1
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Kemp D, De Souza RA. One Stone, Two Birds: Using High Electric Fields to Enhance the Mobility and the Concentration of Point Defects in Ion-Conducting Solids. J Am Chem Soc 2024; 146:4783-4794. [PMID: 38344804 PMCID: PMC10885144 DOI: 10.1021/jacs.3c12843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Improving the ionic conductivity of outstanding, composition-optimized crystalline electrolytes is a major challenge. Achieving increases of orders of magnitude requires, conceivably, highly nonlinear effects. One known possibility is the use of high electric fields to increase point-defect mobility. In this study, we investigate quantitatively a second possibility that high electric fields can increase substantially point-defect concentrations. As a model system, we take a pyrochlore oxide (La2Zr2O7) for its combination of structural vacancies and dominant anti-Frenkel disorder; we perform molecular-dynamics simulations with many-body potentials as a function of temperature and applied electric field. Results within the linear regime yield the activation enthalpies and entropies of oxygen-vacancy and oxygen-interstitial migration, and from three independent methods, the enthalpy and entropy of anti-Frenkel disorder. Transport data for the nonlinear regime are consistent with field-enhanced defect concentrations and defect mobilities. A route for separating the two effects is shown, and an analytical expression for the quantitative prediction of the field-dependent anti-Frenkel equilibrium constant is derived. In summary, we demonstrate that the one stone of a nonlinear driving force can be used to hit two birds of defect behavior.
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Affiliation(s)
- Dennis Kemp
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Roger A De Souza
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
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2
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Develos-Bagarinao K, Yamaguchi T, Kishimoto H. Elucidating the performance benefits enabled by YSZ/Ni-YSZ bilayer thin films in a porous anode-supported cell architecture. NANOSCALE 2023. [PMID: 37376979 DOI: 10.1039/d3nr01604h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Increasing the performance and improving the stability of solid oxide cells are critical requirements for advancing this technology toward commercial applications. In this study, a systematic comparison of anode-supported cells utilizing thin films with those utilizing conventional screen-printed yttria-stabilized zirconia (YSZ) is performed. High-resolution secondary ion mass spectrometry (SIMS) imaging is used to visualize, for the first time, the extent of Ni diffusion into screen-printed microcrystalline YSZ electrolytes of approximately 2-3 μm thickness, due to the high temperature (typically >1300 °C) used in the conventional sintering process. As an alternative approach, dense YSZ thin films and Ni(O)-YSZ nanocomposite layers are prepared using pulsed laser deposition (PLD) at a relatively low temperature of 750 °C. YSZ thin films exhibit densely packed nanocrystalline grains and a remarkable suppression of Ni diffusion, which are further associated with some reduction in the ohmic resistance of the cell, especially in the low temperature regime. Moreover, the use of a Ni-YSZ nanocomposite layer resulted in improved contact at the YSZ/anode interface as well as a higher density of triple phase boundaries due to the nanoscale Ni and YSZ grains being homogeneously distributed throughout the structure. The cells utilizing the YSZ/Ni-YSZ bilayer thin films show excellent performance in fuel cell operation and good durability in short-term operation up to 65 hours. These results provide insights into ways to improve the electrochemical performance of SOCs by utilizing innovative thin film structures in conjunction with commercially viable porous anode-supported cells.
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Affiliation(s)
- Katherine Develos-Bagarinao
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba West, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
| | - Toshiaki Yamaguchi
- Energy Process Research Institute, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba West, 16-1 Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
| | - Haruo Kishimoto
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba West, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
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3
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Nakayama M, Nakano K, Harada M, Tanibata N, Takeda H, Noda Y, Kobayashi R, Karasuyama M, Takeuchi I, Kotobuki M. Na superionic conductor-type LiZr 2(PO 4) 3 as a promising solid electrolyte for use in all-solid-state Li metal batteries. Chem Commun (Camb) 2022; 58:9328-9340. [PMID: 35950409 DOI: 10.1039/d2cc01526a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
All-solid-state Li-ion batteries are of considerable interest as safer alternatives to Li-ion batteries containing flammable organic electrolytes. To date, however, achieving sufficient charging and discharging rates, in addition to capacity, at room temperature using these all-solid-state batteries has been challenging. To overcome these issues, material simulations and informatics investigations of a relatively new Na superionic conductor (NASICON)-type LiZr2(PO4)3 (LZP) electrolyte were conducted to elucidate its characteristics and material functions. The following thermodynamic and/or kinetic properties of NASICON-type Li-ion conductive oxides were investigated with respect to the crystal structure mainly using material simulation and informatics approaches: (1) the electrochemical stabilities of LZP materials with respect to Li metal and (2) Li-ion conductivities in the bulk and at the grain boundaries. An efficient materials informatics search method was employed to optimise the material functions of the LZP electrolyte via Bayesian optimisation. This study should promote the application of LZP in all-solid-state batteries for use in technologies such as mobile devices and electric vehicles and enable more complex composition and process control.
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Affiliation(s)
- Masanobu Nakayama
- Department of Advanced Ceramics, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan. .,Frontier Research Institute for Materials Science (FRIMS), Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan.,Unit of Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Katsura, Saikyo-ku, Kyoto, 615-8520, Japan
| | - Koki Nakano
- Department of Advanced Ceramics, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan. .,Frontier Research Institute for Materials Science (FRIMS), Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan
| | - Maho Harada
- Department of Advanced Ceramics, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan.
