On the use of the constant phase element to understand variation in grain boundary properties

McNealy, Benjamin E.; Hertz, Joshua L.

doi:10.1016/j.ssi.2013.12.030

Cited by 43 publications

(36 citation statements)

References 23 publications

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“…It provides the measure of the non-ideality of the device in tests with values between 0.7 and 1. 32 The capacitance values calculated using the fitting parameters are in the range of 10 -10 to 10 -8 F. Therefore, the semicircles observed by low-frequency impedance spectroscopy can be unambiguously assigned to the grain boundary resistance Rgb (Figure 4a). 29,33 The second R-CPE circuit is associated with the electrode contribution.…”

Section: Ionic Conductivitymentioning

confidence: 86%

Impact of sintering temperature on phase formation, microstructure, crystallinity and ionic conductivity of Li1.5Al0.5Ti1.5(PO4)3

Davaasuren

Tietz

2019

Solid State Ionics

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A systematic study was carried out to explore the impact of sintering temperature on the densification, phase formation, microstructure, crystallinity, and ionic conductivity of Li1.5Al0.5Ti1.5(PO4)3 (LATP). There is clear evidence that a) both the total conductivity and bulk conductivity increase with increasing sintering temperature, and b) the phase purity, crystallinity and compositional homogeneity range of LATP are the key factors that influence the bulk ionic conductivity. Furthermore, the influence of a sintering aid (Li2B4O7) on the microstructure and ionic conductivity of LATP was probed. The Li2B4O7 improved the microstructural parameters of the LATP electrolyte and thus remarkably reduced the grain boundary resistance of the pristine LATP from 1000 Ω to 550 Ω. The sintering aid Li2B4O7 did not influence the stoichiometry or the long-range order of LATP but rather acted as an ion-conducting bridge between the LATP grains facilitating the Li-ion transport.

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Section: Ionic Conductivitymentioning

confidence: 86%

Impact of sintering temperature on phase formation, microstructure, crystallinity and ionic conductivity of Li1.5Al0.5Ti1.5(PO4)3

Davaasuren

Tietz

2019

Solid State Ionics

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“…Constant-phase elements (CPE) are empirical circuit elements [330] which have been used to model a distribution of RC -elements in electrical circuits, for example, due to a distribution of trap states [331] or grain boundaries [332]. Using the known rules for how to calculate the overall Z of a circuit from its constituent elemental impedances, one can find an expression for Z which can be compared to recorded data [330].…”

Section: Impedance Spectroscopymentioning

confidence: 99%

Ti- and Fe-related charge transition levels in β−Ga2O3

Zimmermann

Frodason

Barnard

et al. 2020

Applied Physics Letters

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This thesis would not have been possible without the support of many people, and I am eternally grateful for all the support. I hope to see some of you again in the future! The main objective of my PhD project was to study defects in semiconducting oxides within the research project FOXHOUND headed by Prof. Lasse Vines, my main supervisor. I am grateful to Lasse for the opportunity to work on this topic. I have learned much more than I imagined I would when I started. Lasse, you have been a patient and competent supervisor who always took time to answer endless streams of questions. Prof. Truls Norby and Assoc. Prof. Anette Eleonora Gunnaes were co-advisors for my PhD project. I am grateful to Truls for introducing me to the chemist's view on defects and his group FASE/ELCHEM. I am truly sad that I did not get to collaborate more with Anette. I also want to thank Prof. Eduard Monakhov and the late Prof. Bengt Gunnar Svensson. Both were valuable unofficial advisers on my PhD, and helped moving my work along. Most of my work was carried out within the semiconductor physics group at the University of Oslo (LENS), and I would like to thank of all its current and former members for contributing to my work in many ways. There are some people who deserve special thanks. First of all, I am grateful to my long-term office mates Torunn, Sigbjørn and Josef for sharing many conversations and being there for each other. Secondly, I am particularly grateful to all my close collaborators at LENS, and especially Julie, Philip, Ymir, Vegard R., Vegard O., Viktor and Espen. I also want to thank our engineers (Micke, Halvor, Christoph and Viktor) and administrative staff (Marit, Heine and Kristin) for keeping things running! Also, thanks to Ilia, Robert, Vegard R. and Jon for taking care of the needs of the E-Lab and the Online-Setup. I was a co-supervisor for two master students: Vegard R. and Espen. I hope both of them learned something from me, because I did definitely learn from them. I am particularly grateful to Vegard R. for being a large part in building the steady-state photo-capacitance setup used in this work. I also would like to thank all my co-authors from outside of Oslo: Frank from Dresden, Willem, Walter and Danie from Pretoria, Klaus and Zbigniew from Berlin, Antti from Aalto and Joel from California. Special thanks to Willem, Walter and Danie for hosting me in Pretoria and showing me around. Last but not least, I would like to thank my family and my friends for their support!

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“…In these equivalent circuits, the constant phase elements (CPE1, CPE2) were selected based on SEM (Figure 3) and textural analysis (Figure 4). CPE describes a nonideal capacitive process, [12,44] which, for the purposes of this study, was used to model the porous structure of the material and its heterogeneous surface (Figure 4a–d) [45,46]. The numerical results of the equivalent circuits are summarized in Appendix A (Table A2 and Table A3).…”

Section: Resultsmentioning

confidence: 99%

Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions

2019

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The focus of this paper is centered on the thermal reduction of KMnO4 at controlled temperatures of 400 and 800 °C. The materials under study were characterized by atomic absorption spectroscopy, thermogravimetric analysis, average oxidation state of manganese, nitrogen adsorption–desorption, and impedance spectroscopy. The structural formulas, found as a result of these analyses, were K 0.29 + ( M n 0.84 4 + M n 0.16 3 + ) O 2.07 · 0.61 H 2 O and K 0.48 + ( M n 0.64 4 + M n 0.36 3 + ) O 2.06 · 0.50 H 2 O . The N2 adsorption–desorption isotherms show the microporous and mesoporous nature of the structure. Structural analysis showed that synthesis temperature affects the crystal size and symmetry, varying their electrical properties. Impedance spectroscopy (IS) was used to measure the electrical properties of these materials. The measurements attained, as a result of IS, show that these materials have both electronic and ionic conductivity. The conductivity values obtained at 10 Hz were 4.1250 × 10−6 and 1.6870 × 10−4 Ω−1cm−1 for Mn4 at 298 and 423 K respectively. For Mn8, the conductivity values at this frequency were 3.7074 × 10−7 (298) and 3.9866 × 10−5 Ω−1cm−1 (423 K). The electrical behavior was associated with electron hopping at high frequencies, and protonic conduction and ionic movement of the K+ species, in the interlayer region at low frequencies.

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On the use of the constant phase element to understand variation in grain boundary properties

Cited by 43 publications

References 23 publications

Impact of sintering temperature on phase formation, microstructure, crystallinity and ionic conductivity of Li1.5Al0.5Ti1.5(PO4)3

Impact of sintering temperature on phase formation, microstructure, crystallinity and ionic conductivity of Li1.5Al0.5Ti1.5(PO4)3

Ti- and Fe-related charge transition levels in β−Ga2O3

Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions

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