Index of content:
Volume 96, Issue 4, 15 August 2004
- DIELECTRICS AND FERROELECTRICITY (PACS 77)
Structural and electrical characterization of dense lead zirconate titanate ceramics synthesized by the oxidant-peroxo wet-chemical route96(2004); http://dx.doi.org/10.1063/1.1765854View Description Hide Description
Powders wet-chemically synthesized by the “oxidant-peroxo method” with composition were sintered at 1000 and for 2 and , resulting in dense ceramic bodies that were structurally characterized by Raman scattering spectroscopy and by x-ray diffraction at room temperature. Their electrical properties (dielectric constant and dielectric loss) were measured in the temperature range from 25 to at different current frequencies (1, 10, and ). Microstructures were observed using a scanning electronic microscopy equipped with a x-ray energy dispersive spectrometer for chemical analysis. It was observed that the sintered bodies show tetragonal structure, and apparent densities calculated as of the theoretical density.
96(2004); http://dx.doi.org/10.1063/1.1765867View Description Hide Description
It is shown by the example of poly(vinylidene fluoride) that back-switching of ferroelectricpolarization in two-component systems during short circuiting after initial poling depends on the poling time and exhibits a maximum in samples poled for about . The switched back polarization decreases to zero for poling times smaller than and times exceeding . The phenomenon is explained on the basis of a model proposed earlier for polarization buildup in two-component ferroelectrics taking into account the role of conductivity induced interfacial charge accumulation at the boundaries between ferroelectric and nonferroelectric components.
Ferroelectric properties and leakage current characteristics of radio-frequency-sputtered thin films96(2004); http://dx.doi.org/10.1063/1.1766096View Description Hide Description
The ferroelectricproperties and leakage current mechanisms of polycrystalline thin films, which were deposited on substrate by rf-magnetron sputtering and then annealed at for in air, were investigated. These films showed excellent ferroelectricproperties in terms of a large remnant polarization of , fatigue free characteristics up to switching cycles and a low current density of at . X-ray diffraction and scanning electron microscope investigations indicate that the sputteredfilms exhibit a dense, well crystallized microstructure having random orientations and with a rather smooth surface morphology. The improved ferroelectric and leakage currentcharacteristics obtained at the low processing temperature are attributed to the larger polarizability attained through increased rattling space in the distorted of the perovskite block due to the partial substitution of with smaller ions. The leakage current density of the thin films was studied at higher temperatures and the data were fitted with the Schottky and Poole-Frenkel emission models.
96(2004); http://dx.doi.org/10.1063/1.1767968View Description Hide Description
We report on the synthesis of polycrystalline thin films of by the so-called chemical solution deposition technique. The thin films were deposited on substrates by the spin-coating method, and were heat treateded at in air and under several oxygen pressures. The structural, morphological, and ferroelectric properties were characterized by x-ray diffraction , infrared and Raman spectroscopy, atomic force microscopy , and polarization-electric-field hysteresis loop measurements. The and the Raman spectroscopy results revealed that the films heat treated in air and at low oxygen pressures are single phase. However, analysis of the data indicated a clear decreasing of the crystallization degree of the films with increasing oxygen pressure. results showed the films display a rosette structure embedded in a matrix, which comprises grains with an average grain size ranging from 60 to . Ferroelectric hysteresis loops’ measurements performed on these films exhibited a clear decrease of the remnant polarization with increasing oxygen-pressure . This study indicated some important effects of the high oxygen-pressure annealing on the physical properties of thin films.