0000000000371202
AUTHOR
J. Levoska
<title>Glass to ferroelectric phase transition induced by ac electric field in PbMg<formula><inf><roman>1/3</roman></inf></formula>Nb<formula><inf><roman>2/3</roman></inf></formula>O<formula><inf><roman>3</roman></inf></formula> thin films</title>
The nonlinear dielectric response of epitaxial heterostructures of relaxor ferroelectric PbMg1/3Nb2/3O3 thin films was experimentally studied using digital Fourier analysis. The amplitudes and the phase angles of the dielectric harmonics were determined as a function of temperature and the amplitude of the sinusoidal ac field. The response of the films was reconstructed assuming a linear contribution of the film-electrode interface capacitance. In the films at low amplitudes of ac field, a glass-like behavior was identified by a maximum in the third-order nonlinear dielectric permittivity around the freezing temperature, accompanied by a square field dependence of the amplitudes of the odd …
Structure and properties of epitaxial ferroelectric PbLu0.5Nb0.5O3thin films
Abstract Epitaxial thin film heterostructures of PbLu0.5Nb0.5O3 (PLuN) and La0.5Sr0.5CoO3 (LSCO) were deposited by in situ pulsed laser ablation onto MgO and LaAlO3 (100) substrates. The formation of crystalline phases, epitaxy, film-electrode-substrate orientation relationships, crystal perfection and chemical order were studied by x-ray diffraction. The structural properties were found to depend on the deposition conditions and on the substrate. The perovskite PLuN films were pseudocubic and epitaxial, with (001) planes parallel to the substrate surface. At room temperature, Au/PLuN/LSCO capacitors exhibited ferroelectric behavior and zero-field dielectric permittivity about e ≅ 210–260, …
Compositional Evolution of Properties in Epitaxial Films of Relaxor PbMg1/3Nb2/3O3-PbTiO3
Epitaxial heterostructures of relaxor (1− x) PbMg1/3Nb2/3O3−(x) PbTiO3 thin films with La0.5Sr0.5CoO3 bottom electrodes were grown by pulsed laser ablation on MgO substrates. Perovskite films with x = 0–0.32 were deposited using sub-monolayer mixing from two targets. Both the room-temperature studies of microstructure and studies of dielectric response as a function of frequency and temperature were performed. For all x, a relaxor-like behavior was observed. The compositional evolution of lattice parameter, permittivity, and temperature of dielectric maxima T m was in a qualitative agreement with that in bulk. The relatively low temperatures T m in the presence of an in-plane compression we…
Ferroelectric Behavior in Epitaxial Films of Relaxor PbMg1/3Nb2/3O3
The nonlinear dielectric response of epitaxial thin films of relaxor ferroelectric PbMg1/3Nb2/3O3 was experimentally studied using digital Fourier analysis. Change from glass-like to ferroelectric behavior was detected in a broad temperature range, at relatively low ac and/or dc electric fields, and at a time scale of seconds. The presence of interfaces and peculiar microstructure of thin films are suggested to determine such a specific behavior.
Epitaxial Films of Relaxor Ferroelectric PbMg1/3Nb2/3O3in Strong Electric Fields
Epitaxial thin films of perovskite relaxor ferroelectric PbMg 1/3 Nb 2/3 O 3 were grown on MgO (001) substrates by pulsed laser deposition using La 0.5 Sr 0.5 CoO 3 bottom electrode layers. Dielectric response of the films was experimentally studied as a function of temperature and frequency in a broad range of amplitudes of ac electric field (to 10 MV/m) and magnitudes of dc electric field (to 50 MV/m). At small fields, a glass-like behavior was observed. With increasing magnitude of the dc field, an onset of a polar state was detected. The orientation of the polar clusters along the direction of the field and fluctuations of the direction of their dipole moments were suggested to determin…
Structural characterization of relaxor ferroelectric PbMg 1/3 Nb 2/3 O 3 -PbTiO 3 thin film heterostructures deposited by pulsed laser ablation
Highly oriented and epitaxial films of relaxor ferroelectric PbMg1/3Nb2/3O3-PbTiO3 (PMN-PT) with a composition (68/32) near the morphotropic phase boundary were deposited by pulsed laser ablation on La0.5Sr0.5CoO3 bottom electrodes, deposited on MgO (100) and LaAlO3 (100). The formation of crystalline phases, epitaxy, film–electrode–substrate orientation relationships and crystal perfection were studied by X-ray diffraction and scanning electron microscopy. The structural properties were found to depend on the deposition conditions and substrate. Correlation of both the dielectric and relaxor properties in the heterostructures and the structural properties of the PMN-PT films was observed.
Pulsed laser deposition of relaxor ferroelectric films
Heterostructures of perovskite relaxor ferroelectric (RFE) thin films onto La 0.5 Sr 0.5 CoO bottom electrode layers were grown by pulsed laser deposition on MgO(100) crystal substrates. The films were highly oriented, with (h00) planes parallel to the substrate surface, and demonstrated good dielectric and ferroelectric quality at room temperature. The studies of the dielectric properties of the films over the frequency range of 20 Hz....100 kHz and over the temperature range of 0...350°C revealed relaxor type behavior in the films. A diffuse ferroelectric phase transition and a shift of the maximum dielectric permittivity towards higher temperatures with increasing frequency were observed…