Polarization Dynamics in La5/3Sr1/3NiO4

1999 ◽  
Vol 602 ◽  
Author(s):  
N. Hakim ◽  
Z. Zhai ◽  
C. Kusko ◽  
P.V. Parimi ◽  
S-W. Cheong ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Dielectric Response ◽  
Charge Ordering ◽  
Dielectric Susceptibility ◽  
Dynamic Susceptibility ◽  
Loss Peak ◽  
Relaxation Rates ◽  
Relaxation Mode ◽  
Microwave Frequencies ◽  
Charge Stripe

AbstractDynamic susceptibility measurements at microwave frequencies (2 – 10GHz) are a sensitive probe of charge dynamcis in La5/3Sr1/3NiO4. Below the charge ordering temperature of 240K, a dielectric loss peak due to a relaxation mode with a large dielectric susceptibility is observed, and is associated with charge stripe formation. The dielectric response for Hω∥b (Eω ⊥ b) is well represented by ε(T) = εo/(1 – iωτ(T)), with εo, ∼ 50, and τ(T) = 2 × 10−9(sec) exp(−T/37K). Parallel conductivity σ(T) contributions dominate at higher temperatures and for Hω∥c (Eω ⊥ c). The dielectric loss peak observed indicates that the charge relaxation rates lie in the GHz frequency ranges.

scholarly journals Hopping Model for the Non-Debye Dielectric Response in Ionic Crystals

1988 ◽  
Vol 135 ◽  
Author(s):  
J. C. Wang ◽  
J. B. Bates
Keyword(s):  
Dielectric Loss ◽  
Phase Angle ◽  
Dielectric Response ◽  
Activation Energies ◽  
Interesting Property ◽  
Ionic Crystals ◽  
Loss Peak ◽  
Increasing Temperature ◽  
Double Wells ◽  
Hopping Model

AbstractA model based on ion hopping in potential double-wells is proposed to explain the non-Debye dielectric response in solids. Relying on some assumptions, an attempt is made to remove the “average” nature of previous diffusion theories. This results in a distribution of activation energies, G(E), which decays exponentially on both sides of some given value E0. It is shown that (a) the existence of a dielectric loss peak is a result of the decay of G(E) for E > E0, (b) the constant-phase-angle behavior above the loss peak is associated with the decay of G(E) for E < E0, and (c) G(E) can produce all the main features of the empirical Havriliak-Negami function. An interesting property of this G(E) is that it broadens with increasing temperature, consistent with many experimental observations.

High Frequency Dielectric Response of the Ionic Liquid N-Methyl-N-ethylpyrrolidinium Dicyanamide

2007 ◽  
Vol 60 (1) ◽  
pp. 6 ◽  
Author(s):  
Simon Schrödle ◽  
Gary Annat ◽  
Douglas R. MacFarlane ◽  
Maria Forsyth ◽  
Richard Buchner ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
High Frequency ◽  
Dielectric Response ◽  
Room Temperature ◽  
Room Temperature Ionic Liquid ◽  
Dielectric Relaxation Spectroscopy ◽  
Frequency Range ◽  
Fast Rotation

A study of the room-temperature ionic liquid N-methyl-N-ethylpyrrolidinium dicyanamide by dielectric relaxation spectroscopy over the frequency range 0.2 GHz ≤ ν ≤ 89 GHz has revealed that, in addition to the already known lower frequency processes, there is a broad featureless dielectric loss at higher frequencies. The latter is probably due to the translational (oscillatory) motions of the dipolar ions of the IL relative to each other, with additional contributions from their fast rotation.

