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Wollstadt S, Clemens O. On the Impact of the Degree of Fluorination on the ORR Limiting Processes within Iron Based Catalysts: A Model Study on Symmetrical Films of Barium Ferrate. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E2532. [PMID: 32503126 PMCID: PMC7321444 DOI: 10.3390/ma13112532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/25/2020] [Accepted: 05/28/2020] [Indexed: 12/21/2022]
Abstract
In this study, symmetrical films of BaFeO2.67, BaFeO2.33F0.33 and BaFeO2F were synthesized and the oxygen uptake and conduction was investigated by high temperature impedance spectroscopy under an oxygen atmosphere. The data were analyzed on the basis of an impedance model designed for highly porous mixed ionic electronic conducting (MIEC) electrodes. Variable temperature X-ray diffraction experiments were utilized to estimate the stability window of the oxyfluoride compounds, which yielded a degradation temperature for BaFeO2.33F0.33 of 590 °C and a decomposition temperature for BaFeO2F of 710 °C. The impedance study revealed a significant change of the catalytic behavior in dependency of the fluorine content. BaFeO2.67 revealed a bulk-diffusion limited process, while BaFeO2.33F0.33 appeared to exhibit a fast bulk diffusion and a utilization region δ larger than the electrode thickness L (8 μm). In contrast, BaFeO2F showed very area specific resistances due to the lack of oxygen vacancies. The activation energy for the uptake and conduction process of oxygen was found to be 0.07/0.29 eV (temperature range-dependent), 0.33 eV and 0.67 eV for BaFeO2.67, BaFeO2.33F0.33 and BaFeO2F, respectively.
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Affiliation(s)
- Stephan Wollstadt
- Fachgebiet Materialdesign Durch Synthese, Institut für Materialwissenschaft, Technical University of Darmstadt, 64287 Darmstadt, Germany;
| | - Oliver Clemens
- Fachgebiet Materialdesign Durch Synthese, Institut für Materialwissenschaft, Technical University of Darmstadt, 64287 Darmstadt, Germany;
- Institut für Nanotechnologie, Karlsruher Institut für Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein Leopoldshafen, Germany
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2
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López-Vergara A, Bergillos-Ruiz M, Zamudio-García J, Porras-Vázquez JM, Canales-Vazquez J, Marrero-López D, Losilla ER. Synergic Effect of Metal and Fluorine Doping on the Structural and Electrical Properties of La 5.4MoO 11.1-Based Materials. Inorg Chem 2020; 59:1444-1452. [PMID: 31910003 DOI: 10.1021/acs.inorgchem.9b03194] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cationic and anionic frameworks of La5.4MoO11.1 proton conductors have been modified by means of metal (Ti4+, Zr4+, and Nb5+) and fluorine (F-) doping. This synergic effect leads to the stabilization of high-symmetry and single-phase polymorphs. The materials have been fully characterized by structural techniques, such as X-ray and neutron powder diffraction and transmission electron microscopy. The fluorine content was determined by ion chromatography. Impedance spectroscopy analysis under different atmospheres (dry and wet N2 and O2 and wet 5% H2-Ar) showed an improvement in the electronic conductivity under reducing conditions, making these materials potential candidates for hydrogen separation membranes.
