Interstitial Oxide Ion Order and Conductivity in La1.64Ca0.36Ga3O7.32 Melilite

Li, Man-Rong; Kuang, Xiaojun; Chong, Samantha Y.; Xu, Zhou; Thomas, Christopher I.; Niu, Hongjun; Claridge, John B.; Rosseinsky, Matthew J.

doi:10.1002/anie.200906220

Cited by 45 publications

(102 citation statements)

References 17 publications

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“…In low-dimensional structures, the ease of deformation and rotation of tetrahedral units allows for the accommodation and transportation of the interstitial defects. For example, La 10− x ( M O 4 ) 6 O 3−1.5 x ( M = Si, Ge)-based apatites 8,10 and La 2 Mo 2 O 9 -based (LaMOX) 2,6 oxide ion conductors adopt isolated tetrahedral anion structures, and Ln 1+ x A 1− x Ga 3 O 7+0.5 x ( Ln = La, Gd, Eu, Tb, A = Ca, Sr, Ba) gallate melilites exhibit a two-dimensional (2D) interstitial oxide ion conductivity in the layered tetrahedral network 1,11–15 .…”

Section: Introductionmentioning

confidence: 99%

Cooperative mechanisms of oxygen vacancy stabilization and migration in the isolated tetrahedral anion Scheelite structure

Yang¹,

Fernández-Carrión

Wang³

et al. 2018

Nat Commun

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140

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Tetrahedral units can transport oxide anions via interstitial or vacancy defects owing to their great deformation and rotation flexibility. Compared with interstitial defects, vacancy-mediated oxide-ion conduction in tetrahedra-based structures is more difficult and occurs rarely. The isolated tetrahedral anion Scheelite structure has showed the advantage of conducting oxygen interstitials but oxygen vacancies can hardly be introduced into Scheelite to promote the oxide ion migration. Here we demonstrate that oxygen vacancies can be stabilized in the BiVO4 Scheelite structure through Sr2+ for Bi3+ substitution, leading to corner-sharing V2O7 tetrahedral dimers, and migrate via a cooperative mechanism involving V2O7-dimer breaking and reforming assisted by synergic rotation and deformation of neighboring VO4 tetrahedra. This finding reveals the ability of Scheelite structure to transport oxide ion through vacancies or interstitials, emphasizing the possibility to develop oxide-ion conductors with parallel vacancy and interstitial doping strategies within the same tetrahedra-based structure type.

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Section: Introductionmentioning

confidence: 99%

Cooperative mechanisms of oxygen vacancy stabilization and migration in the isolated tetrahedral anion Scheelite structure

Yang¹,

Fernández-Carrión

Wang³

et al. 2018

Nat Commun

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140

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“…Although the occurrence of interstitial oxide ion conductors is relatively rare, high mobility of oxygen interstitial defects has been observed in apatite‐type silicates and germinates, and in the recently discovered melilite‐type gallates . Differing from the isolated tetrahedron with more deformation and rotation flexibility in apatite structure, the A 3+ B 2+ Ga 3 O 7 ‐based gallate melilites form an important new family of interstitial oxide ion conductors based on the more commonly linked polyhedral structure of layered tetrahedral network . They consist of alternating 8‐coordinate large A/B cationic layers and (3,4)‐linked GaO 4 tetrahedral layers.…”

Section: Introductionmentioning

confidence: 99%

Chemical Bonding Effect on the Incorporation and Conduction of Interstitial Oxide Ions in Gallate Melilites