Relaxation of Dielectric Loss Peak over Intermediate Temperature Range in Bi 5 TiNbWO 15 Intergrowth

2009 ◽  
Vol 26 (4) ◽  
pp. 047701 ◽  
Author(s):  
Wang Wei ◽  
Wang Xiao-Juan ◽  
Zhu Jun ◽  
Mao Xiang-Yu ◽  
Chen Xiao-Bing
Keyword(s):  
Dielectric Loss ◽  
Intermediate Temperature ◽  
Loss Peak ◽  
Temperature Range ◽  
Intermediate Temperature Range

AC Loss Modeling in Ba0.5Sr0.5TiO3 Using Dielectric Relaxation

2004 ◽  
Vol 833 ◽  
Author(s):  
Nadia K. Pervez ◽  
Jiwei Lu ◽  
Susanne Stemmer ◽  
Robert A. York
Keyword(s):  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
Power Law ◽  
Fractional Power ◽  
Ac Loss ◽  
Dielectric Susceptibility ◽  
Network Analyzer ◽  
Q Factor ◽  
Relaxation Model ◽  
Q Factors

ABSTRACTIn universal relaxation, a material's complex dielectric susceptibility follows a fractional power law f1-n where 0 < n < 1 over multiple decades of frequency. In a variety of materials, including Ba0.5Sr0.5Ti03, dielectric relaxation has been observed to follow this universal relaxation model with values of n close to 1. In this work we have shown that the universal relaxation model can be used to calculate dielectric loss even when n is very close to 1. Our calculated Q-factors agree with measured values at 1 MHz; this agreement suggests that this technique may be used for higher frequencies where network analyzer measurements and electrode parasitics complicate Q-factor determination.

scholarly journals Charge order lock-in by electron-phonon coupling in La1.675Eu0.2Sr0.125CuO4

2021 ◽  
Vol 7 (27) ◽  
pp. eabg7394
Author(s):  
Qisi Wang ◽  
Karin von Arx ◽  
Masafumi Horio ◽  
Deepak John Mukkattukavil ◽  
Julia Küspert ◽  
...  
Keyword(s):  
Wave Vector ◽  
Charge Order ◽  
Charge Ordering ◽  
Electron Interaction ◽  
Phonon Coupling ◽  
Electron Phonon Interaction ◽  
Self Energy ◽  
Electron Phonon Coupling ◽  
Charge Stripe ◽  
Lock In

Charge order is universal to all hole-doped cuprates. Yet, the driving interactions remain an unsolved problem. Electron-electron interaction is widely believed to be essential, whereas the role of electron-phonon interaction is unclear. We report an ultrahigh-resolution resonant inelastic x-ray scattering (RIXS) study of the in-plane bond-stretching phonon mode in stripe-ordered cuprate La1.675Eu0.2Sr0.125CuO4. Phonon softening and lifetime shortening are found around the charge ordering wave vector. In addition to these self-energy effects, the electron-phonon coupling is probed by its proportionality to the RIXS cross section. We find an enhancement of the electron-phonon coupling around the charge-stripe ordering wave vector upon cooling into the low-temperature tetragonal structure phase. These results suggest that, in addition to electronic correlations, electron-phonon coupling contributes substantially to the emergence of long-range charge-stripe order in cuprates.

Multi-Component Mixture Modeling for the Dielectric Properties of Rubber Wood at Microwave Frequencies

Holzforschung ◽  
1999 ◽  
Vol 53 (6) ◽  
pp. 662-668 ◽  
Author(s):  
K.B. Khalid ◽  
M.F. Kabir ◽  
W. M. Daud ◽  
H.A.A. Sidek
Keyword(s):  
Experimental Data ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Factor ◽  
Dielectric Constants ◽  
Dielectric Loss Factor ◽  
Component Mixture ◽  
Microwave Frequencies ◽  
Conductive Loss ◽  
Rubber Wood