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Affiliation(s)
- Adrián López-Vergara
- Universidad de Málaga , Dpto. de Química Inorgánica, Cristalografía y Mineralogía , 29071 Málaga , Spain
| | - Marta Bergillos-Ruiz
- Universidad de Málaga , Dpto. de Química Inorgánica, Cristalografía y Mineralogía , 29071 Málaga , Spain
| | - Javier Zamudio-García
- Universidad de Málaga , Dpto. de Química Inorgánica, Cristalografía y Mineralogía , 29071 Málaga , Spain
| | - José M Porras-Vázquez
- Universidad de Málaga , Dpto. de Química Inorgánica, Cristalografía y Mineralogía , 29071 Málaga , Spain
| | - Jesús Canales-Vazquez
- Renewable Energy Research Institute , University of Castilla-La Mancha , 02071 Albacete , Spain
| | | | - Enrique R Losilla
- Universidad de Málaga , Dpto. de Química Inorgánica, Cristalografía y Mineralogía , 29071 Málaga , Spain
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Nair A, Wollstadt S, Witte R, Dasgupta S, Kehne P, Alff L, Komissinskiy P, Clemens O. Synthesis and characterisation of fluorinated epitaxial films of BaFeO2F: tailoring magnetic anisotropyviaa lowering of tetragonal distortion. RSC Adv 2019; 9:37136-37143. [PMID: 35542307 PMCID: PMC9075590 DOI: 10.1039/c9ra08039b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 10/25/2019] [Indexed: 01/11/2023] Open
Abstract
In this article, we report on the synthesis and characterisation of fluorinated epitaxial films of BaFeO2F via low-temperature fluorination of thin films of BaFeO2.5+d grown by pulsed laser deposition. Diffraction measurements show that fluoride incorporation only results in a contraction of the film perpendicular to the film surface, where clamping by the substrate is prohibitive for strong in-plane changes. The fluorinated films were found to be homogenous regarding the fluorine content over the whole film thickness, and can be considered as single crystal equivalents to the bulk phase BaFeO2F. Surprisingly, fluorination resulted in the change of the tetragonal distortion to a nearly cubic symmetry, which results in a lowering of anisotropic orientation of the magnetic moments of the antiferromagnetically ordered compound, confirmed by Mössbauer spectroscopy and magnetic studies. Fluorination of epitaxially grown thin films of BaFeO2.5 to BaFeO2F results in increased magnetic anisotropy.![]()
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Affiliation(s)
- Akash Nair
- Technische Universität Darmstadt
- Institute of Materials Science
- Materials Design by Synthesis Division
- 64287 Darmstadt
- Germany
| | - Stephan Wollstadt
- Technische Universität Darmstadt
- Institute of Materials Science
- Materials Design by Synthesis Division
- 64287 Darmstadt
- Germany
| | - Ralf Witte
- Karlsruhe Institute of Technology
- Institute of Nanotechnology
- 76344 Eggenstein Leopoldshafen
- Germany
| | - Supratik Dasgupta
- Technische Universität Darmstadt
- Institute of Materials Science
- Advanced Thin Film Technology Division
- 64287 Darmstadt
- Germany
| | - Philipp Kehne
- Technische Universität Darmstadt
- Institute of Materials Science
- Advanced Thin Film Technology Division
- 64287 Darmstadt
- Germany
| | - Lambert Alff
- Technische Universität Darmstadt
- Institute of Materials Science
- Advanced Thin Film Technology Division
- 64287 Darmstadt
- Germany
| | - Philipp Komissinskiy
- Technische Universität Darmstadt
- Institute of Materials Science
- Advanced Thin Film Technology Division
- 64287 Darmstadt
- Germany
| | - Oliver Clemens
- Technische Universität Darmstadt
- Institute of Materials Science
- Materials Design by Synthesis Division
- 64287 Darmstadt
- Germany
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4
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Clemens O, Reitz C, Witte R, Kruk R, Smith RI. Anion ordering, magnetic structure and properties of the vacancy ordered perovskite Ba3Fe3O7F. J SOLID STATE CHEM 2016. [DOI: 10.1016/j.jssc.2016.07.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Clemens O, Marco JF, Thomas MF, Forder SD, Zhang H, Cartenet S, Monze A, Bingham PA, Slater PR, Berry FJ. Magnetic interactions in cubic-, hexagonal- and trigonal-barium iron oxide fluoride, BaFeO2F. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:346001. [PMID: 27355806 DOI: 10.1088/0953-8984/28/34/346001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
(57)Fe Mössbauer spectra have been recorded from the hexagonal (6H)- and trigonal (15R)- modifications of BaFeO2F and are compared with those previously recorded from the cubic form of BaFeO2F. The spectra, recorded over a temperature range from 15 to 650 K show that all of the iron in all the compounds is in the Fe(3+) state. Spectra from the 6H- and 15R-modifications were successfully fitted with components that were related to the Fe(1) and Fe(2) structural sites in the 6H variant and to the Fe(1), Fe(2) and Fe(3) structural sites in the 15R form. The magnetic ordering temperatures were determined as 597 ± 3 K for 6H-BaFeO2F and 636 ± 3 K for 15R-BaFeO2F. These values are surprisingly close to the value of 645 ± 5 K determined for the cubic form. The magnetic interactions in the three forms are compared with a view to explaining this similarity of magnetic ordering temperature.