Zhou

et al. 2019

Advcd Theory and Sims

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The ability to incorporate high content of interstitial oxygen ions (O i ) in La 1+x Sr 1-x Ga 3 O 7+0.5x melilite owing to the good size match between La 3+ and Sr 2+ ions is well documented. Here, the complete substitution of Sr 2+ by Pb 2+ lone-pair cations results in a significant loss of this ability, even though Sr 2+ and Pb 2+ have almost the same effective ionic radius. To explore the fundamental mechanism underlying this result, density functional theory (DFT) calculations are performed on both the LaSrGa 3 O 7 -based and LaPbGa 3 O 7 -based materials, revealing a new chemical bonding effect on the incorporation of mobile oxygen interstitial defects in melilites. For LaSrGa 3 O 7 -based melilites, the interstitial oxygens have cooperatively weak antibonding interactions with the framework oxygen atoms (O f ). This antibonding O i -O f interaction pushes O i toward a 3-linked Ga ion, enhancing the covalent bonding between this Ga ion and O i . In addition, the antibonding O i -O f interaction makes the oxygen interstitial defects and framework atoms highly active, benefiting the migration of defects. In contrast, forLaPbGa 3 O 7 -based materials, the 6s 2 electrons of Pb 2+ point toward the c-axis and form antibonding with framework O 2− . This antibonding projects into the tunnel void, thereby directly hindering the entrance of interstitial oxygen atoms into the pentagonal rings.

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“…In La 1 + x Sr 1-x Ga 3 O 7 + 0.5x and La 1 + x Ca 1-x Ga 3 O 7 + 0.5x solid solutions, the increase of the interstitial oxide ion content can lead to the ordering of interstitial oxide ions among the pentagonal rings, which reduces the symmetry from tetragonal (T) to (pseudo) orthorhombic (O) and therefore the associated conductivity. [20,33] At room temperature (RT), the T polymorph in La 1 + x Ca 1-x Ga 3 O 7 + 0.5x can extend up to x = 0.55, above which the O polymorph forms until x = 0.64 (Figure 8a), which transform to the T phase above 600°C (Figure 8b). Similarly, for La 1 + x Sr 1-x Ga 3 O 7 + 0.5x at RT, the T phase extends up to x = 0.6 and the O phase form for 0.6 < x � 0.64, which evolves to the T phase above 565°C.…”

Section: Interstitial Oxide Ion Orderingmentioning

confidence: 99%

Section: Interstitial Oxide Ion Orderingmentioning

confidence: 99%

Development of Melilite‐Type Oxide Ion Conductors

Zhou

Allix

et al. 2020

The Chemical Record

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Lowering the operating temperature of solid oxide fuel cells (SOFCs) requires high performance oxide ion conductor electrolytes. Recently tetrahedra-based structures have been attracting considerable attention for oxide ion conductor development, among which the layered tetrahedral network melilite structure appears particularly interesting owing to its remarkable capability to accommodate and transport interstitial oxide ions, compared with isolated tetrahedral anion structures. Stabilization and migration mechanisms of interstitial oxide ions in melilites have been systematically investigated using local structural relaxation from both electrostatic Coulomb interaction and chemical bonding aspects based on atomic and electronic structures respectively using experimental and theoretical approaches. These reveal cationic size and chemical bonding effects on stabilization and migration mechanisms of interstitial oxide ions. Lately, full crystallization from glass, an innovative synthesis method, was employed to produce new metastable melilite oxide ion conductors which are inaccessible using classic solid state reaction owing to cationic size effect. Finally, the thermal and chemical stability at low temperature and the high oxide ion conductivity of the best melilite oxide ion conductors based on LaSrGa 3 O 7 are likely to provide real possibilities of applications of melilite-type electrolytes in SOFCs and other related devices.

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Interstitial Oxide Ion Order and Conductivity in La_1.64Ca_0.36Ga₃O_7.32 Melilite

Cited by 45 publications

References 17 publications

Cooperative mechanisms of oxygen vacancy stabilization and migration in the isolated tetrahedral anion Scheelite structure

Cooperative mechanisms of oxygen vacancy stabilization and migration in the isolated tetrahedral anion Scheelite structure

Chemical Bonding Effect on the Incorporation and Conduction of Interstitial Oxide Ions in Gallate Melilites

Development of Melilite‐Type Oxide Ion Conductors

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