Distribution Function Of Relaxation Times Research Articles

Electrostatic spray deposited Ca3Co4O9+δ and Ca3Co4O9+δ/Ce0.9Gd0.1O1.95 cathodes for SOFC: A comparative impedance analysis study

Mixed conducting Ca3Co4O9+δ (CCO) is an interesting cathode material for application in Solid Oxide Fuel Cells (SOFC). In a previous study it has been shown that addition of Ce0.9Gd0.1O1.95 (CGO) significantly enhances the electrode properties, reducing the Area Specific Resistance (ASR) to ~0.5 Ω cm2 at 700°C for the CCO/CGO 50/50% composition. As the microstructure of a composite electrode has a significant influence on the frequency dispersion, it is of interest to prepare electrodes with quite different microstructures. Electrostatic Spray Deposition (ESD) is a technique that is able to produce a large variety of microstructures by modifying the process parameters. Very different microstructures can help in elucidating the major charge transport and transfer processes in an electrode.In this study pure CCO and a CCO/CGO composite (50/50%), both prepared with ESD, are compared and analyzed with Electrochemical Impedance Spectroscopy (EIS). The analysis of the ESD-CCO/CGO composition showed remarkable similarities with the screen-printed cathodes from the previous study, although a clear change in the magnitudes of the separate contributions (low-frequency redox, mid-frequency Gerischer and high-frequency diffusion) was observed. The ASR was close to the screen-printed one, but showed two apparent activation energies in the Arrhenius graph. A tentative model indicates that the Gerischer process is related to dissociative oxygen adsorption and (surface) diffusion at the CGO phase. The limiting factor is the density of the triple-phase boundaries (TPBs) between CCO, CGO and the ambient, which is for the ESD-CCO/CGO cathode apparently lower than for the microstructure of the screen-printed cathodes. It was noted that for the ESD-CCO/CGO cathodes the Distribution Function of Relaxation Times (DFRT) presented a more consistent image of the temperature dependence than the standard Complex Nonlinear Least Squares (CNLS) analysis.The pure ESD-CCO cathode showed a remarkable dispersion, which could be interpreted with a Finite Length Warburg (FLW) model. Although analysis with a simple Equivalent Circuit (EqC) was not feasible, partial CNLS-analysis of the high- and low-frequency regimes resulted in a parameter set that is consistent with the FLW-model. Considering the coral-like microstructure, the oxygen reaction at the electrode could be interpreted as slow oxygen dissociation and fast diffusion towards a more dense CCO layer at the electrolyte interface, followed by a fast oxygen exchange step at the CCO-layer/platelets + ambient interface. Combining FLW parameters with published chemical diffusion values, an apparent effective layer thickness of 2.2 μm could be estimated.

Tri-Functional Double Perovskite Oxide Catalysts for Fuel Cells and Electrolyzers.

Perovskite oxides are at the forefront of the race to develop catalysts/electrodes for fuel cells and electrolyzers. This work presents trifunctional properties of the double-perovskite oxide PrBa0.5 Sr0.5 Co1.5 Fe0.5 O5+δ and the PrBa0.5 Sr0.5 Co1.5 Fe0.5 O5+δ -Ag composite prepared by the glycine nitrate process. The electrocatalytic studies reveal that the Ag-based composite is an excellent catalyst for both oxygen evolution (OER) and hydrogen evolution reactions (HER) in alkaline solution. The electrochemical impedance spectroscopy analysis through distribution function of relaxation times (DFRT) suggests that the improved activity originates from the suppression of resistance contributed by various relaxation processes. The oxygen reduction reaction (ORR) kinetics in these oxide-based cathodes has been studied by performing symmetric-cell measurements at high temperatures using both oxygen-ion and proton-conducting cells. DC bias dependence of charge-transfer processes, oxygen-surface kinetics, polarization resistances, and activation energies are revealed by DFRT studies. Ag addition in PrBa0.5 Sr0.5 Co1.5 Fe0.5 O5+δ leads to enhanced kinetics of OER, HER, and ORR.

