Diffusion of Nd and Mo in lanthanum tungsten oxide

Vøllestad, Einar; Teusner, Markus; Souza, Roger A. De; Haugsrud, Reidar

doi:10.1016/j.ssi.2015.03.011

Cited by 5 publications

(5 citation statements)

References 48 publications

(59 reference statements)

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“…Lanthanum tungstates (La 6– x WO 12−δ ) are drawing attention as candidates for hydrogen separation membranes, due to their high ambipolar proton and electronic conductivity and stability in CO 2 and sulfur-containing atmospheres, − unlike the state-of-the-art proton conductors based on BaCeO 3−δ , which exhibit poor stability toward CO 2 due to Ba basicity. − Moreover, lanthanum tungstates display slow cation diffusivities compared to traditional mixed conducting oxides, leading to an enhanced kinetic stability toward demixing or decomposition during operation. , …”

Section: Introductionmentioning

confidence: 99%

“…5−7 Moreover, lanthanum tungstates display slow cation diffusivities compared to traditional mixed conducting oxides, leading to an enhanced kinetic stability toward demixing or decomposition during operation. 8,9 In recent years, lanthanum tungstates have been doped with molybdenum with the goal of increasing the electronic conductivity due to the higher reducibility of molybdenum compared to tungsten. 10−12 Mo-doping improves the hydrogen fluxes compared to the undoped compound, where the best results were obtained by Chen et al 11 for hollow-fiber membranes of La 5.6 W 0.6 Mo 0.4 O 11.4 .…”

Section: Introductionmentioning

confidence: 99%

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Metal-Doping of La_5.4MoO_11.1 Proton Conductors: Impact on the Structure and Electrical Properties

et al. 2018

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La5.4MoO11.1 proton conductors with different metal doping (Ca2+, Sr2+, Ba2+, Ti4+, Zr4+, and Nb5+ ) have been prepared and structurally and electrically characterized. Different polymorphs are stabilized depending on the doping and cooling rate used during the synthesis process. The most interesting results are obtained for Nb-doping, La5.4Mo1–x Nb x O11.1–x/2, where single compounds are obtained in the compositional range 0 ≤ x ≤ 0.2. These materials are fully characterized by structural techniques such as X-ray and neutron powder diffraction and transmission electron microscopy, which independently confirm the changes of polymorphism. Scanning electron microscopy and impedance spectroscopy measurements in dry/wet gases (N2, O2, and 5% H2–Ar) showed an enhancement of the sinterability and electrical properties of the materials after Nb-doping. Conductivity measurements under very reducing conditions revealed that these materials are mixed ionic-electronic conductors, making them potential candidates for hydrogen separation membranes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Metal-Doping of La_5.4MoO_11.1 Proton Conductors: Impact on the Structure and Electrical Properties

et al. 2018

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“…It is considered to be the next-generation ceramic membrane material with high hydrogen permeability. First, Mo-doping can effectively improve the electronic conductivity of hydrogen permeation membranes or oxygen permeation membranes [59,60]. Mo doping is expected to be the most effective doping strategy to improve the electronic conductivity of LaWO.…”

Section: Current Status Of Hydrogen Permeation Membrane 41 Single-pha...mentioning

confidence: 99%

Rare Earth Tungstate: One Competitive Proton Conducting Material Used for Hydrogen Separation: A Review

Cheng

2023

Separations

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Membrane technology is an advanced hydrogen separation method that is of great significance in achieving hydrogen economy. Rare earth tungstate membranes have both high hydrogen permeability and remarkable mechanical/chemical stability, exhibiting good application prospects in hydrogen separation. This review provides the basic aspects and research progress on rare earth tungstate hydrogen separation membranes. The crystal structure, proton transport properties, and membrane stability under a chemical atmosphere are introduced. Different membrane construction designs, such as single-phase, dual-phase, and asymmetric rare earth tungstate membranes, are summarized. Lastly, the existing problems and development suggestions for tungstate membranes are discussed.

