Various structural families have been reported to support oxide ion conductivity; among these, perovskite conductors have received particular attention. The perovskite structure is generally composed of a framework of corner-sharing octahedral units. When the octahedral units share their faces, hexagonal perovskites are formed. Mixed combinations of corner-sharing and face-sharing octahedral units can give rise to a variety of hexagonal perovskite derivatives. However, the ionic conducting properties of these materials have not been well explored. In this feature article, we review the conducting properties of the most significant hexagonal perovskite derivatives, with special focus on Ba3MM'O8.5. Ba3MM'O8.5 is the first hexagonal perovskite derivative to exhibit substantial oxide ion conductivity, and here we outline the structural features that are key for the oxide ion conduction within this system. The results demonstrate that further investigation of hexagonal perovskite derivatives could open up new directions in the design of oxide ion conductors.
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http://dx.doi.org/10.1039/c8cc09534e | DOI Listing |
Chem Sci
January 2025
School of Physics and Optoelectronic Engineering, Foshan University Foshan 528000 China
Perovskite nanocrystals (NCs) with their excellent optical and semiconductor properties have emerged as primary candidates for optoelectronic applications. While extensive research has been conducted on the 3D perovskite phase, the zero-dimensional (0D) form of this promising material in the NC format remains elusive. In this paper, a new synthesis strategy is proposed.
View Article and Find Full Text PDFMolecules
December 2024
Department of Chemistry, Faculty of Natural Sciences, Kazakh National Women's Teacher Training University, Gogol 114/1, Almaty 050000, Kazakhstan.
This article presents the synthesis, electrophysical, and catalytic properties of a LaMnO-LaFeO nanocomposite material. The nanocomposite was synthesized via the sol-gel (Pechini) method. X-ray diffraction (XRD) analysis revealed a polycrystalline, biphasic perovskite structure combining both hexagonal and cubic symmetry.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK.
Negative thermal expansion is known to exist in a range of structure types but is extremely rare in hexagonal perovskites. Here we demonstrate that BaIrO displays negative linear thermal expansion in the direction of its face-shared IrO trimers, and apparent zero volume thermal expansion below 100 K. We present evidence that this anomalous thermal expansion is driven by an unusual form of rigid body phonon behaviour governed by the effective trimer valence state and therefore has structural and electronic components to the underlying mechanism.
View Article and Find Full Text PDFInorg Chem
December 2024
Materials, Chemical, and Computational Sciences Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
To synthetically target a specific material with select performance, the underlying relationship between structure and function must be understood. For targeting magnetic properties, such understanding is underdeveloped for a relatively new class of layered hexagonal perovskites, the 12R-BaMnO family. Here, we perform a detailed magnetostructural study of the layered hexagonal perovskite materials 12R-BaMnO, where = diamagnetic Ce or paramagnetic ≈ 1/2 Pr.
View Article and Find Full Text PDFInorg Chem
December 2024
Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
To systematically investigate the influence of the number of [AO] layers in the unit cell of hexagonal perovskite oxide on the oxygen evolution reaction performance, we successfully synthesized the three new hexagonal perovskite oxides 2H-BaCoRuO, 6H-BaCoRuO, and 10H-BaCoRuO with the same element composition but different [BaO] layers via the sol-gel method. Here, 2H, 6H, and 10H refer to the number of [BaO] layers contained in the unit cell of the BaCoRuO system. Experimentally, 10H-BaCoRuO, featuring ten layers of [BaO], exhibits optimal electrochemical activity among the three oxide catalysts, and in situ Raman results under various bias voltages confirm its ability to maintain a high surface crystal structural stability.
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