Study on enthalpy relaxation of glassy polystyrene using Kohlrausch, Davidson-Cole and Havriliak-Negami distribution functions

The heat capacity data of PS after cooling at different rates were analyzed using heterogeneous kinetic model by combining exponential decay equation with various relaxation time distribution functions instead of the conventional method of combining the stretched relaxation function with Boltzmann superposition. It is found that the shape of the calculated heat capacity peak is highly correlated to the shape of the relaxation time distribution function. The fitting quality of the Davidson-Cole distribution function is worse compared with that of Kohlrausch distribution function. When the mirror functions of Kohlrausch and Davidson-Cole are used, the fitting quality improved greatly. The result indicates that relaxation kinetic of polymer may be described better by combining appropriate relaxation time spectrum with relaxation time model. This approach affords the possibility of taking the temperature and structure dependence of Kohlrausch exponent into consideration in the kinetic study of polymer in non-isothermal relaxations.

Modeling of the impedance data of gadolinia doped ceria based actuators: a distribution function of relaxation times and machine learning approach

Gadolinia-doped ceria is one of the most extensively examined oxide ion conductors to exhibit large nonclassical electrostriction. The electromechanical response depends on the grain and grain boundaries which can be probed using electrochemical impedance spectroscopy. In this study, we have modeled the impedance spectra from buckled and free standing gadolinia doped ceria (Gd0.2Ce0.8O1.9) membrane in Al/Ti/Gd0.2Ce0.8O1.9/Ti/Al electromechanical device, at different AC excitation voltages (2, 4, 6, 8 and 10 V), and starting from room temperature to 100 °C. The analysis of impedance spectrum is commonly done by equivalent circuit modeling to obtain the resistors () and capacitors (). However, to overcome the inherent problems like non-uniqueness, over fitting, presently different approaches have been chosen such as impedance spectroscopy genetic programming (ISGP) and artificial neural networks (ANNs). ISGP finds an analytic form of the distribution function of relaxation times (DFRTs) using impedance spectra. The DFRT analysis reveals that the grain boundary capacitance for the membrane ∼10−8–10−9 F decreases with increasing temperature and excitation voltages. Besides, neural networks, which are optimized by Bayesian regularization, simulate both the real and imaginary parts of impedance following the pattern of experimental data up to several Hz. The DFRT analysis on this simulated impedance data shows an effect of grain boundaries. Indeed, ANNs as optimized by Levenberg-Marquardt method, can estimate the and ’s for present system with maximum relative errors of 24% and 22%, respectively.

On a variation of the Tikhonov regularization method for calculating the distribution function of relaxation times in impedance spectroscopy

In a recent paper of Zhang et al. (2016) a variation of the Tikhonov regularization method for calculating the distribution of relaxation times (DRT) in relation to analysis of the electrochemical impedance spectroscopy data has been proposed. The novelty of the proposed method is that it is free from the regularization parameter, the adjusting of which usually causes the main issue when applying the Tikhonov regularization method. In the present paper, we investigate by means of numerical experiments the frequency resolution of the method by Zhang et al. and its robustness to resist noise embedded in the impedance spectra. In doing so, we also consider how changing certain matrices used in the method affects the results. In addition, the DRT function calculation for a real electrochemical object by means of this new approach is shown.

Some features of the analysis of broadband impedance data using distribution of relaxation times

The article discusses the preparation of the data of electrochemical impedance spectroscopy (EIS) for representation in the form of distribution of relaxation times (DRT). In the case of broadband EIS, the measurement errors are not normally distributed and, herewith, cannot be modeled by white Gaussian noise. This circumstance is essential because the DRT method is hugely susceptible to measurement errors. It is shown, that considering the variation of the measurement errors across the frequency range improves the quality of the DRT function. Thus due to a comprehensively optimized problem, the DRT may provide a better resolution of distinct charge relaxation processes than the conventional equivalent circuits. The Python application was written for the calculation of nonparametric DRT function, and the actually measured impedance data of solid electrolytes and RC circuits were used to illustrate the methodology of the calculation. The application uses least-square solver for non-negative solutions along with Tikhonov regularization. All the experience gained by using the prior version of the app, written in Matlab, is built into the new product. Some aspects of the selection of regularization parameter by using, so-called, L-curve is also discussed.

