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Kante MV, Nilayam ARL, Hahn H, Bhattacharya SS, Elm MT, Velasco L, Botros M. Elucidation of the Transport Properties of Calcium-Doped High Entropy Rare Earth Aluminates for Solid Oxide Fuel Cell Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2309735. [PMID: 38618655 DOI: 10.1002/smll.202309735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/30/2024] [Indexed: 04/16/2024]
Abstract
Solid oxide fuel cells (SOFCs) are paving the way to clean energy conversion, relying on efficient oxygen-ion conductors with high ionic conductivity coupled with a negligible electronic contribution. Doped rare earth aluminates are promising candidates for SOFC electrolytes due to their high ionic conductivity. However, they often suffer from p-type electronic conductivity at operating temperatures above 500 °C under oxidizing conditions caused by the incorporation of oxygen into the lattice. High entropy materials are a new class of materials conceptualized to be stable at higher temperatures due to their high configurational entropy. Introducing this concept to rare earth aluminates can be a promising approach to stabilize the lattice by shifting the stoichiometric point of the oxides to higher oxygen activities, and thereby, reducing the p-type electronic conductivity in the relevant oxygen partial pressure range. In this study, the high entropy oxide (Gd,La,Nd,Pr,Sm)AlO3 is synthesized and doped with Ca. The Ca-doped (Gd,La,Nd,Pr,Sm)AlO3 compounds exhibit a higher ionic conductivity than most of the corresponding Ca-doped rare earth aluminates accompanied by a reduction of the p-type electronic conductivity contribution typically observed under oxidizing conditions. In light of these findings, this study introduces high entropy aluminates as a promising candidate for SOFC electrolytes.
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Affiliation(s)
- Mohana V Kante
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Kaiserstr. 12, 76131, Karlsruhe, Germany
| | - Ajai R Lakshmi Nilayam
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Kaiserstr. 12, 76131, Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
| | - Horst Hahn
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Kaiserstr. 12, 76131, Karlsruhe, Germany
- Department of Chemical, Biological and Materials Engineering, The University of Oklahoma, 100 E. Boyd St., Norman, OK, 73019, USA
| | - Subramshu S Bhattacharya
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Matthias T Elm
- Center for Materials Research, Institute of Experimental Physics I, and Institute of Physical Chemistry, Justus-Liebig-Universität Gießen, 35392, Gießen, Germany
| | - Leonardo Velasco
- Direccion academica, Universidad Nacional de Colombia sede de La Paz, Km 9 via Valledupar - La Paz, Cesar, 202010, Colombia
| | - Miriam Botros
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Kaiserstr. 12, 76131, Karlsruhe, Germany
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Hayashida M, Malac M. High-Energy Electron Scattering in Thick Samples Evaluated by Bright-Field Transmission Electron Microscopy, Energy-Filtering Transmission Electron Microscopy, and Electron Tomography. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-13. [PMID: 35343421 DOI: 10.1017/s1431927622000472] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Energy-filtering transmission electron microscopy (TEM) and bright-field TEM can be used to extract local sample thickness $t$ and to generate two-dimensional sample thickness maps. Electron tomography can be used to accurately verify the local $t$. The relations of log-ratio of zero-loss filtered energy-filtering TEM beam intensity ($I_{{\rm ZLP}}$) and unfiltered beam intensity ($I_{\rm u}$) versus sample thickness $t$ were measured for five values of collection angle in a microscope equipped with an energy filter. Furthermore, log-ratio of the incident (primary) beam intensity ($I_{\rm p}$) and the transmitted beam $I_{{\rm tr}}$ versus $t$ in bright-field TEM was measured utilizing a camera before the energy filter. The measurements were performed on a multilayer sample containing eight materials and thickness $t$ up to 800 nm. Local thickness $t$ was verified by electron tomography. The following results are reported:• The maximum thickness $t_{{\rm max}}$ yielding a linear relation of log-ratio, $\ln ( {I_{\rm u}}/{I_{{\rm ZLP}}})$ and $\ln ( {I_{\rm p}}/{I_{{\rm tr}}} )$, versus $t$.• Inelastic mean free path ($\lambda _{{\rm in}}$) for five values of collection angle.• Total mean free path ($\lambda _{{\rm total}}$) of electrons excluded by an angle-limiting aperture.• $\lambda _{{\rm in}}$ and $\lambda _{{\rm total}}$ are evaluated for the eight materials with atomic number from $\approx$10 to 79.The results can be utilized as a guide for upper limit of $t$ evaluation in energy-filtering TEM and bright-field TEM and for optimizing electron tomography experiments.
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Affiliation(s)
- Misa Hayashida
- Nanotechnology Research Centre, National Research Council, Edmonton, ABT6G 2M9, Canada
| | - Marek Malac
- Nanotechnology Research Centre, National Research Council, Edmonton, ABT6G 2M9, Canada
- Department of Physics, University of Alberta, Edmonton, ABT6G 2E1, Canada
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Materials characterisation by angle-resolved scanning transmission electron microscopy. Sci Rep 2016; 6:37146. [PMID: 27849001 PMCID: PMC5111052 DOI: 10.1038/srep37146] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 10/25/2016] [Indexed: 11/08/2022] Open
Abstract
Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1-x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1-x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16-255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.
