Effect of Cu ion substitution on structural and dielectric properties of Ni-Zn ferrites

A series of Cu-substituted Ni_(0.5-x)Cu_xZn_(0.5)Fe_2O_4(x=0.12,0.16,0.20,0.24 and 0.28) spinel ferrites were prepared by conventional ceramic method to investigate the effects of Cu compositional variation on the structure and dielectric properties.XRD patterns demonstrate that all the samples are crystallized in single-phase cubic spinel structure and the lattice constant increases with increasing Cu content.White grains observed by SEM are Cu-rich phase.The dielectric constant versus frequency curve displays a normal dielectric behavior of spinel ferrites.While the frequency dependence of dielectric loss tangent is found to be abnormal,exhibiting a peak at certain frequency for all Cu-substituted Ni-Zn ferrites.A maximum of the resistivity is observed at x=0.2 due to the decrease of hopping electrons between Fe^(2+) and Fe^(3+) in per unit volume,which is in contrast with the Cu content dependence of dielectric constant and dielectric loss.

Dynamics of Spatial Dark Solitons Trapped in the Media with Gain and TPA

The propagation of dark solitons in nonlinear media that include gain and Joss described by a nonlinear Schroedinger equation is investigated. Based on the direct approach of perturbation theorv, the width, height and other related quantities of dark solitons are obtained. It is shown that stationarv propagation of dark solitons is found to be possible in the presence of both gain and absorption. The results obtained by means of our analytic method are in excellent agreement with numerical simulations. Our results are helpful for the research into the optical soliton transmission system.

Relationships among group delay,energy storage,and loss in dispersive dielectric mirrors

We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in highly reflective dispersive dielectric mirrors over the high-reflectivity band. Our theoretical considerations are verified by numerical simulations performed on different dielectric mirror structures. The revealed pro- portionality between group delay and absorbed energy sets constraint on the application of ultrabroadband and/or dispersive dielectric mirrors in broadband or widely tunable, high-power laser systems.

Effect of lithium carbonate modification on the ferroelectric phase transition diffusion in lead ferroniobate ceramics

The paper discusses the features of the effect of modification with lithium carbonate on the dielectric dispersion of lead ferroniobate ceramics.The modifier has been previously shown to change the ways of the recrystallization sintering and therefore reduce the sintering temperature of the ceramics,increase their average grain size,and improve their dielectric and piezoelectric properties.In this study,the emphasis is placed on the analysis of the diffusion effects of the ferroelectric phase transition upon such mod-ification considered from the standpoint of the chemical specifics of the modifier and its location in the structure of the parent compound.

Complex permittivity spectra of binary polar liquids using time domain reflectometry

The study of complex properties in a binary mixture of polar liquids has been carried out in the frequency range of 10 MHz to 30 GHz at 293 K and 298 K temperatures using time domain reflectometry.The complex properties of polar liquids in binary mixture give information about the frequency dispersion in the dielectric permittivity(ε')and dielectric loss(ε").The information regarding the orientation of electric dipoles in a polar liquid mixture is given by Kirkwood parameters.The Bruggeman parameters are used as the indicator of liquid1 and liquid2 interaction.Molar entropy(ΔS)and molar enthalpy(ΔH)are also discussed at the end of the paper.