| | - Naoto Tanibata
- Department of Advanced Ceramics, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan. .,Unit of Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Katsura, Saikyo-ku, Kyoto, 615-8520, Japan
| | - Hayami Takeda
- Department of Advanced Ceramics, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan. .,Unit of Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Katsura, Saikyo-ku, Kyoto, 615-8520, Japan
| | - Yusuke Noda
- Department of Information and Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama, 719-1197, Japan
| | - Ryo Kobayashi
- Department of Applied Physics, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan
| | - Masayuki Karasuyama
- Department of Computer Science, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan
| | - Ichiro Takeuchi
- Department of Computer Science, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi, 466-8555, Japan.,RIKEN Center for Advanced Intelligence Project, 1-4-1 Nihonbashi, Chuo-ku, Tokyo, 103-0027, Japan.,Faculty of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Masashi Kotobuki
- Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gungjuan Rd., Taishan Dist., New Taipei City, 24301, Taiwan
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4
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Guan SH, Liu ZP. Theoretical aspects on doped-zirconia for solid oxide fuel cells: From structure to conductivity. CHINESE J CHEM PHYS 2021. [DOI: 10.1063/1674-0068/cjcp2103044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Shu-hui Guan
- Shanghai Academy of Agricultural Sciences, Shanghai 201403, China
- Collaborative Innovation Center of Chemistry for Energy Material, Shanghai Key Laboratory of molecular Catalysis and Innovative Materials, Key Laboratory of Computational Physical Science, Department of Chemistry, Fudan University, Shanghai 200438, China
| | - Zhi-pan Liu
- Collaborative Innovation Center of Chemistry for Energy Material, Shanghai Key Laboratory of molecular Catalysis and Innovative Materials, Key Laboratory of Computational Physical Science, Department of Chemistry, Fudan University, Shanghai 200438, China
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5
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Waldow SP, Statham BJ, Wardenga HF, Weirich TE, Klein A, De Souza RA. Oxygen Surface Exchange and Tracer Diffusion in Differently Oriented Thin Films of Gd-Doped CeO 2. ACS APPLIED MATERIALS & INTERFACES 2020; 12:36768-36777. [PMID: 32668162 DOI: 10.1021/acsami.0c09605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The exchange of 18O between gaseous molecular oxygen and thin-film samples of Ce0.99Gd0.01O1.995 with two different, nominal surface orientations [(111) and (110)] was studied. Oxygen isotope exchange experiments were conducted in the temperature range of 573 ≤ T/K ≤ 673 at an oxygen activity of aO2 = 0.2. Subsequently, secondary ion mass spectrometry (SIMS) measurements were performed on the thin-film samples to obtain 18O isotope depth profiles. All 18O diffusion profiles showed two features, suggesting spatially nonuniform oxygen tracer diffusion coefficients in the samples. A numerical solution to the diffusion equation was used to describe the experimental profiles and yielded oxygen tracer diffusion coefficients D* and oxygen surface exchange coefficients k*. Values of D* obtained were found, surprisingly, to be different for the two orientations and also orders of magnitude lower than values for ceramic samples in this temperature range. As possible explanations, we examine quantitatively the effect of halide anion impurities and the effect of ultrasmall columnar grains on oxygen tracer diffusion. Surface exchange coefficients for the (111) oriented surface were found to be roughly 1 order of magnitude higher than those for (110). We discuss two possible explanations for the observed behavior: the enrichment of anion impurities at the surface and the interaction between the surface and vapor water in the gas phase.
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Affiliation(s)
- Stephan P Waldow
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Benjamin J Statham
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Hans F Wardenga
- Department of Materials and Earth Sciences, Electronic Structure of Materials, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Thomas E Weirich
- Institute of Crystallography, RWTH Aachen University, 52056 Aachen, Germany
| | - Andreas Klein
- Department of Materials and Earth Sciences, Electronic Structure of Materials, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Roger A De Souza
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
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6
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PEKKAN G, PEKKAN K, BAYINDIR BÇ, ÖZCAN M, KARASU B. Factors affecting the translucency of monolithic zirconia ceramics: A review from materials science perspective. Dent Mater J 2020; 39:1-8. [DOI: 10.4012/dmj.2019-098] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Gürel PEKKAN
- Department of Prosthodontics, Faculty of Dentistry, Tekirdag Namik Kemal University
| | - Keriman PEKKAN
- Department of Ceramics and Glass, Faculty of Fine Arts, Kutahya Dumlupinar University
| | | | - Mutlu ÖZCAN
- Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Center for Dental and Oral Medicine, Dental Materials Unit, University of Zürich
| | - Bekir KARASU
- Department of Metallurgical and Materials Engineering, Faculty of Engineering, Eskisehir Technical University
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7
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Schwab C, Höweling A, Windmüller A, Gonzalez-Julian J, Möller S, Binder JR, Uhlenbruck S, Guillon O, Martin M. Bulk and grain boundary Li-diffusion in dense LiMn 2O 4 pellets by means of isotope exchange and ToF-SIMS analysis. Phys Chem Chem Phys 2019; 21:26066-26076. [PMID: 31746869 DOI: 10.1039/c9cp05128g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lithium diffusion in LiMn2O4 pellets is studied by means of isotope exchange and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). A 6Li-enriched film deposited by Pulsed Laser Deposition (PLD) on a dense LiMn2O4 pellet with natural abundance of lithium isotopes is used to study the tracer diffusion of lithium. The measured profiles are analyzed by numerical models describing the 6Li tracer diffusion from the film into the pellet. Experiments in the Harrison type B regime of diffusion kinetics allow for the distinction and simultaneous determination of bulk and grain boundary diffusion coefficients. Changing the experimental conditions to reach Harrison type A behavior yields effective diffusion coefficients for lithium tracer diffusion in LiMn2O4. Activation energies for bulk and grain boundary diffusion were obtained from experiments at different temperatures. Our values are critically compared to previous studies.
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Affiliation(s)
- C Schwab
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany.
| | - A Höweling
- Institute for Applied Materials (IAM), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - A Windmüller
- Institute of Energy and Climate Research (IEK-1), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - J Gonzalez-Julian
- Institute of Energy and Climate Research (IEK-1), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - S Möller
- Institute of Energy and Climate Research (IEK-1), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - J R Binder
- Institute for Applied Materials (IAM), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - S Uhlenbruck
- Institute of Energy and Climate Research (IEK-1), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - O Guillon
- Institute of Energy and Climate Research (IEK-1), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - M Martin
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany. and Helmholtz-Institute Münster (IEK-12), Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149 Münster, Germany
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8
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Symington AR, Molinari M, Brincat NA, Williams NR, Parker SC. Defect segregation facilitates oxygen transport at fluorite UO 2 grain boundaries. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20190026. [PMID: 31280720 PMCID: PMC6635626 DOI: 10.1098/rsta.2019.0026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
An important challenge for modelling transport in materials for energy applications is that in most applications they are polycrystalline, and hence it is critical to understand the properties in the presence of grain boundaries. Moreover, most grain boundaries are not pristine stoichiometric interfaces and hence dopants are likely to play a significant role. In this paper, we describe our recent work on using atomistic molecular dynamics simulations to model the effect of doped grain boundaries on oxygen transport of fluorite structured UO2. UO2, much like other fluorite grain boundaries, are found to be sinks for oxygen vacancy segregation relative to the grain interior, thus facilitating oxygen transport. Fission products further enhance diffusivity via strong interactions between the impurities and oxygen defects. Doping produces a striking structural alteration in the Σ5 class of grain boundaries that enhances oxygen diffusivity even further. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.