Characterization and polarization DRT analysis of direct ethanol solid oxide fuel cells using low fuel partial pressures

Commercial Ni-YSZ anodes of solid oxide fuel cells (SOFCs) are susceptible to carbon deposits using hydrocarbons as fuel. Herein, we explore a simple approach of low fuel partial pressure to investigate the relevant limiting factors for ethanol-fueled SOFCs, providing the evaluation of the electrochemical performance and the carbon tolerance. As the partial pressure of ethanol fuel increases from 30% to 60%, the best cell performance gradually increases from 710.2 mW cm−2 to 856.8 mW cm−2 at 800 °C, which still lower than those of hydrogen-fueled SOFCs (1061.4 mW cm−2 at 800 °C), and the corresponding improvement in concentration polarization can be clearly observed especially in high current discharge area. The corresponding impedance spectra and electrode polarization processes of ethanol-fueled SOFCs are further studied by the equivalent circuit fitting and the distribution function of relaxation time (DRT) analysis, finding that the key improvement of the speed control steps comes from the concentration polarization process with the increase of the fuel partial pressure. Small amount of carbon deposition is observed on the Ni-YSZ anode substrate by SEM-EDS images after short-term discharging testing, and the safety utilization boundaries of ethanol-fueled SOFCs with a certain steam concentration can be predicted by the thermodynamic equilibria calculation.

Electrochemical impedance spectra of RuO2 during oxygen evolution reaction studied by the distribution function of relaxation times

In this work, the distribution function of relaxation times (DFRT) of a RuO2 catalyst is determined by Impedance Spectroscopy Genetic Programming (ISGP). The resulting DFRT plots contain three peaks that vary with the overpotential. This discloses the presence of various electrochemical phenomena at different relaxation times in the catalyst. The effective resistance to charge transfer during the oxygen evolution reaction (OER) is small at low overpotential but becomes dominant at high overpotential. Moreover, we can track the change in each peak after a stability test: the resistance to both the production rate of intermediates and charge transfer show an increase while the solution resistance is almost constant. Hence, ISGP opens a new avenue for analyzing catalysts and providing detailed information about the resistance contributed by various phenomena.

Adaptive multi-parameter regularization approach to construct the distribution function of relaxation times

Determination of the distribution function of relaxation times (DFRT) is an approach that gives us more detailed insight into system processes, which are not observable by simple electrochemical impedance spectroscopy (EIS) measurements. DFRT maps EIS data into a function containing the timescale characteristics of the system under consideration. The extraction of such characteristics from noisy EIS measurements can be described by Fredholm integral equation of the first kind that is known to be ill-posed and can be treated only with regularization techniques. Moreover, since only a finite number of EIS data may actually be obtained, the above-mentioned equation appears as after application of a collocation method that needs to be combined with the regularization. In the present study, we discuss how a regularized collocation of DFRT problem can be implemented such that all appearing quantities allow symbolic computations as sums of table integrals. The proposed implementation of the regularized collocation is treated as a multi-parameter regularization. Another contribution of the present work is the adjustment of the previously proposed multiple parameter choice strategy to the context of DFRT problem. The resulting strategy is based on the aggregation of all computed regularized approximants, and can be in principle used in synergy with other methods for solving DFRT problem. We also report the results from the experiments that apply the synthetic data showing that the proposed technique successfully reproduced known exact DFRT. The data obtained by our techniques is also compared to data obtained by well-known DFRT software (DRTtools).

Investigation of Fe-substituted in BaZr0.8Y0.2O3-δ proton conducting oxides as cathode materials for protonic ceramics fuel cells

Cathode materials containing proton conductivity for protonic ceramics fuel cells (PCFCs) can increase the three phase boundary length of the air/cathode/electrolyte, and thus increase the reaction rate of proton with oxygen-species to form water in cathode side. In this work, a serious of Fe-substituted in BaZr0.8Y0.2O3-δ proton conducting oxides, abbreviated as BaZr0.8-xFexY0.2O3-δ (BZFY-2, BZFY-4, BZFY-6, BZFY-8), were synthesized and investigated as cathode materials for PCFCs, considering the phase structure, mean valence state and electrochemical performance. Accordingly, anode supported button cells using BaZr0.8-xFexY0.2O3-δ as cathodes are fabricated, and then performed from 700 to 550 °C. The cell performance with BZFY-6 presents optimal electrochemical performance with different Fe doping amount, and the peak power density of 322.23 mW cm−2 and the corresponding polarization resistance of 0.28 Ω cm2 are observed at 700 °C. Moreover, the corresponding electrode polarization processes are further studied by the distribution function of relaxation time (DRT) analysis, and three peaks of P1, P2 and P3 in DRT curves correspond the proton bulk diffusion, electrochemical reaction processes, and adsorption as well as diffusion process of oxygen, respectively. Preliminary results demonstrate that BZFY-6 can be a competitive promising for PCFCs.

