Understanding electrochemical properties of materials by imaging their crystal structure

Susana Garcia-Martin^a

^aComplutense University of Madrid, Calle del Profesor José García Santesmases, Madrid, Spain

Proceedings of 24th International Conference on Solid State Ionics (SSI24)

Advanced characterisation techniques: fundamental and devices

London, United Kingdom, 2024 July 14th - 19th

Organizers: John Kilner and Stephen Skinner

Keynote, Susana Garcia-Martin, presentation 065
Publication date: 10th April 2024

Advanced techniques for structural and microstructural characterization of materials are powerful tools to understand their fundamental properties. In the chase for higher resolution to understand the atomic origins of functional properties of oxides, scanning transmission electron microscopy (STEM) provides substantial advantages. However, in the cases under study, basic crystallography prior to the use of these advanced techniques is mandatory to completely solve the crystal structure of the materials. The electron diffraction (ED) patterns reflect the unit cell symmetry. The relations between the reciprocal and real space, by interpretation of the ED patterns in combination with the corresponding TEM images, permit to conclude the basic crystallographic parameters. The combination of high angle annular dark field STEM (HAADF-STEM) images, also called Z-contrast images, and the electron energy loss spectroscopy (EELS) mapping from single atomic columns selected from the image, allows the locations of the cations (the heaviest atoms) in the crystal structure highlighting compositional modulations, while images taken in annular bright field mode (ABF-STEM) reveal the positions of the lighter atoms of the materials, the oxygen atoms in the case of oxides.

The crystal structure of a variety of (A/A’)_nB_nO_3n−_δ oxides with electrocatalytic properties for oxygen reduction reaction (ORR) has been solved by ED, HRTEM, STEM (HAADF and ABF modes) and EELS mapping [1], [2], [3], [4], [5], [6]. Strong relations between the ordering of the A cations, the coordination polyhedra around the B atoms and the location of the anion vacancies, with the properties and experimental behaviour of these materials are established. The nature of the B atoms highly affects the oxygen content and location of anion vacancies within the crystal structure, which deeply impact on the electrochemical properties of the materials.

References:

[1] Muñoz-Gil, D.; Pérez-Coll, D.; D.; Ávila-Brande, D.; Urones-Garrote, E.; García-Martín, S. Ordering effects in the crystal structure and electrochemical properties of the Gd0.5Ba0.5Mn0.5Fe0.5O3−δ perovskite. Dalton Trans. 2015, 44, 10867–10874.

[2] Martínez de Irujo-Labalde, X.; Muñoz-Gil, D.; Ávila-Brande, D.; Urones-Garrote, E.; García-Martín, S. Complex modulation of the crystal structure of a layered perovskite. A promising solid-oxide-fuel-cell cathode. J. Mater. Chem. A 2016, 4, 10241-10247.

[3] Muñoz-Gil, D.; Pérez-Coll, D.; Urones-Garrote, E.; Amador, U.; García-Martín, S. Influence of the synthesis conditions on the crystal structure and properties of GdBaCo2-xFexO5+δ oxides as air-electrodes for Intermediate Temperature Solid Oxide Fuel Cells. J. Mater. Chem. A 2017, 5, 12550–12556.

[4] Muñoz-Gil, D.; Urones-Garrote, E.; Pérez-Coll, D.; Amador, U.; García-Martín, S. Crystal structure and compositional effects on the electrical and electrochemical properties of GdBaCo2-xMnxO5+δ (0 ≤ x ≤ 2) oxides for use as air-electrodes in solid oxide fuel cells. J. Mater. Chem. A 2018, 6, 5452-5460.

[5] Marín-Gamero, R.; Martínez de Irujo-Labalde, X.; Urones-Garrote, E.; García-Martín, S. Structural Ordering Supremacy on the Oxygen Reduction Reaction of Layered Iron-Perovskites. Inorganic Chemistry 2020, 59, 5529-5537.

[6] Amador, U.; Marín-Gamero, R.; Ritter, C.; Fabelo, O.; Azcondo, M.T.; García-Martín, S. Stability and Evolution of the Crystal Structure of TbBaCo2O6−δ during Thermal Oxygen Release/Uptake. Inorganic Chemistry 2023, 62, 247−255.

Acknowledgements:

The author thanks MCIN/AEI/10.13039/501100011033 for funding the Project PID2022-139039OB-C22 and the “NextGenerationEU”/PRTR Project TED2021-130452B-C2. The author also thanks to the MCIN and Comunidad de Madrid for funding the “NextGenerationEU”/PRTR Project GREENH2-CM.

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.