Summary Dielectric properties from 1 to 18 GHz of rubber wood are modeled using generalized mixture equations and also with equations proposed by Weiner, Kraszewski, Looyenga and Landou, Lichtenecker. Dielectric properties were measured with an open-ended coaxial line-sensor in three structural directions longitudinal, radial and tangential and at different moisture contents. The dielectric constants were predicted well by the Weiner model for all structural grain directions and it was found that the degree of binding decreases with increasing frequency. However, the Weiner model cannot be used for predicting the dielectric loss factor at frequencies below 3 GHz. This may be due to the high conductive loss in this frequency region. The lower value of the exponents in generalized mixture equation was found suitable for fitting the experimental data as well as the Kraszewski equation. Values predicted by Lichtenecker equations are in well agreement with the experimental data at higher microwave frequencies. The prediction of dielectric loss factor using Kraszewski, Looyenga equations were not possible at frequencies below 3 GHz since it is dominated by conductive loss. Above 3 GHz, it was well predicted by Kraszewski and Looyenga equations.

Synthesis and dielectric properties of barium tantalates and niobates with complex perovskite structure

2002 ◽  
Vol 17 (12) ◽  
pp. 3182-3189 ◽  
Author(s):  
T. Kolodiazhnyi ◽  
A. Petric ◽  
A. Belous ◽  
O. V'yunov ◽  
O. Yanchevskij
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Point Defects ◽  
Cation Ordering ◽  
Second Phase ◽  
Extrinsic Factors ◽  
Paramagnetic Resonance ◽  
Microwave Frequencies ◽  
Disorder Phase Transition ◽  
Complex Perovskites

Phase composition, degree of cation ordering, and dielectric properties of complex perovskites with general formula Ba(B' 1/3B"2/3)O3, where B′ = Mg, Zn, and Ni and B" = Nb and Ta, were analyzed. It was found that all the studied complex perovskites attained high degrees of 1:2 cation ordering at temperatures specific to each composition. A high temperature order–disorder phase transition in Ba(Zn1/3Nb2/3)O3 occurred below 1380 °C. Ba(Ni1/3Nb2/3)O3 (BNN) and Ba(Mg1/3Nb2/3)O3 (BMN) pervoskites remained 100% ordered at temperatures as high as 1500 and 1620 °C, respectively. It was found that in BMN and BNN extrinsic factors, such as the second phase (i.e., Ba3Nb5O15) and point defects, dominated the dielectric loss at microwave frequencies. Ba(Mg1/3Ta2/3)O3 (BMT) remained single phase up to 1630 °C. Above this temperature, the Ba3Ta5O15 second phase was detected. A decrease in the 1:2 cation ordering and increase of dielectric loss in BMT occurred at sintering temperatures above 1590 °C. It was also revealed by electron paramagnetic resonance that all samples studied contained a substantial amount of paramagnetic point defects. These defects contributed to extrinsic dielectric loss at microwave frequencies, thus degrading the Q factor.

Dielectric Dispersion Studies of Some Intramolecular Hydrogen Bonded Molecules at Microwave Frequencies

1977 ◽  
Vol 32 (6) ◽  
pp. 604-606 ◽  
Author(s):  
H. D. Purohit ◽  
S. Kumar ◽  
A. D. Vyas
Keyword(s):  
Dielectric Loss ◽  
Complex Plane ◽  
Dipole Moments ◽  
Dielectric Dispersion ◽  
Dielectric Relaxation Time ◽  
Relaxation Processes ◽  
Microwave Frequencies ◽  
Group Rotation ◽  
Intramolecular Hydrogen ◽  
Straight Lines

Abstract The permittivity and dielectric loss of acetyl acetone, benzoyl acetone and dibenzoyl methane have been measured at four microwave frequencies viz., 30.20, 24.50, 18.26, and 9.83 GHz and also at 1 MHz and optical frequency at 35 °C. The permittivity and dielectric loss at different frequen­ cies have been plotted against concentration (wt. fraction). The slopes of these straight lines have been used for the complex plane plots (a″ vs. a′). The complex plane plots for these compounds are Cole-Cole arcs. The dielectric relaxation time (τ0) and distribution parameter (α) have been calculated from these plots. Data have been analysed in terms of two relaxation processes i. e., cor­ responding to overall rotation and group rotation. The dipole moments of these molecules are reported.

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