On the physical interpretation of constant phase elements

Abouzari, Mohammad Reza Shoar; Berkemeier, Frank; Schmitz, Guido; Wilmer, D.

doi:10.1016/j.ssi.2009.04.002

Cited by 319 publications

(173 citation statements)

References 18 publications

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“…The single depressed semicircle was modelled by a resistance in parallel with a constant phase element (CPE) [40], and the straight line by a resistance in series with the inductance of the wires. For the nano ferrites powders, due to their small size, the intergrain conduction is the predominant phenomenon and only one low frequency semi circle was observed.…”

Section: Conductivitymentioning

confidence: 99%

Magnetic, electric and thermal properties of cobalt ferrite nanoparticles

Ajroudi

Mliki

Bessaïs

et al. 2014

Materials Research Bulletin

135

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Section: Conductivitymentioning

confidence: 99%

Magnetic, electric and thermal properties of cobalt ferrite nanoparticles

Ajroudi

Mliki

Bessaïs

et al. 2014

Materials Research Bulletin

135

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“…Figure 4). n = 1 corresponds to a perfect capacitor, and n < 1 indicates deviations from ideality [20].…”

Section: Electrochemical Testingmentioning

confidence: 99%

Functionally graded composite La 2 NiO 4+δ and La 4 Ni 3 O 10−δ solid oxide fuel cell cathodes

Woolley

Skinner

2014

Solid State Ionics

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Functionally graded electrodes have been fabricated from members of the (LaNiO 3 ) n LaO RuddlesdenPopper family. These consist of a thin compact layer of La 2 NiO 4+δ deposited on the electrolyte, topped by a thicker porous La 2 NiO 4+δ +La 4 Ni 310-δ composite layer, completed by a thin porous La 4 Ni 3 O 10-δ layer acting as a current collector. The microstructure and electrochemical role of these layers is discussed in detail. It was found that using a 50:50 wt.% mix in the composite layer gave the best performance; ASRs at 500, 550, 600, 650, and 700 °C were 15.6, 5.53, 2.29, 1.06 and 0.53 Ωcm 2 respectively. This represents high performance for this class of material, particularly notable at the lower-end of the temperature range. As such this grading process is an attractive proposition for further research towards lowering the operating temperature of SOFCs.

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“…Researchers take different approaches to model this non-ideality by modifying the functional form of impedance parameters through introduction of new circuit elements like constant phase elements (CPEs) [13]. The physical meaning of CPE is poorly understood [14]. Some researchers attribute CPE to the roughness of the electrode-electrolyte interfaces or to the inhomogenieties in the local distribution of defects in the vicinity of grain boundaries [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Frequency dependent electrical properties of Na2Pb2R2W2Ti4Nb4O30 (R = Nd, Sm) ceramics

2014

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Abstract:In the present research work, frequency dependent electrical properties of tungsten bronze structured compounds Na 2 Pb 2 R 2 W 2 Ti 4 Nb 4 O 30 (R = Nd, Sm) are reported. X-ray diffraction (XRD) study of polycrystalline ceramic samples confirms the formation of compounds with orthorhombic structure. Analysis of frequency dependent electrical data in the framework of modulus and conductivity formalism suggests the presence of thermally activated relaxation process in the compounds, which show Arrhenius behavior. The magnitudes of activation energies give the nature of the relaxing species. The real and imaginary parts of complex modulus trace the depressed semicircle in complex plane, suggesting non-Debye type relaxation process in the materials. The power law behavior of admittance data is successfully modeled by introducing constant phase element (CPE) to the equivalent circuit. A large value of power law parameter (n) of CPE below ferroelectric transition temperature (T c ) is attributed to the cooperative response of the dipoles which is reduced above T c . This behavior is correlated with the frequency dependence of CPE, suggesting a physical meaning to it. The frequency dependent AC conductivity at different temperatures follows Jonscher's universal power law. Almond and West formalism is used to estimate the hopping rate, activation enthalpy and charge carrier concentration in the materials.

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On the physical interpretation of constant phase elements

Cited by 319 publications

References 18 publications

Magnetic, electric and thermal properties of cobalt ferrite nanoparticles

Magnetic, electric and thermal properties of cobalt ferrite nanoparticles

Functionally graded composite La 2 NiO 4+δ and La 4 Ni 3 O 10−δ solid oxide fuel cell cathodes

Frequency dependent electrical properties of Na2Pb2R2W2Ti4Nb4O30 (R = Nd, Sm) ceramics

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