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Egerton R, Mcleod R, Malac M. Validity of the dipole approximation in TEM-EELS studies. Microsc Res Tech 2014; 77:773-8. [DOI: 10.1002/jemt.22398] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 06/17/2014] [Indexed: 11/10/2022]
Affiliation(s)
- R.F. Egerton
- Physics Department; University of Alberta; Edmonton Canada T6G 2E1
| | - R.A. Mcleod
- Physics Department; University of Alberta; Edmonton Canada T6G 2E1
- National Institute for Nanotechnology; Edmonton Canada T6G 2M9
| | - M. Malac
- Physics Department; University of Alberta; Edmonton Canada T6G 2E1
- National Institute for Nanotechnology; Edmonton Canada T6G 2M9
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Vulović M, Franken E, Ravelli RB, van Vliet LJ, Rieger B. Precise and unbiased estimation of astigmatism and defocus in transmission electron microscopy. Ultramicroscopy 2012. [DOI: 10.1016/j.ultramic.2012.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Löffler S, Ennen I, Tian F, Schattschneider P, Jaouen N. Breakdown of the dipole approximation in core losses. Ultramicroscopy 2011; 111:1163-7. [PMID: 21741917 PMCID: PMC3268650 DOI: 10.1016/j.ultramic.2011.03.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 03/08/2011] [Accepted: 03/10/2011] [Indexed: 11/30/2022]
Abstract
The validity of the dipole approximations commonly used in the inelastic scattering theory for transmission electron microscopy is reviewed. Both experimental and numerical arguments are presented, emphasizing that the dipole approximations cause significant errors of the order of up to 25% even at small momentum transfer. This behavior is attributed mainly to non-linear contributions to the dynamic form factor due to the overlap of wave functions.
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Affiliation(s)
- S Löffler
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria.
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Herring R. Planar diffracted-beam interferometry/holography. Ultramicroscopy 2008; 108:688-97. [DOI: 10.1016/j.ultramic.2007.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 10/15/2007] [Accepted: 11/02/2007] [Indexed: 11/24/2022]
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Lozano-Perez S, Titchmarsh JM. EFTEM assistant: A tool to understand the limitations of EFTEM. Ultramicroscopy 2007; 107:313-21. [PMID: 17030440 DOI: 10.1016/j.ultramic.2006.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 08/14/2006] [Accepted: 08/24/2006] [Indexed: 11/16/2022]
Abstract
The first version of a free tool for Gatan's Digital Micrographtrade mark is presented which aims to aid the energy-filtered TEM (EFTEM) community by predicting and correcting the most common sources of degradation. The software allows selection of either Krivanek's or Egerton's approach to account for the spatial resolution degradation caused by the electron optical aberrations. The effects of aberrations and signal 'delocalization' are combined to simulate the blurring caused in EFTEM elemental maps. Two microstructural features with ideal geometry are used to illustrate use of the software: spherical particles and parallel sided interfaces. The software also allows the simulation of the effects of the noise and drift in the final elemental map, independently or in combination. It can be easily demonstrated that when the dimensions of the feature of interest are comparable in scale to the image degradation factors, the effects of the latter should not be neglected. More importantly, the software can deconvolute the effects of the degradation factors, revealing the true dimensions and signal intensity of the feature of interest.
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Affiliation(s)
- S Lozano-Perez
- Department of Materials, University of Oxford, Parks Rd, OX1 3PH Oxford, UK.
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Herring RA. Energy-filtered electron-diffracted beam holography. Ultramicroscopy 2005; 104:261-70. [PMID: 15996821 DOI: 10.1016/j.ultramic.2005.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 04/13/2005] [Accepted: 05/18/2005] [Indexed: 11/19/2022]
Abstract
A method of energy-filtered electron holography is described where any two electron-diffracted beams can be interfered using an electron biprism. A Gatan image filter is used to select the energy loss of the electrons produced in the holograms. Gallium arsenide is used as the TEM specimen. This method of microscopy confirms that fringes extending beyond a limiting aperture were due to inelastically scattered electrons and specifically electrons scattered from the bulk plasmon. The degree of coherence of the zero-loss and energy-loss electrons were high and measured to be approximately 0.3, which was maintained even for the high energy-loss electrons up to 100 eV. Future systematic studies using this method should help understand the Stobbs factor and contribute to the development of quantitative high-resolution electron microscopy.
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Affiliation(s)
- R A Herring
- Center for Advanced Materials and Related Technology, Department of Mechanical Engineering, University of Victoria, STN CSC, Victoria, BC, Canada, V8N 4T6.
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Walther T. Electron energy-loss spectroscopic profiling of thin film structures: 0.39 nm line resolution and 0.04 eV precision measurement of near-edge structure shifts at interfaces. Ultramicroscopy 2003; 96:401-11. [PMID: 12871804 DOI: 10.1016/s0304-3991(03)00104-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The method of energy-loss spectroscopic profiling of interfaces, planar defects and thin film structures in a transmission electron microscope with an imaging filter is introduced. Ways to calculate true chemical profiles with near-atomic line resolution are described. An application to the perovskite system (La,Ca)MnO(3)/SrTiO(3) demonstrates that the technical merit of this method is the simultaneous achievement of high resolution (down to 0.39nm line resolution), high chemical sensitivity (around 1at% standard deviation) and very high precision in the measurement of shifts of edge onsets and energy-loss near-edge structure details (down to 0.04eV). The combination of these characteristics makes the method a powerful tool for the quantification of diffusion and segregation of elements on the atomic scale in a variety of materials systems.
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Affiliation(s)
- T Walther
- Department of Inorganic Chemistry, University of Bonn, Römerstrasse 164, Bonn D-53117, Germany.
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Assessment of electron energy-loss spectroscopy below 5 eV in semiconductor materials in a VG STEM. Ultramicroscopy 1997. [DOI: 10.1016/s0304-3991(97)00025-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Josefsson TW, Cobal RL, Allen LJ. Dielectric matrix calculation of the differential cross section for plasmon excitation and application to electron diffraction. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:12873-12879. [PMID: 9985145 DOI: 10.1103/physrevb.54.12873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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