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Affiliation(s)
- A. R. Symington
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - M. Molinari
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK
| | - N. A. Brincat
- AWE plc, Aldermaston, Reading, Berkshire RG7 4PR, UK
| | | | - S. C. Parker
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
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9
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De Souza RA, Dickey EC. The effect of space-charge formation on the grain-boundary energy of an ionic solid. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20180430. [PMID: 31280710 PMCID: PMC6635631 DOI: 10.1098/rsta.2018.0430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
Taking the model system of an oxide containing acceptor dopant cations and charge-compensating oxygen vacancies, we calculate at the continuum level the change in the excess grain-boundary energy of an ionic solid upon space-charge formation. Two different cases are considered for the space-charge layers: (i) only vacancies attain electrochemical equilibrium and (ii) both dopants and vacancies attain electrochemical equilibrium. The changes calculated for a specific set of grain boundaries indicate that, depending on dopant concentration, space-charge formation can decrease the excess free energy by up to 15% in the first case and by up to 45% in the second case. The possibility of the excess grain-boundary energy going to zero and the possible effects of an external electric field on the excess grain-boundary energy are also discussed. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.
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Affiliation(s)
- R. A. De Souza
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - E. C. Dickey
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907, USA
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10
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Shen Z, Skinner SJ, Kilner JA. Oxygen transport and surface exchange mechanisms in LSCrF-ScCeSZ dual-phase ceramics. Phys Chem Chem Phys 2019; 21:13194-13206. [PMID: 31173017 DOI: 10.1039/c9cp02175b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For the mechanisms by which the oxygen gets incorporated in a dual-phase composite system, three hypotheses, i.e. cation inter-diffusion, spillover type and self-cleaning of the perovskite-structured phase, have been provided in the literature. However, experimentally a consensus on the most likely mechanism is yet to be reached. In this work, a specially fused sample of the lanthanum strontium chromium ferrite (LSCrF)-scandia/ceria-stabilised zirconia (ScCeSZ) dual-phase material was investigated. Among the three potential mechanisms, no obvious cation inter-diffusion was firstly observed. A cleaner surface of the ScCeSZ phase was confirmed in the fused sample than in the isolated ScCeSZ single-phase sample while impurity layers were clearly observed on the LSCrF surface, suggesting the cleaning effect from the perovskite. However, more evidence implies that the cleaning effect is not the only reason for the synergistic effects between these two phases. Observations via SIMS analysis lend strong support to the 'spillover-type' mechanism as the oxygen isotopic fraction on the surface of the ScCeSZ increased compared to the isolated single-phase and as the distance to the heterojunction increases, the oxygen isotopic fraction decreases. Moreover, oxygen depleted layers were clearly seen on the top layers of the LSCrF surface which may be associated with the higher oxygen diffusivity in the surface/sub-surface layers, oxygen grain boundary fast diffusion and the impurities on the perovskite phase. For this sample, a combination of 'spillover' and 'self-cleaning' type mechanisms is suggested to be the potential possibility while the contribution from the cation inter-diffusion for this specific sample is proven to be low.
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Affiliation(s)
- Zonghao Shen
- Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
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11
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Ivanov-Schitz AK, Mazo GN. Atomistic Simulation of Interfaces in Materials of Solid State Ionics. CRYSTALLOGR REP+ 2018. [DOI: 10.1134/s106377451801008x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Galin MZ, Ivanov-Schitz AK, Mazo GN. Molecular Dynamics Simulation of the Structure and Ion Transport in the Ce1 – xGd x O2 – δ|YSZ Heterosystem. CRYSTALLOGR REP+ 2018. [DOI: 10.1134/s1063774518010078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Gries UN, Schraknepper H, Skaja K, Gunkel F, Hoffmann-Eifert S, Waser R, De Souza RA. A SIMS study of cation and anion diffusion in tantalum oxide. Phys Chem Chem Phys 2018; 20:989-996. [DOI: 10.1039/c7cp07441g] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diffusion experiments reveal that anions are more mobile than cations in L-Ta2O5; together with literature data, they suggest that oxygen interstitials are the defects responsible for anion diffusion.
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Affiliation(s)
- U. N. Gries
- Institute of Physical Chemistry and JARA-FIT, RWTH Aachen University
- 52056 Aachen
- Germany
| | - H. Schraknepper
- Institute of Physical Chemistry and JARA-FIT, RWTH Aachen University
- 52056 Aachen
- Germany
| | - K. Skaja
- Peter Grünberg Institute (PGI-7), Forschungszentrum Jülich GmbH
- Germany
| | - F. Gunkel
- Peter Grünberg Institute (PGI-7), Forschungszentrum Jülich GmbH
- Germany
| | | | - R. Waser
- Peter Grünberg Institute (PGI-7), Forschungszentrum Jülich GmbH
- Germany
- Institute of Electronic Materials (IWE2), RWTH Aachen University
- Germany
| | - R. A. De Souza
- Institute of Physical Chemistry and JARA-FIT, RWTH Aachen University
- 52056 Aachen
- Germany
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14
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Li C, Pramana SS, Ni N, Kilner J, Skinner SJ. Surface Chemistry of La 0.99Sr 0.01NbO 4-d and Its Implication for Proton Conduction. ACS APPLIED MATERIALS & INTERFACES 2017; 9:29633-29642. [PMID: 28820933 DOI: 10.1021/acsami.7b04856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Acceptor-doped LaNbO4 is a promising electrolyte material for proton-conducting fuel cell (PCFC) applications. As charge transfer processes govern device performance, the outermost surface of acceptor-doped LaNbO4 will play an important role in determining the overall cell performance. However, the surface composition is poorly characterized, and the understanding of its impact on the proton exchange process is rudimentary. In this work, the surface chemistry of 1 atom % Sr-doped LaNbO4 (La0.99Sr0.01NbO4-d, denoted as LSNO) proton conductor is characterized using LEIS and SIMS. The implication of a surface layer on proton transport is studied using the isotopic exchange technique. It has shown that a Sr-enriched but La-deficient surface layer of about 6-7 nm thick forms after annealing the sample under static air at 1000 °C for 10 h. The onset of segregation is found to be between 600 and 800 °C, and an equilibrium surface layer forms after 10 h annealing. A phase separation mechanism, due to the low solubility of Sr in LaNbO4, has been proposed to explain the observed segregation behavior. The surface layer was concluded to impede the water incorporation process, leading to a reduced isotopic fraction after the D216O wet exchange process, highlighting the impact of surface chemistry on the proton exchange process.