Phase transformations in La2-xYxMo2O9 (x = 0.05, x = 0.075): Temperature cycling and DRT analysis

Two members of ceramic samples of the so-called LAMOX family oxygen ionic conductors La2-xYxMo2O9 (x = 0.05, x = 0.075) were investigated by means of broadband impedance spectroscopy. It was found that the compound with x = 0.05 is characterized not only by a typical jump of ionic conductivity at the temperature of α ↔ β phase transition (for LAMOX at around 800–830 K), but also by an anomalous fall in the range from 740 to 760 K. The analysis of impedance and XRD data showed that the later anomaly is related to the phase transition from metastable β′ to α phase. Formalism of the distribution of relaxation times (DRT) was used to examine these anomalies. In the vicinity of α ↔ β the DRT function consisted of two clearly separable peaks, indicating the coexistence of α and β phases. In specific cases of β′ → α and β → β′ transitions, only one DRT peak, which broadens at the temperatures of transition, was observed.

Characterization and optimization of highly active and Ba-deficient BaCo0.4Fe0.4Zr0.1Y0.1O3--based cathode materials for protonic ceramics fuel cells

Highly active triple-conducting (proton-, oxygen-ion-, and electron-conducting) perovskite oxide BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3- δ need to further optimize the electrochemical performance and chemical stability in carbon dioxide and water containing atmospheres, greatly limiting its widespread use in protonic ceramics fuel cells (PCFCs). Here, Ba-site deficient Ba 0.9 Co 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3- δ (B9CFZY) was synthesized and investigated as a promising candidate concerning the chemical and structural stability, electrical conductivity and electrochemical performance. Anode-supported button cells with the prevalent BaZr 0.1 Ce 0.7 Y 0.2 O 3- δ (BZCY) as electrolyte using B9CFZY and B9CFZY-BZCY cathodes, respectively, were fabricated and then measured at 700-550 °C. The maximum power density of the cells with B9CFZY-based cathodes increase from 452 mW cm −2 to 537 mW cm −2 at 700 °C, however, the corresponding polarization loss decreases from 0.30 to 0.15 Ω cm 2 by adding proton-conducting BZCY. Importantly, to better explore the reasons for the improved electrochemical performance, the distribution function of relaxation time (DRT) is used to distinguish different electrode polarization processes of both cells. The results indicate the polarization peaks (P3) of cells with composite cathode resulting from oxygen gas adsorption and dissociation can be greatly accelerated as well as the polarization peaks (P2) resulting from oxygen species diffusion to three phase boundaries or active sites in the cathode. The dramatic improvements demonstrate Ba deficient B9CFZY-BZCY material can be a very competitive cathode material for PCFCs.

Characterization of Sr2Fe1.5Mo0.5O6-δ -Gd0.1Ce0.9O1.95 symmetrical electrode for reversible solid oxide cells

Development of reversible solid oxide cells (RSOCs) must face one major challenge of the poor reliability origination from the oxidization of Ni-based hydrogen electrode materials. In this work, Sr2Fe1.5Mo0.5O6-δ -Gd0.1Ce0.9O1.95 (SFM-GDC) symmetrical electrode working both air and hydrogen electrode is designed and investigated for RSOCs. Regardless of the redox condition, SFM shows excellent structural stability by the XRD analysis and HR-TEM observation. Meanwhile, XPS analysis obviously demonstrates the co-existence of Fe2+/Fe3+ and Mo5+/Mo6+ couples, of which both proportions increase with the reduce oxygen partial pressure. Applying SFM-GDC symmetrical electrode, the 300 μm-thick YSZ electrolyte-supported RSOCs with GDC buffer layers show acceptance electrochemical performance, and switch smoothly between power generation and electrolysis modes with no obvious degradation after 20 h short-term stability working under humidified (∼3%H2O) H2 and 3%H2O-air atmospheres, respectively. Besides, the impedance spectrum were further studied using a relaxation time distribution function (DRT), and two polarization peaks (P1, P2) observed in the power generation mode shifted to the left at low frequency with the reduced temperature, while one more new polarization peak (P3) corresponds to the reaction gas diffusion owing to the low concentration steam (∼3% H2O) in electrolysis mode. This research highlights that the stable and efficient SFM-GDC symmetrical electrode can be the potential RSOCs electrode candidates.

