Test of universal scaling of ac conductivity in ionic conductors

Yebra, Carlos León; Lunkenheimer, P.; Ngai, K. L.

doi:10.1103/physrevb.64.184304

Cited by 40 publications

(27 citation statements)

References 33 publications

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“…These data are presented on a loglog plot for a glass at a composition x = 25% in Figure 5. Permittivity results generally from mobile ions, but the sharp increase in ε' at low frequencies, particularly at f = ω/2π < 10 Hz, is due to electrode polarization effects as Ag + ions are deposited at the anode at very low frequencies 31 . The behaviour is observed for all samples but the magnitude of ε s could be unambiguously determined.…”

Section: Electrical Modulus Analysismentioning

confidence: 99%

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Fast-ion conduction and flexibility and rigidity of solid electrolyte glasses

et al. 2009

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Electrical conductivity of dry, slow cooled (AgPO3)1−x(AgI)x glasses is examined as a function of temperature , frequency and glass composition. From these data compositional trends in activation energy for conductivity EA(x), Coulomb energy Ec(x) for Ag + ion creation, Kohlrausch stretched exponent β(x), low frequency (εs(x)) and high-frequency (ε∞(x)) permittivity are deduced. All parameters except Ec(x) display two compositional thresholds, one near the stress transition, x = xc(1)= 9%, and the other near the rigidity transition, x = xc(2)= 38% of the alloyed glass network. These elastic phase transitions were identified in modulated-DSC, IR reflectance and Raman scattering experiments earlier. A self-organized ion hopping model (SIHM) of a parent electrolyte system is developed that self-consistently incorporates mechanical constraints due to chemical bonding with carrier concentrations and mobility. The model predicts the observed compositional variation of σ(x), including the observation of a step-like jump when glasses enter the Intermediate Phase at x>xc(1), and an exponential increase when glasses become flexible at x>xc(2). Since Ec is found to be small compared to network strain energy (Es), we conclude that free carrier concentrations are close to nominal AgI concentrations, and that fast-ion conduction is driven largely by changes in carrier mobility induced by an elastic softening of network structure. Variation of the stretched exponent β(x) is square-well like with walls localized near xc(1) and xc(2) that essentially coincide with those of the Intermediate Phase (IP) (xc(1)

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Section: Electrical Modulus Analysismentioning

confidence: 99%

“…We now follow the approach developed by Ngai and co-workers 31 and use the electrical modulus formalism to obtain stretched exponents β(x) from our σ(ω) data. Our starting point is to write the electric field E(t) under the constraint of a constant electric displacement as:…”

Section: Electrical Modulus Analysismentioning

confidence: 99%

Fast-ion conduction and flexibility and rigidity of solid electrolyte glasses

et al. 2009

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“…Various scaling laws have been proposed for scaling the AC conductivity data. [39][40][41][42][43] In the present study, Ghosh 42 scaling technique is followed in which the AC conductivity is scaled by the DC conductivity DC and the frequency by the crossover frequency f p which is obtained by fitting conductivity data with…”

Section: Frequency Dependent Ionic Conductivitymentioning

confidence: 99%

Ionic conductivity and relaxation studies in PVDF-HFP:PMMA-based gel polymer blend electrolyte with LiClO₄salt

Gohel

Kanchan

2018

J. Adv. Dielect.

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Poly(vinylidene fluoride-hexafluropropylene) (PVDF-HFP) and poly(methyl methacrylate) (PMMA)-based gel polymer electrolytes (GPEs) comprising propylene carbonate and diethyl carbonate mixed plasticizer with variation of lithium perchlorate (LiClO 4 ) salt concentrations have been prepared using a solvent casting technique. Structural characterization has been carried out using XRD wherein diffraction pattern reveals the amorphous nature of sample up to 7.5 wt.% salt and complexation of polymers and salt have been studied by FTIR analysis. Surface morphology of the samples has been studied using scanning electron microscope. Electrochemical impedance spectroscopy in the temperature range 303-363 K has been carried out for electrical conductivity. The maximum room temperature conductivity of 2.83Â10 À4 S cm À1 has been observed for the GPE incorporating 7.5 wt.% LiClO 4 . The temperature dependence of ionic conductivity obeys the Arrhenius relation. The increase in ionic conductivity with change in temperatures and salt content is observed. Transport number measurement is carried out by Wagner's DC polarization method. Loss tangent (tan ) and imaginary part of modulus (M 00 ) corresponding to dielectric relaxation and conductivity relaxation respectively show faster relaxation process with increasing salt content up to optimum value of 7.5 wt.% LiClO 4 . The modulus (M 00 ) shows that the conductivity relaxation is of non-Debye type (broader than Debye peak).

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“…The electric modulus is defined as the reciprocal of the complex dielectric permittivity (M n ¼ 1/ε n ) and corresponds to the relaxation of the electric field in the system when the electric displacement is constant. Hence the electric modulus, defined by the relation M n ðωÞ ¼ M 0 ðωÞþiM″ðωÞ ¼ ðε 1 Þ À 1 1 À R 1 0 expðÀiωtÞð À dϕðtÞ=dtÞdt Â Ã , can be employed to represent the real dielectric relaxation process in a particular system [38]. In this equation, ε(1) represents the asymptotic value of the real part of the dielectric constant [ε(1)¼ 1/M 0 1 ], and ϕ(t)¼ ϕ(0)exp[À (t/τ) β ], the Kohlrausch-Williams-Watts (KWW) function of the material [39].…”

Section: Resultsmentioning

confidence: 99%