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Affiliation(s)
- Cheng Li
- Department of Materials, Imperial College London , Prince Consort Road, London SW7 2BP, United Kingdom
| | - Stevin S Pramana
- Department of Materials, Imperial College London , Prince Consort Road, London SW7 2BP, United Kingdom
| | - Na Ni
- Department of Materials, Imperial College London , Prince Consort Road, London SW7 2BP, United Kingdom
| | - John Kilner
- Department of Materials, Imperial College London , Prince Consort Road, London SW7 2BP, United Kingdom
| | - Stephen J Skinner
- Department of Materials, Imperial College London , Prince Consort Road, London SW7 2BP, United Kingdom
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15
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Perriot R, Dholabhai PP, Uberuaga BP. Disorder-induced transition from grain boundary to bulk dominated ionic diffusion in pyrochlores. NANOSCALE 2017; 9:6826-6836. [PMID: 28497819 DOI: 10.1039/c7nr01373f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We use molecular dynamics simulations to investigate the role of grain boundaries (GBs) on ionic diffusion in pyrochlores, as a function of the GB type, chemistry of the compound, and level of cation disorder. We observe that the presence of GBs promotes oxygen transport in ordered and low-disordered systems, as the GBs are found to have a higher concentration of mobile carriers with higher mobilities than in the bulk. Thus, in ordered samples, the ionic diffusion is 2D, localized along the grain boundary. When cation disorder is introduced, bulk carriers begin to contribute to the overall diffusion, while the GB contribution is only slightly enhanced. In highly disordered samples, the diffusive behavior at the GBs is bulk-like, and the two contributions (bulk vs. GB) can no longer be distinguished. There is thus a transition from 2D/GB dominated oxygen diffusivity to 3D/bulk dominated diffusivity versus disorder in pyrochlores. These results provide new insights into the possibility of using internal interfaces to enhance ionic conductivity in nanostructured complex oxides.
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Affiliation(s)
- Romain Perriot
- Materials Science and Technology Division, Los Alamos National Laboratory P.O. Box 1663, Los Alamos, NM 87545, USA.
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16
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Martin J, Gräf M, Kramer T, Jooss C, Choe MJ, Thornton K, Weitzel KM. Charge attachment induced transport - bulk and grain boundary diffusion of potassium in PrMnO 3. Phys Chem Chem Phys 2017; 19:9762-9769. [PMID: 28265624 DOI: 10.1039/c7cp00198c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The transport of potassium through praseodymium-manganese oxide (PrMnO3; PMO) has been investigated by means of the charge attachment induced transport (CAIT) technique. To this end, potassium ions have been attached to the front side of a 250 nm thick sample of PMO. The majority of the potassium ions become neutralized at the surface of the PMO, while some of the potassium ions diffuse through. Ex situ analysis of the sample by time-of-flight secondary ion mass spectrometry (ToF-SIMS) reveals pronounced concentration profiles of the potassium, which is indicative of diffusion. Two diffusion coefficients have been obtained, namely, the bulk diffusion coefficient and the diffusion coefficient associated with the grain boundaries. The latter conclusion is supported by transmission electron microscopy of thin lamella cut out from the sample, which reveals twin grain boundaries reaching throughout the entire sample as well as model calculations.
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Affiliation(s)
- Johannes Martin
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany.
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17
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Paving the way to nanoionics: atomic origin of barriers for ionic transport through interfaces. Sci Rep 2015; 5:17229. [PMID: 26673351 PMCID: PMC4682188 DOI: 10.1038/srep17229] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 10/27/2015] [Indexed: 12/03/2022] Open
Abstract
The blocking of ion transport at interfaces strongly limits the performance of electrochemical nanodevices for energy applications. The barrier is believed to arise from space-charge regions generated by mobile ions by analogy to semiconductor junctions. Here we show that something different is at play by studying ion transport in a bicrystal of yttria (9% mol) stabilized zirconia (YSZ), an emblematic oxide ion conductor. Aberration-corrected scanning transmission electron microscopy (STEM) provides structure and composition at atomic resolution, with the sensitivity to directly reveal the oxygen ion profile. We find that Y segregates to the grain boundary at Zr sites, together with a depletion of oxygen that is confined to a small length scale of around 0.5 nm. Contrary to the main thesis of the space-charge model, there exists no evidence of a long-range O vacancy depletion layer. Combining ion transport measurements across a single grain boundary by nanoscale electrochemical strain microscopy (ESM), broadband dielectric spectroscopy measurements, and density functional calculations, we show that grain-boundary-induced electronic states act as acceptors, resulting in a negatively charged core. Besides the possible effect of the modified chemical bonding, this negative charge gives rise to an additional barrier for ion transport at the grain boundary.
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18
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Baeumer C, Schmitz C, Ramadan AHH, Du H, Skaja K, Feyer V, Müller P, Arndt B, Jia CL, Mayer J, De Souza RA, Michael Schneider C, Waser R, Dittmann R. Spectromicroscopic insights for rational design of redox-based memristive devices. Nat Commun 2015; 6:8610. [PMID: 26477940 PMCID: PMC4634325 DOI: 10.1038/ncomms9610] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/10/2015] [Indexed: 11/23/2022] Open
Abstract
The demand for highly scalable, low-power devices for data storage and logic operations is strongly stimulating research into resistive switching as a novel concept for future non-volatile memory devices. To meet technological requirements, it is imperative to have a set of material design rules based on fundamental material physics, but deriving such rules is proving challenging. Here, we elucidate both switching mechanism and failure mechanism in the valence-change model material SrTiO3, and on this basis we derive a design rule for failure-resistant devices. Spectromicroscopy reveals that the resistance change during device operation and failure is indeed caused by nanoscale oxygen migration resulting in localized valence changes between Ti(4+) and Ti(3+). While fast reoxidation typically results in retention failure in SrTiO3, local phase separation within the switching filament stabilizes the retention. Mimicking this phase separation by intentionally introducing retention-stabilization layers with slow oxygen transport improves retention times considerably.
