented, PZT thick films were obtained on CaF2 with the Zr/(Zr+Ti) ratio from 0.20 to 0.40. Moreover, the lattice parameter of a- and c-axes and their ratio (c/a) of those polar-axis-oriented films were almost the same as the reported data for the powder, suggesting that the large strain is not remaining in those films. The relative dielectric constant ([variant_greek_epsilon]r) of the polar-axis-oriented Pb(Zr0.35Ti0.65)O3 thick film on CaF2 was 180 at 1 kHz, which is lower than that of (100)/(001)-oriented thick films on SrTiO3 but almost agrees with the theoretically calculated value for the c-axis of PZT single crystals. Well saturated polarization-electric-field hysteresis loops with a good square shape were observed for the polar-axis-oriented thick films, and the saturation polarization and the coercive field values were 74 μC/cm2 and 64 kV/cm, respectively. These data clearly show that the electrical properties of the polar-axis-oriented epitaxial thick films are similar to the theoretical predictions for PZT single crystals. [ABSTRACT FROM AUTHOR]

Epitaxial (100)/(001)-oriented PbTiO3 films with thickness of 2.8 μm were grown on Nb-doped (100) SrTiO3 substrates by pulsed metal organic chemical vapor deposition. Complex domain structures consisting of c-domains (c1) and three types of a-domains (a1, a2, and a3) were observed by piezoresponse force microscopy in conjunction with high-resolution x-ray diffraction analysis. The obtained results suggest that (a2/a3) and (a1/c1) domain configurations represent mostly strain-relaxed structures. This conclusion is in good agreement with theoretical predictions made for thick films [Phys. State., Solidi 37, 329 (1976)]. [ABSTRACT FROM AUTHOR]

(100)/(001)-oriented epitaxial PbTiO3 films thicker than 1 μm were grown on various types of substrates by chemical vapor deposition. The domain structures of these films with different volume fractions of (001) were investigated. Domain structures, consisting of (100)/(001)-oriented domains, were observed regardless of the type of substrate. However, the tilting angles of the a- and c-domains from the surface normal linearly changed with the volume fraction of the (001) orientation. These results suggest that the volume fraction of the (001) orientation is crucial in identifying the domain structure of PbTiO3 thick films. [ABSTRACT FROM AUTHOR]

(100)-/(001)-oriented epitaxial Pb(Zr,Ti)O3 (PZT) films with various Zr/(Zr + Ti) ratios and film thicknesses were grown on (100)cSrRuO3//(100)SrTiO3 substrates at 600°C by metalorganic chemical vapor deposition. Their crystal structure and microstructure consisting of particularly mixed phases with tetragonal and rhombohedral symmetries were investigated in detail. Films with the mixed phases with tetragonal and rhombohedral symmetries were ascertained at a Zr/(Zr + Ti) ratio of around 0.50 at a thickness of more than 200 nm from x-ray diffraction (XRD) analysis, while no mixed phase region was observed for 50 nm thick film. The relative volume fraction of the tetragonal c domain decreased with increasing film thickness for 2 µm thick films with mixed phases, while the tetragonal a domain and rhombohedral domain increased. These mixed phases were ascertained to have originated from the same cubic PZT grown above Curie temperature from results obtained by temperature-dependent high-resolution XRD reciprocal space mapping. The transmission electron microscopy images clearly revealed that the microstructure of the film gradually changed along the film thickness, despite the fact that the film was very uniform. Tetragonal phases were dominant in the bottom region (near the interface with the substrate) of the film, while rhombohedral phase was dominant in the upper region (near the surface), which was also ascertained by cross-sectional Raman analysis. In addition, the tetragonal a/c domain was wider in the bottom region than that in the upper region of film with mixed phases. These data clearly demonstrate that both the crystal structure and microstructure changed along the film thickness. [ABSTRACT FROM AUTHOR]