Features Of Dielectric Response Research Articles

Dielectric response features and oxygen migration on rare earth modified lead titanate ferroelectric ceramics

Rare earth (RE) and manganese-modified lead titanate ceramics were studied concerning the presence of two peaks in the temperature dependence of the dielectric permittivity. An eventual incorporation of the RE into A-site and/or B-site in the perovskite structure and the oxygen migration were considered as causes of the observed phenomenon. The structural analysis showed that at least a small amount of Ti4+ could be substituted by the RE ions. It was considered from the pyroelectric and electrical conductivity results that, even when an eventual incorporation of the RE into the A-site and/or B-site of the structure could be possible, both peaks could not be associated with paraelectric–ferroelectric (PE-FE) phase transitions. The observed peak at lower temperatures has been associated with the PE-FE phase transitions, whereas the hopping of oxygen vacancies has been considered as the cause for the dielectric anomaly observed at higher temperatures.

Features of dielectric response in PMN–PT ferroelectric ceramics

In this paper, electrical and structural properties were reported for pyrochlore free (1 − x)[Pb(Mg1/3Nb2/3)O3] − xPbTiO3 (PMN–PT) (with 35 mol% PbTiO3) ceramics obtained from fine powders. Dielectric studies were focused on the investigation of the complex dielectric permittivity (ε′ − iε″) as a function of frequency and temperature. The effects of the dc applied electric field on dielectric response were also investigated. Results revealed a field dependence dielectric anomaly in the dielectric permittivity curves (ε(T)) in the low dc electric field region, which in turn prevails in the whole analysed frequency interval. To the best of our knowledge, these properties for the PMN–PT ceramic system have not been reported before as in this work. The results were analysed within the framework of the current models found in the literature.

Specific features of dielectric response in PZT ferroelectric films

Reverse dependences of the permittivity e′(E =) of Pb(Ti0.45Zr0.53W0.01Cd0.01)O3 ferroelectric films prepared by high-frequency magnetron sputtering on a stainless steel substrate have been studied. The e′(E =) dependences and the polarization loops are compared. The mechanisms responsible for the specific features of the dielectric response in the films under study are discussed.

Nonlinearity of Dielectric Parameters of PbNi 1/3 Nb 2/3 O 3 -Pb(Zr,Ti)O 3 Ferroelectric Solid Solutions

Reversible dielectric permeability l ' r (E = ) of 0.5PbNi 1/3 Nb 2/3 O 3 - 0.5Pb(Zr,Ti)O 3 ferroelectric ceramics is studied at different lead titanate to zirconate ratios. Particular features of dielectric response - fractures and small plateaux on the l ' r (E = ) curve are observed at some values of the bias field E = . The anomalies are explained by phase transformations induced by applied field and suggest of broadening of the morphotropic phase boundary in the system.

Correlation of large dielectric response with the ordering transitions inPr0.67Ca0.33MnO3

Frequency-dependent capacitance measurements and transport measurements tuned to reveal system impedance have been performed on epitaxial thin films of ${\mathrm{Pr}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}.$ These reflect strong dielectric response features correlated to the various ordering transition temperatures in the system, namely, \ensuremath{\sim}220 K (charge ordering), \ensuremath{\sim}130 K (antiferromagnetic ordering), and \ensuremath{\sim}117 K (spin canting). An equally strong feature is also seen at \ensuremath{\sim}125 K, which does not correspond to any reported transition. The enhanced dielectric response at the transitions is attributed to the nonequilibrium transport and slow carrier reorganization dynamics defined by polaronic hopping and magnetic frustration.

Fractal features of dielectric response of ferroelectrics with domains and clusters

The character of low-infralow-frequency dielecric spectra of typical ferroelectrics, their transformation with temperature, electric field intensity and aging, the temperature dependences of relaxation times in phase transition proximities give evidence of the fractality of the ferroelectrics with domains and clusters.