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Affiliation(s)
- Oliver Clemens
- School of Chemistry, The University of Birmingham, Birmingham B15 2TT, UK. Technical University of Darmstadt, Joint Research Laboratory Nanomaterials, Jovanka-Bontschits-Straße 2, 64287 Darmstadt, Germany. Karlsruhe Institute of Technology, Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Serrador L, Hernando M, Martínez JL, González-Calbet JM, Varela A, García-García FJ, Parras M. Chlorine Insertion Promoting Iron Reduction in Ba–Fe Hexagonal Perovskites: Effect on the Structural and Magnetic Properties. Inorg Chem 2016; 55:6261-70. [DOI: 10.1021/acs.inorgchem.6b00893] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Laura Serrador
- Departamento de Química Inorgánica,
Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - María Hernando
- Departamento de Química Inorgánica,
Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - José L. Martínez
- Instituto de Ciencia de Materiales, CSIC, Cantoblanco 28049 Madrid, Spain
| | - José M. González-Calbet
- Departamento de Química Inorgánica,
Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Centro Nacional de Microscopía Electrónica CNME, 28040 Madrid, Spain
| | - Aurea Varela
- Departamento de Química Inorgánica,
Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | | | - Marina Parras
- Departamento de Química Inorgánica,
Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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Cambaz MA, Vinayan BP, Clemens O, Munnangi AR, Chakravadhanula VSK, Kübel C, Fichtner M. Vanadium Oxyfluoride/Few-Layer Graphene Composite as a High-Performance Cathode Material for Lithium Batteries. Inorg Chem 2016; 55:3789-96. [DOI: 10.1021/acs.inorgchem.5b02687] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Musa Ali Cambaz
- Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU), Helmholtzstr. 11, 89081 Ulm, Germany
| | - B. P. Vinayan
- Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU), Helmholtzstr. 11, 89081 Ulm, Germany
| | - Oliver Clemens
- Institute
of Nanotechnology, Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany
- Joint Research Laboratory Nanomaterials, Technische Universität Darmstadt, Jovanka-Bontschits-Straße 2, 64287 Darmstadt, Germany
| | - Anji Reddy Munnangi
- Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU), Helmholtzstr. 11, 89081 Ulm, Germany
| | | | - Christian Kübel
- Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU), Helmholtzstr. 11, 89081 Ulm, Germany
- Institute
of Nanotechnology, Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Maximilian Fichtner
- Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU), Helmholtzstr. 11, 89081 Ulm, Germany
- Institute
of Nanotechnology, Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany
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Li B, Woods J, Siewenie J, Hah HY, Johnson JA, Johnson CE, Louca D. The magnetic and crystal structures of Sr1−δFeO2−xFx, a new oxyfluoride. Chem Commun (Camb) 2016; 52:2386-9. [DOI: 10.1039/c5cc04497a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A new quasi-two-dimensional oxyfluoride, Sr1−δFeO2−xFx, has been successfully synthesized by combining topotactic fluoridation and CaH2 reduction.
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Affiliation(s)
- Bing Li
- Department of Physics
- University of Virginia
- Charlottesville
- USA
| | - John Woods
- Department of Physics
- University of Virginia
- Charlottesville
- USA
| | - Joan Siewenie
- Spallation Neutron Source
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | - Hien-Yoong Hah
- Mechanical
- Aerospace and Biomedical Engineering
- University of Tennessee Space Institute
- Tullahoma
- USA
| | - Jacqueline A. Johnson
- Mechanical
- Aerospace and Biomedical Engineering
- University of Tennessee Space Institute
- Tullahoma
- USA
| | - Charles E. Johnson
- Center for Laser Applications
- University of Tennessee Space institute
- Tullahoma
- USA
| | - Despina Louca
- Department of Physics
- University of Virginia
- Charlottesville
- USA