A theory of distribution functions of relaxation times for the deconvolution of immittance data

Deconvolution of immittance spectroscopy (IS) data into a not directly measurable distribution of uncorrelated relaxation times (DRT) of polarisation processes occurring in the measured system provides useful information on the system. It primarily regards the identification of the number of such processes through their relaxation time constants, τ. Upon changing the conditions of the measurement, it also covers the variation particularly of the position and intensity of the relaxation time in the DRT spectrum.These information revealed by numerical inversion commonly using constrained least squares (LS) minimisation or fast Fourier transformation (FFT), help to construct an equivalent electrical circuit (EEC) model, which subsequently allows complex nonlinear least squares (CNLS) fitting of the IS data to simulate system behaviour.The inverse problem of deconvolving IS data into DRT is based on the principle of superposition of the immittances of passive (lumped) elements, such as a resistor, R, an inductor, L and a capacitor, C combined in parallel or series and forming branches of RLC electrical circuit networks of different types (Kelvin-Voigt, Maxwell-Wagner, Cauer, Foster, etc.). In the limit of an infinite number of branches, the network immittance convolved with the DRT function is mathematically described by a Fredholm singular integral equation (SIE) equated with the immittance of the studied system.As a novelty, from a SIE of the second kind, we derive the hitherto concealed complex valuedness of the DRT using the Hilbert integral transform (HT) and DRT properties for Kelvin-Voigt type RLC networks. We emphasise the necessity and usefulness of complex valued DRT for its numerical estimation by the FFT method and LS minimisation. We also provide for the derivation of theoretical DRT from rational immittances known analytically in closed form, e.g. assuming their representation by a HT compliant EEC model.

Impedance characterization of supported oxygen ion conducting electrolytes

Electrochemical impedance spectroscopy is a widely used tool to study electrochemical reactions in batteries, fuel cells and other electrochemical energy conversion devices. However, conduction processes in the electrolyte of high temperature fuel or electrolysis cells (SOFC/SOEC) are inaccessible during operation, severely restricting the information that can be obtained about performance and degradation of the electrolyte. Using the distribution function of relaxation times (DRT), we study the ionic conduction properties and degradation phenomena in multi-layered solid electrolytes, ex situ and at low temperatures. The investigation of full cells in air enables a detailed analysis of the conductivity of supported electrolytes as thin as 1 μm, as well as the relative contributions of multilayered electrolytes. Furthermore, three case studies are presented concerning the degradation mechanism in SOFC and SOEC operation, showcasing the ability of this technique to distinguish the effects of grain boundary contamination, formation of solid solutions and the formation of porosity on the ionic conductivity of thin, supported electrolytes.

Determination of grain boundary conductivity using distribution function of relaxation times (DFRT) analysis at room temperature in 10 mol% Gd doped ceria: A non-classical electrostrictor

The electrical conductivity of Ce0.90Gd0.10O1.95 oxide ion conductor is studied, emphasizing distribution function of relaxation times (DFRT) analysis of impedance spectroscopy measurements. The corresponding powder has been prepared by co-precipitation method and sintered at 1300 °C. The formation of the fluorite phase is confirmed by X-ray diffraction. The temperature dependence of ionic conductivity has been studied at different bias voltages. The impedance spectra are analysed by impedance spectroscopy genetic programming (ISGP) that finds an analytic form of the DFRT. Interestingly, both the grain and grain boundary conductivities can be identified at room temperature by analysing the DFRTs. At higher temperatures and higher bias voltages, the grain boundary diffusion process of oxygen ions is identified. Both the grain and grain boundary activation energies are bias independent.

Structure and electrical conductivity of Ta doped La2Mo2O9 oxide ion conductors

In this work, we have investigated the crystal structure, thermal, vibrational, microstructural, and electrical properties of Ta doped La2Mo2O9 oxide ion conductors. The Rietveld refinements on the X-ray diffraction patterns confirm the α phase similar to that of undoped La2Mo2O9 at room temperature. α → β phase transition is confirmed by the differential scanning calorimetry analysis. The microcrystalline samples have grain sizes ∼10 μm along with well-defined grain boundaries. The infrared and Raman spectra mainly consist of MoO4 bands. The electrical conductivity of the highly dense pellets was analyzed by the impedance spectroscopy genetic programming method coupled with distribution function of relaxation times (DFRTs). Each DFRT consists of three main peaks conferring bulk, ionic, and electronic contributions of the grain boundary. The higher oxide ion conductivity in the β phase is identified due to the electronic contribution of the grain boundary for the samples. The capacitance for bulk and ionic parts of the grain boundary are almost temperature independent, whereas the electronic contribution varies turbulently. The incorporation reaction suggests that the sample with 5 wt. % Ta has the maximum oxide ion conductivity, which is further verified by the resistances obtained from the DFRT analysis.

