Atomic-scale insight into the oxygen ionic transport mechanisms in La₂NiO₄-based materials

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• 作者：E.N. Naumovich ; V.V. Kharton
• 关键词：Molecular dynamics ; Atomistic computer simulations ; Ionic conduction ; Lanthanum nickelate ; Ruddlesden-Popper family ; K₂NiF₄-type compounds
• 刊名：Journal of Molecular Structure: THEOCHEM
• 出版年：2010
• 出版时间：30 April 2010
• 年：2010
• 卷：946
• 期：1-3
• 页码：57-64
• 全文大小：659 K

文摘

The computer simulation studies employing both static lattice and molecular dynamics (MD) methods, were used to identify anion migration pathways, relevant energetic parameters and effects of the transition metal cation dopants on oxygen ion transport in La₂Ni(M)O_4+δ (M = Fe, Co, Cu) solid solutions, a family of promising oxide materials for fuel cell electrodes and dense ceramic membranes for oxygen separation. The factors related to different oxygen sublattices in the K₂NiF₄-type structure of La₂Ni(M)O_4+δ were appraised analyzing the MD data. The results show, in particular, that the incorporation of dopants having 3+ oxidation state leads to higher ionic charge-carrier concentration affecting the overall anion diffusivity, which is essentially determined by cooperative mechanisms involving oxygen interstitials and anions occupying regular apical sites in the layered lattices. However, these dopants tend to decrease anion mobility, both in the rock-salt and perovskite-like layers of the K₂NiF₄-type structure. The likely microscopic mechanisms of anion diffusion in oxygen-hyperstoichiometric La₂Ni(M)O_4+δ are determined.