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Structural characterization of a new vacancy ordered perovskite modification found for Ba3Fe3O7F (BaFeO2.333F0.333): Towards understanding of vacancy ordering for different perovskite-type ferrites. J SOLID STATE CHEM 2015. [DOI: 10.1016/j.jssc.2014.12.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Clemens O, Berry FJ, Wright AJ, Knight KS, Perez-Mato J, Igartua J, Slater PR. Reply to “Structural and magnetic behavior of the cubic oxyfluoride SrFeO2F studied by neutron diffraction”. J SOLID STATE CHEM 2015. [DOI: 10.1016/j.jssc.2015.02.022] [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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Clemens O, Kruk R, Patterson EA, Loho C, Reitz C, Wright AJ, Knight KS, Hahn H, Slater PR. Introducing a large polar tetragonal distortion into Ba-doped BiFeO3 by low-temperature fluorination. Inorg Chem 2014; 53:12572-83. [PMID: 25383956 DOI: 10.1021/ic502183t] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This article reports on the synthesis and crystallographic and magnetic structure of barium-doped BiFeO3 compounds with approximate composition Bi(1-x)Ba(x)FeO(3-x/2), as well as those of the fluorinated compounds Bi(1-x)Ba(x)FeO(3-x)F(x) (both with x = 0.2, 0.3), prepared by low-temperature fluorination of the oxide precursors using polyvinylidenedifluoride. Whereas the oxide compounds were obtained as cubic (x = 0.2) and slightly tetragonal (x = 0.3, c/a ≈ 1.003) distorted perovskite compounds, a large tetragonal polar distortion was observed for the oxyfluoride compounds (c/a ≈ 1.08 for x = 0.2 and ∼1.05 for x = 0.3), being isostructural to tetragonal PbTiO3. Although described differently in previous reports on Ba-doped BiFeO3, the observed remanent magnetization is found to agree well with the amount of BaFe12O19 only detectable by neutron diffraction and the well-known magnetic properties of BaFe12O19. The oxyfluoride compounds show G-type antiferromagnetic ordering with magnetic moments lying in the a/b plane.
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Affiliation(s)
- Oliver Clemens
- Joint Research Laboratory Nanomaterials and ‡Institute of Materials Science, Technische Universität Darmstadt , Jovanka-Bontschits-Straße 2, 64287 Darmstadt, Germany
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12
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Clemens O, Rongeat C, Reddy MA, Giehr A, Fichtner M, Hahn H. Electrochemical fluorination of perovskite type BaFeO2.5. Dalton Trans 2014; 43:15771-8. [DOI: 10.1039/c4dt02485k] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Clemens O, Gröting M, Witte R, Perez-Mato JM, Loho C, Berry FJ, Kruk R, Knight KS, Wright AJ, Hahn H, Slater PR. Crystallographic and magnetic structure of the perovskite-type compound BaFeO2.5: unrivaled complexity in oxygen vacancy ordering. Inorg Chem 2014; 53:5911-21. [PMID: 24901981 DOI: 10.1021/ic402988y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report here on the characterization of the vacancy-ordered perovskite-type structure of BaFeO2.5 by means of combined Rietveld analysis of powder X-ray and neutron diffraction data. The compound crystallizes in the monoclinic space group P2(1)/c [a = 6.9753(1) Å, b = 11.7281(2) Å, c = 23.4507(4) Å, β = 98.813(1)°, and Z = 28] containing seven crystallographically different iron atoms. The coordination scheme is determined to be Ba7(FeO4/2)1(FeO3/2O1/1)3(FeO5/2)2(FeO6/2)1 = Ba7Fe([6])1Fe([5])2Fe([4])4O17.5 and is in agreement with the (57)Fe Mössbauer spectra and density functional theory based calculations. To our knowledge, the structure of BaFeO2.5 is the most complicated perovskite-type superstructure reported so far (largest primitive cell, number of ABX2.5 units per unit cell, and number of different crystallographic sites). The magnetic structure was determined from the powder neutron diffraction data and can be understood in terms of "G-type" antiferromagnetic ordering between connected iron-containing polyhedra, in agreement with field-sweep and zero-field-cooled/field-cooled measurements.
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Affiliation(s)
- Oliver Clemens
- Joint Research Laboratory Nanomaterials and §Fachgebiet Materialmodellierung, Technische Universität Darmstadt , Jovanka-Bontschits-Straße 2, 64287 Darmstadt, Germany
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Clemens O, Berry FJ, Wright AJ, Knight KS, Perez-Mato J, Igartua J, Slater PR. A neutron diffraction study and mode analysis of compounds of the system La1−xSrxFeO3−xFx (x=1, 0.8, 0.5, 0.2) and an investigation of their magnetic properties. J SOLID STATE CHEM 2013. [DOI: 10.1016/j.jssc.2013.08.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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