3D CFD Modelling of Low Temperature Pemfcs

Computational fluid dynamics (CFD) is becoming more and more an essential tool to gain deeper insight into the physics of proton exchange membrane fuel cells (PEMFCs). The goal is to achieve an optimized fuel cell design as a further step towards the commercialization of PEMFCs as an alternative to common automotive fuel engines. Nowadays a validated CFD model provides one means of improving the performance of fuel cells. The open-source code of Beale et al. [1] is a generic framework for simulating different types of fuel cells. The authors extended it to a full three-dimensional model using additional model equations and modified source terms. According to the integrated cell concept used in the open-source code three additional so-called 'child' meshes are introduced to account for charge transport and water transport in the polymer electrolyte membrane. The parameters of the Butler-Volmer equation (Figure 1, top), describing the electrochemical kinetics of the fuel cell, are used as fitting parameters in most existing literature. In this work the authors use a set of experimentally determined parameters in order to reduce the number of uncertain/fitting parameters.The method used to determine this set of parameters is electrochemical impedance spectroscopy whereby the data is analysed using the distribution function of relaxation times [2]. This method helps to separate the polarization processes contributing to the overall polarization loss in a clearer way. The numerical results of the model described above are compared to polarization curves measured by experiments. The results show good agreement (Figure 1, bottom) for two different humidifications (40% RH and 70% RH) in the activation and ohmic regions.

A general theory for the impedance response of dielectric films with a distribution of relaxation times

The analysis of the electrochemical impedance spectroscopy (EIS) response of electrodes and interfaces in terms of a distribution function of relaxation times (DFRT) has become an important topic of basic and applied research. For systems such as oxide films, passive layers, inhibitors, coatings and biological tissues, that distribution may arise as a consequence of normal-to-surface distributions of physical properties such as the electrical resistivity. The aim of this work is to relate the frequency response of those systems to the statistical properties of the distribution function, focusing on frequency dispersion behavior. The theory presented here is successfully applied to well-known models widely employed in the literature to interpret frequency dispersion in films (Young model, CPE behavior and ZARC response), but the analysis is also successful in predicting the response from arbitrary distributions such as the lognormal, Weibull and Cauchy distributions. The results apply mainly to the asymptotic frequency behavior. It is also shown that when the range of values of the distributed property is bounded, then there appear two critical frequencies at which a crossover from frequency dispersion towards ideal response takes place.

Sintering aid (ZnO) effect on proton transport in BaCe0.35Zr0.5Y0.15O3‐δ and electrode phenomena studied by distribution function of relaxation times

AbstractIn this work, we have employed an evolutionary programming technique to analyse the impedance spectroscopy (IS) of a ceramic proton conductor BaCe0.35Zr0.5Y0.15O3‐δ (BCZY) to study its proton transport properties as well as the electrode reactions kinetics at the Pt|BCZY interface. The distribution functions of relaxation times (DFRT) obtained from the impedance analysis were used to evaluate the physical parameters such as relaxation time constant, resistance, reactance/capacitance, conductivities, activation energies, grain‐boundary space charge potential Φ(0, T), and electrode polarization resistance. The effect of ZnO sintering aid (2 wt%) on charge‐transfer processes at bulk, grain boundaries and Pt|BCZY interface were thoroughly studied. Φ(0, T) is increased and grain‐boundary conductivity (σgb) is decreased by an order of magnitude due to the presence of Zn at the grain boundaries, whereas bulk properties appear to be unchanged. Variation in σgb with temperature is explained by correlating the grain‐boundary capacitance (Cgb), relaxation time (τgb), space charge effect, and the defect associations (eg, Y‐OH). The anodic functions, for example, hydrogen oxidation kinetics at the electrode (Pt) surface and Pt‐BCZY interface, are explained through the symmetrical cell study and the behavior of relaxation time constants (τ) with temperature.