Narrow Results

Bi₂FeCrO₆ thin films were epitaxially grown by pulsed laser deposition on (100)-oriented LaAlO₃, (LaAlO₃)_0.3(Sr₂LaTaO₆)_0.7 and SrTiO₃ single crystalline substrates with and without epitaxial CaRuO₃ buffered layer. The in-plane compressive strain induces monoclinic distortion of the Bi₂FeCrO₆ lattice cell. The strain originates from lattice mismatch between CaRuO₃ and single crystal substrates. The similar crystal structure of the substrate and the layer lead to coherent epitaxial growth of the heterostructures and avoid strain relaxation in particular for BFCO films deposited on LaAlO₃ substrates. The ferroelectric character is demonstrated for all grown BFCO films. The residual in-plane strain weakly affects the effective piezoelectric coefficient of BFCO layers.

Pb(Zr_0.65Ti_0.35)O₃ (PZT) thin films were deposited on SrRuO₃ (SRO) buffer layer coated LaAlO₃ (LAO) substrates by RF sputtering method. X-ray diffraction analyses indicate that the PZT thin films show epitaxial orientation and the in-plane epitaxial relationship between film and substrate is deduced as (001)[010]_PZT‖(001)[010]_SRO‖(001)[010]_LAO. Despite the Zr-richcomposition, observations using transmission electron microscopy reveal that the PZT thin films exhibited tetragonal phase, which was due to the clamping effect of the substrates. The clamping effecton the electrical properties, especially on the dielectric properties, was evaluated. Ferroelectric measurements show that PZT films with LAO/SRO substrates were fatigue-free. However, the test of dielectric property dependences on temperature manifests a relatively low Curie temperature of the PZT films. The loss tangent decreasedwith increase intemperature. Owing to the release of clamping stress, the loss tangent decreased dramatically while the temperature was approaching the phase transition temperature of PZT thin films.