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Affiliation(s)
- Christoph Baeumer
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Christoph Schmitz
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Amr H. H. Ramadan
- Institute of Physical Chemistry, RWTH Aachen University and JARA-FIT, 52056 Aachen, Germany
| | - Hongchu Du
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
- Ernst Ruska-Centre, Forschungszentrum Juelich GmbH and RWTH Aachen University, 52425 Juelich, Germany
| | - Katharina Skaja
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Vitaliy Feyer
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Philipp Müller
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Benedikt Arndt
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Chun-Lin Jia
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
- Ernst Ruska-Centre, Forschungszentrum Juelich GmbH and RWTH Aachen University, 52425 Juelich, Germany
| | - Joachim Mayer
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
- Ernst Ruska-Centre, Forschungszentrum Juelich GmbH and RWTH Aachen University, 52425 Juelich, Germany
| | - Roger A. De Souza
- Institute of Physical Chemistry, RWTH Aachen University and JARA-FIT, 52056 Aachen, Germany
| | - Claus Michael Schneider
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
| | - Rainer Waser
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
- Institute of Materials in Electrical Engineering and Information Technology II, RWTH Aachen University, 52056 Aachen, Germany
| | - Regina Dittmann
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT, 52425 Juelich, Germany
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19
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He W, Liu JJ, Chen CS, Ni M. Oxygen permeation modeling for Zr0.84Y0.16O1.92–La0.8Sr0.2Cr0.5Fe0.5O3− asymmetric membrane made by phase-inversion. J Memb Sci 2015. [DOI: 10.1016/j.memsci.2015.05.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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20
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Schraknepper H, Bäumer C, Dittmann R, De Souza RA. Complex behaviour of vacancy point-defects in SrRuO3 thin films. Phys Chem Chem Phys 2015; 17:1060-9. [DOI: 10.1039/c4cp03632h] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Metastable point-defect concentrations on both anion and cation sublattices give rise to complex time-dependent diffusion behaviour and compositional and morphological changes in thin-film SrRuO3.
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Affiliation(s)
- Henning Schraknepper
- Institute of Physical Chemistry
- RWTH Aachen University and JARA-FIT
- 52056 Aachen
- Germany
| | - Christoph Bäumer
- Peter Grünberg Institut
- Forschungszentrum Jülich GmbH and JARA-FIT
- 52425 Jülich
- Germany
| | - Regina Dittmann
- Peter Grünberg Institut
- Forschungszentrum Jülich GmbH and JARA-FIT
- 52425 Jülich
- Germany
| | - Roger A. De Souza
- Institute of Physical Chemistry
- RWTH Aachen University and JARA-FIT
- 52056 Aachen
- Germany
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21
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Yokoi T, Yoshiya M, Yasuda H. Nonrandom point defect configurations and driving force transitions for grain boundary segregation in trivalent cation doped ZrO₂. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14179-14188. [PMID: 25378196 DOI: 10.1021/la503338x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The energetically favorable spatial configuration of M(3+) ions and oxide-ion vacancies near a symmetrical grain boundary (GB) in cubic zirconia is determined for various trivalent species M(3+) (M = Al, Sc, Y, Gd, La), and the driving force for grain boundary segregation (GBS) quantitatively examined using atomistic Monte Carlo simulations in conjunction with static lattice calculations. For a high concentration of ∼10 mol %, it is found that point defects near a GB plane preferentially occupy specific sites to minimize total lattice energy, rather than being randomly distributed. Systematic analysis shows that energetically stable configurations of segregants vary depending on their ionic radii. Analysis of the driving force for GBS as a function of dopant concentration reveals that three important factors govern GBS. First, occupation of specific sites by point defects is necessary to minimize the total lattice energy; enrichment of point defects near the GB plane with random configuration does not decrease the total lattice energy significantly because of strong Coulombic interactions. Second, the factors governing GBS change with increasing dopant concentration. At dilute concentrations, relief of bond strain is the dominant factor, while at high concentrations Coulombic interactions, which depend strongly on the specific arrangement of defects, become another dominant factor. Third, the stabilization of matrix cations, Zr(4+) ions, is the dominant factor to lower the driving force for GBS at all concentrations. In contrast, the stabilization of M(3+) ions does not necessarily contribute to GBS of point defects at high concentrations. These findings suggest practical ways to control GBS to enhance materials' properties or minimize detrimental effects.
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Affiliation(s)
- T Yokoi
- Department of Adaptive Machine Systems, Osaka University , 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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22
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Metlenko V, Ramadan AHH, Gunkel F, Du H, Schraknepper H, Hoffmann-Eifert S, Dittmann R, Waser R, De Souza RA. Do dislocations act as atomic autobahns for oxygen in the perovskite oxide SrTiO3? NANOSCALE 2014; 6:12864-76. [PMID: 25263456 DOI: 10.1039/c4nr04083j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The transport properties of edge dislocations comprising a symmetrical 6° [001] tilt grain boundary in weakly acceptor-doped SrTiO3 were investigated by means of various experimental and computational techniques. Oxygen transport along the dislocation array was probed by means of (18)O/(16)O exchange experiments under (standard) oxidising conditions (pO2 = 5 × 10(-1) bar) and also under reducing conditions (pO2 = 7 × 10(-22) bar) at T = 973 K. In both cases, isotope profiles obtained by Secondary Ion Mass Spectrometry (SIMS) indicated no evidence of fast diffusion along the dislocation array. Charge transport across the dislocation array was probed in equilibrium electrical conductivity measurements as a function of oxygen partial pressure, 10(-23) ≤ pO2/bar ≤ 1 at temperatures of T/K = 950, 1050, 1100. A significant decrease in the conductivity of the bicrystal (relative to that of a single crystal) was observed under oxidising conditions, but not under reducing conditions. These studies were complemented by static lattice simulations employing empirical pair-potentials. The simulations predict, that the tilt boundary comprises two types of dislocation cores, that the formation of oxygen vacancies is energetically preferred at both cores relative to the bulk, and that the migration of oxygen ions along both cores is hindered relative to the bulk. Combining all results and literature reports, we present a comprehensive and consistent picture of the transport properties of dislocations in SrTiO3.
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Affiliation(s)
- Veronika Metlenko
- Institute of Physical Chemistry, RWTH Aachen University and JARA-FIT, 52056 Aachen, Germany.
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23
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Kim SK, Khodorov S, Lubomirsky I, Kim S. A linear diffusion model for ion current across blocking grain boundaries in oxygen-ion and proton conductors. Phys Chem Chem Phys 2014; 16:14961-8. [DOI: 10.1039/c4cp01254b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We demonstrate the applicability of the linear diffusion model recently proposed for the current–voltage characteristics of grain boundaries in solid electrolytes.