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“…Under wet sweep conditions there is, in principle, no gradient in the water vapor pressure across the membrane. For a mixed oxide ion-proton-electron conductor, these gradients in the chemical potential of hydrogen and oxygen enforce hydrogen transport from the feed side to the sweep side and oxygen transport from the permeate side to the feed side (and notably also cation diffusion from reducing toward oxidizing atmospheres 26 ). Electronic charge carriers will in both cases take part in balancing the charge transport of ions, all together resulting in a net transport of hydrogen and oxygen gas.…”

Section: Correlation Of Conductivity and Flux Datamentioning

confidence: 99%

Enhancement of the Electron Conductivity ofLa₂₇(W_0.85Nb_0.15)₅O_{55.5 − δ}by Mo Doping for Hydrogen Permeation

Cao

Xiong

et al. 2016

J. Electrochem. Soc.

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Lanthanum tungstates are a family of promising proton conductors for potential applications in fuel cells and in hydrogen permeation membranes. Single phase 15% and 30% Mo-doped La 27 (W 0.85 Nb 0.15 ) 5 O 55.5−δ were synthesized via a solid-state reaction route. The cell parameters of the cubic unit cell with space group F-43m increased from 11.181(7) Å to 11.186(5) Å when increasing the Mo content from 0% to 30%. The proton concentration in La 27 (W 0.55 Nb 0.15 Mo 0.30 ) 5 O 55.5−δ was similar to La 27 (W 0.85 Nb 0.15 ) 5 O 55.5−δ , and the influence of Mo doping on the total, proton and electron conductivity of La 27 (W 0.85 Nb 0.15 ) 5 O 55.5−δ was small in wet O 2 . The electron conductivity of 30% Mo-doped La 27 (W 0.85 Nb 0.15 ) 5 O 55.5−δ in wet 5% H 2 -Ar increased by more than one order of magnitude compared to the undoped material. The hydrogen flux increased from 4.96 × 10 −5 to 5.82 × 10 −4 ml cm −1 min −1 by 30% Mo doping of La 27 (W 0.85 Nb 0.15 ) 5 O 55.5−δ with dry Ar as the sweep gas and wet H 2 as the feed gas at 750 • C.

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Diffusion of Nd and Mo in lanthanum tungsten oxide

Cited by 5 publications

References 48 publications

Metal-Doping of La_5.4MoO_11.1 Proton Conductors: Impact on the Structure and Electrical Properties

Metal-Doping of La_5.4MoO_11.1 Proton Conductors: Impact on the Structure and Electrical Properties

Rare Earth Tungstate: One Competitive Proton Conducting Material Used for Hydrogen Separation: A Review

Enhancement of the Electron Conductivity ofLa₂₇(W_0.85Nb_0.15)₅O_{55.5 − δ}by Mo Doping for Hydrogen Permeation

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Diffusion of Nd and Mo in lanthanum tungsten oxide

Cited by 5 publications

References 48 publications

Metal-Doping of La5.4MoO11.1 Proton Conductors: Impact on the Structure and Electrical Properties

Metal-Doping of La5.4MoO11.1 Proton Conductors: Impact on the Structure and Electrical Properties

Rare Earth Tungstate: One Competitive Proton Conducting Material Used for Hydrogen Separation: A Review

Enhancement of the Electron Conductivity ofLa27(W0.85Nb0.15)5O55.5 − δby Mo Doping for Hydrogen Permeation

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Metal-Doping of La_5.4MoO_11.1 Proton Conductors: Impact on the Structure and Electrical Properties

Metal-Doping of La_5.4MoO_11.1 Proton Conductors: Impact on the Structure and Electrical Properties

Enhancement of the Electron Conductivity ofLa₂₇(W_0.85Nb_0.15)₅O_{55.5 − δ}by Mo Doping for Hydrogen Permeation