Topic
Dielectric loss
About: Dielectric loss is a research topic. Over the lifetime, 20296 publications have been published within this topic receiving 349254 citations.
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TL;DR: A series of polycrystalline spinel ferrites with composition Co 0.4 Zn 0.6+ X Ti X Fe 2−2 X O 4, were prepared by the standard ceramic method to study the effect of Ti ions substitution on their AC electrical conductivity and dielectric properties at different frequencies and temperatures as discussed by the authors.
106 citations
TL;DR: The investigated polymer has very low conductivity, so this type of polymer can be useful for high-frequency applications, which can reduce the losses caused by eddy current, and for practical use as elements of microwave devices.
Abstract: A pure ferrite and epoxy samples as well as the epoxy/ferrite composites with different 20 wt.%, 30 wt.%, 40 wt.%, and 50 wt.% weight ferrite contents have been prepared by the chemical co-precipitation method. AC-conductivity and dielectric properties such as the dielectric constant and dielectric loss of the prepared samples have been studied. The obtained results showed that the samples had a semiconductor behavior. The dielectric constant of the composites has been calculated theoretically using several models. For the composite sample that contains 20 wt.% of ferrites, these models give satisfactory compliance, while for the composite samples with a higher percentage of nanofillers, more than 30 wt.% theoretical results do not coincide with experimental data. The investigated polymer has very low conductivity, so this type of polymer can be useful for high-frequency applications, which can reduce the losses caused by eddy current. Thus, the prepared samples are promising materials for practical use as elements of microwave devices.
106 citations
TL;DR: In this paper, a series of polycrystalline spinel ferrite with composition CoAl x Fe 2− x O 4, as a function of frequency and temperature, were studied in terms of quantum mechanical tunneling and small polaron tunneling models.
105 citations
TL;DR: If large amplitude time-dependent fields are applied to a sample that displays relaxational modes, some energy of the external field is absorbed by the slow degrees of freedom and implies that dielectric and thermal time constants are locally correlated in viscous liquids.
Abstract: If large amplitude time-dependent fields (e.g., dielectric, magnetic, mechanical) are applied to a sample that displays relaxational modes, some energy of the external field is absorbed by the slow degrees of freedom. The weak coupling of these modes to the phonon bath leads to long persistence times of the resulting higher fictive temperature. Assuming heterogeneities regarding dielectric and thermal relaxation times, extremely strong nonlinear dielectric effects are predicted and experimentally verified. For glycerol at T = 213 K, the dielectric loss measured at 280 kV/cm increases by more than 6% over its low-field value. This nonlinearity shows a characteristic frequency dependence and implies that dielectric and thermal time constants are locally correlated in viscous liquids.
105 citations
TL;DR: In this article, the effect of the Ba/Ti ratio on microstructure, dielectric/ferroelectric properties, and domain width was studied using optical microscopy, ǫ(T) curves, D-E hysteresis, and transmission electron microscopy.
Abstract: The effect of the Ba/Ti ratio on microstructure, dielectric/ferroelectric properties, and domain width was studied using optical microscopy, ɛ(T) curves, D–E hysteresis, and transmission electron microscopy. Although Ti-excess samples showed abnormal grain growth and a decrease of room-temperature permittivity due to a liquid phase at grain boundaries, its ferroelectric properties were similar to those of stoichiometric BaTiO3 ceramics. However, in Ba-excess samples, an increase of permittivity and ferroelectric properties different from those of stoichiometry were found. Changes in domain width and ferroelectric transition behavior indicated that the variation of dielectric properties was related to the internal stress. It is proposed that this internal stress originated from differences in the thermal expansion coefficient between the matrix and the second phase.
105 citations