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Affiliation(s)
- Seong K. Kim
- Department of Chemical Engineering and Materials Science
- University of California
- Davis, USA
| | - Sergey Khodorov
- Department of Materials Science
- Weizmann Institute of Science
- Rehovot, Israel
| | - Igor Lubomirsky
- Department of Materials Science
- Weizmann Institute of Science
- Rehovot, Israel
| | - Sangtae Kim
- Department of Chemical Engineering and Materials Science
- University of California
- Davis, USA
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24
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Funke K. Solid State Ionics: from Michael Faraday to green energy-the European dimension. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2013; 14:043502. [PMID: 27877585 PMCID: PMC5090311 DOI: 10.1088/1468-6996/14/4/043502] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/30/2013] [Indexed: 05/30/2023]
Abstract
Solid State Ionics has its roots essentially in Europe. First foundations were laid by Michael Faraday who discovered the solid electrolytes Ag2S and PbF2 and coined terms such as cation and anion, electrode and electrolyte. In the 19th and early 20th centuries, the main lines of development toward Solid State Ionics, pursued in Europe, concerned the linear laws of transport, structural analysis, disorder and entropy and the electrochemical storage and conversion of energy. Fundamental contributions were then made by Walther Nernst, who derived the Nernst equation and detected ionic conduction in heterovalently doped zirconia, which he utilized in his Nernst lamp. Another big step forward was the discovery of the extraordinary properties of alpha silver iodide in 1914. In the late 1920s and early 1930s, the concept of point defects was established by Yakov Il'ich Frenkel, Walter Schottky and Carl Wagner, including the development of point-defect thermodynamics by Schottky and Wagner. In terms of point defects, ionic (and electronic) transport in ionic crystals became easy to visualize. In an 'evolving scheme of materials science', point disorder precedes structural disorder, as displayed by the AgI-type solid electrolytes (and other ionic crystals), by ion-conducting glasses, polymer electrolytes and nano-composites. During the last few decades, much progress has been made in finding and investigating novel solid electrolytes and in using them for the preservation of our environment, in particular in advanced solid state battery systems, fuel cells and sensors. Since 1972, international conferences have been held in the field of Solid State Ionics, and the International Society for Solid State Ionics was founded at one of them, held at Garmisch-Partenkirchen, Germany, in 1987.
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Affiliation(s)
- Klaus Funke
- University of Münster, Institute of Physical Chemistry, Corrensstraße 30, D-48149 Münster, Germany
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25
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Aydin H, Korte C, Janek J. 18O-tracer diffusion along nanoscaled Sc 2O 3/yttria stabilized zirconia (YSZ) multilayers: on the influence of strain. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2013; 14:035007. [PMID: 27877580 PMCID: PMC5090511 DOI: 10.1088/1468-6996/14/3/035007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 05/09/2013] [Indexed: 06/06/2023]
Abstract
The oxygen tracer diffusion coefficient describing transport along nano-/microscaled YSZ/Sc2O3 multilayers as a function of the thick-ness of the ion-conducting YSZ layers has been measured by isotope exchange depth profiling (IEDP), using secondary ion mass spec-trometry (SIMS). The multilayer samples were prepared by pulsed laser deposition (PLD) on (0001) Al2O3 single crystalline substrates. The values for the oxygen tracer diffusion coefficient were analyzed as a combination of contributions from bulk and interface contributions and compared with results from YSZ/Y2O3-multilayers with similar microstructure. Using the Nernst-Einstein equation as the relation between diffusivity and electrical conductivity we find very good agreement between conductivity and diffusion data, and we exclude substantial electronic conductivity in the multilayers. The effect of hetero-interface transport can be well explained by a simple interface strain model. As the multilayer samples consist of columnar film crystallites with a defined inter-face structure and texture, we also discuss the influence of this particular microstructure on the interfacial strain.
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Affiliation(s)
- Halit Aydin
- Physikalisch-Chemisches Institut, Justus-Liebig Universität Giessen, D-35390 Giessen, Germany
| | - Carsten Korte
- Institut für Energie und Klimaforschung (IEK-3: Brennstoffzellen), Forschungszentrum Jülich, D-52428 Jülich, Germany
| | - Jürgen Janek
- Physikalisch-Chemisches Institut, Justus-Liebig Universität Giessen, D-35390 Giessen, Germany
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26
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Hartmann P, Brezesinski T, Sann J, Lotnyk A, Eufinger JP, Kienle L, Janek J. Defect chemistry of oxide nanomaterials with high surface area: ordered mesoporous thin films of the oxygen storage catalyst CeO2-ZrO2. ACS NANO 2013; 7:2999-3013. [PMID: 23514447 DOI: 10.1021/nn400255w] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Herein we report the electrical transport properties of a series of ordered mesoporous ceria-zirconia (CexZr1-xO2, referred to as mp-CZO) thin films with both a cubic structure of (17±2) nm diameter pores and nanocrystalline walls. Samples over the whole range of composition, including bare CeO2 and ZrO2, were fabricated by templating strategies using the large diblock copolymer KLE as the structure-directing agent. Both the nanoscale structure and the chemical composition of the mesoporous materials were analyzed by a combination of scanning and transmission electron microscopy, grazing incidence small-angle X-ray scattering, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. The total conductivity as a function of the film composition, temperature, and oxygen partial pressure was measured using impedance spectroscopy. The mesoporous solid solutions of CeO2-ZrO2 prepared in this work showed a higher stability against thermal ripening than both binary oxides, making them ideal model systems to study both the charge transport properties and the oxygen storage at elevated temperatures. We find that the redox properties of nanocrystalline mp-CZO thin films differ significantly from those of bulk CZO materials reported in the literature and, therefore, propose a defect chemical model of surface regions.
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Affiliation(s)
- Pascal Hartmann
- Physikalisch-Chemisches Institut, Justus-Liebig-Universität, Heinrich-Buff-Ring 58, 35392 Giessen, Germany
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27
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An J, Koh AL, Park JS, Sinclair R, Gür TM, Prinz FB. Aberration-Corrected TEM Imaging of Oxygen Occupancy in YSZ. J Phys Chem Lett 2013; 4:1156-1160. [PMID: 26282035 DOI: 10.1021/jz4002423] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present atomic-scale imaging of oxygen columns and show quantitative analysis on the occupancy of the columns in yttria-stabilized zirconia (YSZ) using aberration-corrected TEM operated under the negative Cs condition. Also, individual contributions both from oxygen column occupancy and the static displacement of oxygen atoms due to occupancy change to the observed column intensities of TEM images were systematically investigated using HRTEM simulation. We found that oxygen column intensity is governed primarily by column occupancy rather than by static displacement of oxygen atoms. Utilizing the aberration-corrected TEM capability and HRTEM simulation results, we experimentally verified that oxygen vacancies segregate near the single grain boundary of a YSZ bicrystal. The methodology and the high spatial resolution characterization tool employed in the present study provide insights into the distribution of oxygen vacancies in the bulk as well as near grain boundaries and pave the way for further investigation and atomic-scale analysis in other important oxide materials.
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Affiliation(s)
| | | | - Joong Sun Park
- §Environmental and Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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28
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Chao CC, Park JS, Tian X, Shim JH, Gür TM, Prinz FB. Enhanced oxygen exchange on surface-engineered yttria-stabilized zirconia. ACS NANO 2013; 7:2186-2191. [PMID: 23397972 DOI: 10.1021/nn305122f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Ion conducting oxides are commonly used as electrolytes in electrochemical devices including solid oxide fuel cells and oxygen sensors. A typical issue with these oxide electrolytes is sluggish oxygen surface kinetics at the gas-electrolyte interface. An approach to overcome this sluggish kinetics is by engineering the oxide surface with a lower oxygen incorporation barrier. In this study, we engineered the surface doping concentration of a common oxide electrolyte, yttria-stabilized zirconia (YSZ), with the help of atomic layer deposition (ALD). On optimizing the dopant concentration at the surface of single-crystal YSZ, a 5-fold increase in the oxygen surface exchange coefficient of the electrolyte was observed using isotopic oxygen exchange experiments coupled with secondary ion mass spectrometer measurements. The results demonstrate that electrolyte surface engineering with ALD can have a meaningful impact on the performance of electrochemical devices.
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Affiliation(s)
- Cheng-Chieh Chao
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States.
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29
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Gerstl M, Friedbacher G, Kubel F, Hutter H, Fleig J. The relevance of interfaces for oxide ion transport in yttria stabilized zirconia (YSZ) thin films. Phys Chem Chem Phys 2013; 15:1097-107. [DOI: 10.1039/c2cp42347b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Hinterberg J, Adams A, Blümich B, Heitjans P, Kim S, Munir ZA, Martin M. 1H-NMR measurements of proton mobility in nano-crystalline YSZ. Phys Chem Chem Phys 2013; 15:19825-30. [DOI: 10.1039/c3cp53039f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Aydin H, Korte C, Rohnke M, Janek J. Oxygen tracer diffusion along interfaces of strained Y2O3/YSZ multilayers. Phys Chem Chem Phys 2013; 15:1944-55. [DOI: 10.1039/c2cp43231e] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Gerstl M, Navickas E, Leitgeb M, Friedbacher G, Kubel F, Fleig J. The grain and grain boundary impedance of sol-gel prepared thin layers of yttria stabilized zirconia (YSZ). SOLID STATE IONICS 2012; 225:732-736. [PMID: 27570329 PMCID: PMC4986287 DOI: 10.1016/j.ssi.2012.02.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 01/30/2012] [Accepted: 02/06/2012] [Indexed: 06/06/2023]
Abstract
Separating grain and grain boundary impedance contributions of ion conducting thin films is a highly non-trivial task. Recently, it could be shown that long, thin, closely spaced, and interdigitally arranged electrodes enabled such a separation on pulsed laser deposited yttria stabilized zirconia (YSZ) thin films. In this contribution, the same approach was used to investigate YSZ layers prepared by the sol-gel route on sapphire substrates. Grain and grain boundary properties were quantified for layers between 28 and 168 nm thickness. Only for the thinnest of the investigated layers, a deviation from macroscopic bulk properties was found, which could be correlated to interfacial strain in the epitaxial layer. A dependence of the preferential orientation on the film thickness was found.
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Affiliation(s)
- M. Gerstl
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, 1060 Vienna, Austria
| | - E. Navickas
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, 1060 Vienna, Austria
- Institute of Materials Science, Kaunas University of Technology, Savanoriu 271, 50131 Kaunas, Lithuania
| | - M. Leitgeb
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, 1060 Vienna, Austria
| | - G. Friedbacher
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, 1060 Vienna, Austria
| | - F. Kubel
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, 1060 Vienna, Austria
| | - J. Fleig
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, 1060 Vienna, Austria
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33
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Gerstl M, Navickas E, Friedbacher G, Kubel F, Ahrens M, Fleig J. The separation of grain and grain boundary impedance in thin yttria stabilized zirconia (YSZ) layers. SOLID STATE IONICS 2011; 185:32-41. [PMID: 27570327 PMCID: PMC4986312 DOI: 10.1016/j.ssi.2011.01.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 12/10/2010] [Accepted: 01/14/2011] [Indexed: 05/19/2023]
Abstract
An improved electrode geometry is proposed to study thin ion conducting films by impedance spectroscopy. It is shown that long, thin, and closely spaced electrodes arranged interdigitally allow a separation of grain and grain boundary effects also in very thin films. This separation is shown to be successful for yttria stabilized zirconia (YSZ) layers thinner than 20 nm. In a series of experiments it is demonstrated that the extracted parameters correspond to the YSZ grain boundary and grain bulk resistances or to grain boundary and substrate capacitances. Results also show that our YSZ films produced by pulsed-laser deposition (PLD) on sapphire substrates exhibit a bulk conductivity which is very close to that of macroscopic YSZ samples.
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Affiliation(s)
- M. Gerstl
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
- Corresponding author. Tel.: +43 158801164150.
| | - E. Navickas
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
- Institute of Materials Science, Kaunas University of Technology, Savanoriu 271, 50131 Kaunas, Lithuania
| | - G. Friedbacher
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
| | - F. Kubel
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
| | - M. Ahrens
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
| | - J. Fleig
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
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34
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Gerstl M, Frömling T, Schintlmeister A, Hutter H, Fleig J. Measurement of 18O tracer diffusion coefficients in thin yttria stabilized zirconia films. SOLID STATE IONICS 2011; 184:23-26. [PMID: 27570326 PMCID: PMC4986288 DOI: 10.1016/j.ssi.2010.08.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 08/20/2010] [Accepted: 08/22/2010] [Indexed: 06/06/2023]
Abstract
In this paper we present a method to measure oxygen tracer diffusion coefficients in thin ion conducting films without being limited by slow oxygen incorporation kinetics. The method is based on a two step process. In the first step a substantial amount of 18O tracer is locally incorporated for example into an yttria stabilized zirconia (YSZ) layer at low temperatures with the aid of an electric current, thus overcoming slow thermal oxygen exchange while still limiting lateral diffusion to a minimum. In the second step controlled diffusion takes place at elevated temperatures in ultra high vacuum (UHV) to impede loss of tracer due to oxygen exchange at the film surface. In this second step the surface of the thin film may additionally be modified compared to the oxygen incorporation step. This allows to easily investigate effects of interfaces on ion transport. The achieved in-plane concentration profiles are then measured by secondary ion mass spectrometry (SIMS). Comparison with electrical measurements on YSZ thin films proves the applicability of the method.
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Affiliation(s)
- M. Gerstl
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
| | - T. Frömling
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
| | - A. Schintlmeister
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
| | - H. Hutter
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
| | - J. Fleig
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164/EC, 1060 Vienna, Austria
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35
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Sankaranarayanan SKRS, Ramanathan S. Interface proximity effects on ionic conductivity in nanoscale oxide-ion conducting yttria stabilized zirconia: An atomistic simulation study. J Chem Phys 2011; 134:064703. [DOI: 10.1063/1.3549891] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Schäfer M, Weitzel KM. Bombardment induced ion transport. Part I: Numerical investigation of bombardment induced ion transport through glasses and membranes on the basis of the Nernst–Planck–Poisson equations. Phys Chem Chem Phys 2011; 13:20112-22. [DOI: 10.1039/c1cp21215j] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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38
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Kim S, Jain P, Avila-Paredes HJ, Thron A, van Benthem K, Sen S. Strong immobilization of charge carriers near the surface of a solid oxide electrolyte. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b926664j] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Avila-Paredes HJ, Barrera-Calva E, Anderson HU, De Souza RA, Martin M, Munir ZA, Kim S. Room-temperature protonic conduction in nanocrystalline films of yttria-stabilized zirconia. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm00051e] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Garcia-Barriocanal J, Rivera-Calzada A, Varela M, Sefrioui Z, Díaz-Guillén MR, Moreno KJ, Díaz-Guillén JA, Iborra E, Fuentes AF, Pennycook SJ, Leon C, Santamaria J. Tailoring disorder and dimensionality: strategies for improved solid oxide fuel cell electrolytes. Chemphyschem 2009; 10:1003-11. [PMID: 19330781 DOI: 10.1002/cphc.200800691] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Reducing the operation temperature of solid oxide fuel cells is a major challenge towards their widespread use for power generation. This has triggered an intense materials research effort involving the search for novel electrolytes with higher ionic conductivity near room temperature. Two main directions are being currently followed: the use of doping strategies for the synthesis of new bulk materials and the implementation of nanotechnology routes for the fabrication of artificial nanostructures with improved properties. In this paper, we review our recent work on solid oxide fuel cell electrolyte materials in these two directions, with special emphasis on the importance of disorder and reduced dimensionality in determining ion conductivity. Substitution of Ti for Zr in the A(2)Zr(2-) (y)Ti(y)O(7) (A = Y, Dy, and Gd) series, directly related to yttria stabilized zirconia (a common fuel cell electrolyte), allows controlling ion mobility over wide ranges. In the second scenario we describe the strong enhancement of the conductivity occurring at the interfaces of superlattices made by alternating strontium titanate and yttria stabilized zirconia ultrathin films. We conclude that cooperative effects in oxygen dynamics play a primary role in determining ion mobility of bulk and artificially nanolayered materials and should be considered in the design of new electrolytes with enhanced conductivity.
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41
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Guo X, Maier J. Ionically Conducting Two-Dimensional Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2009; 21:2619-2631. [PMID: 36751062 DOI: 10.1002/adma.200900412] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 04/02/2009] [Indexed: 06/18/2023]
Abstract
In the context of revealing interfacial effects on ion conduction, thin films are extremely worthwhile due to defined geometry. Of particular interest are heterostructures as they offer symmetric boundary conditions and a high density of hetero-interfaces. The recent progress in this field is reviewed. Materials classes under concern include halides and oxides, and refer to various degrees of disorder and different mobilities. Even though in its infancy, the field of ionic heterostructures is already characterized by a variety of results of fundamental importance and of technological relevance.
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Affiliation(s)
- Xiangxin Guo
- Key Laboratory of Transparent and Opto-functional Inorganic Materials Shanghai Institute of Ceramics, Chinese Academy of Sciences 1295 Ding Xi Road, Shanghai 200050 (P. R. China)
| | - Joachim Maier
- Max-Planck-Institut für Festkörperforschung Heisenbergstr. 1, 70569 Stuttgart (Germany)
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42
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Allen JP, Greń W, Molinari M, Arrouvel C, Maglia F, Parker SC. Atomistic modelling of adsorption and segregation at inorganic solid interfaces. MOLECULAR SIMULATION 2009. [DOI: 10.1080/08927020902774570] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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43
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Avila-Paredes HJ, Choi K, Chen CT, Kim S. Dopant-concentration dependence of grain-boundary conductivity in ceria: A space-charge analysis. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b904583j] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Ruprecht B, Wilkening M, Feldhoff A, Steuernagel S, Heitjans P. High anion conductivity in a ternary non-equilibrium phase of BaF2 and CaF2 with mixed cations. Phys Chem Chem Phys 2009; 11:3071-81. [DOI: 10.1039/b901293a] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Kim S, Avila-Paredes HJ, Wang S, Chen CT, De Souza RA, Martin M, Munir ZA. On the conduction pathway for protons in nanocrystalline yttria-stabilized zirconia. Phys Chem Chem Phys 2009; 11:3035-8. [DOI: 10.1039/b901623f] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Korte C, Peters A, Janek J, Hesse D, Zakharov N. Ionic conductivity and activation energy for oxygen ion transport in superlattices—the semicoherent multilayer system YSZ (ZrO2 + 9.5 mol% Y2O3)/Y2O3. Phys Chem Chem Phys 2008; 10:4623-35. [DOI: 10.1039/b801675e] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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