Complete structural model for lanthanum tungstate: a chemically stable high temperature proton conductor by means of intrinsic defects

Magrasó, Anna; Polfus, Jonathan M.; Frontera, C.; Canales‐Vázquez, Jesús; Kalland, Liv-Elisif; Hervoches, Charles H.; Erdal, Skjalg; Hancke, Ragnhild; Islam, M. Saïful; Norby, Truls; Haugsrud, Reidar

doi:10.1039/c2jm14981h

Cited by 102 publications

(160 citation statements)

References 11 publications

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“…Recently, Magrasó et al [2] showed that "La 6 WO 12 " was best described as La 28-x W 4+x O 54+3x/2 (x ∼ 0.85) (called hereafter LWO) where tungsten dissolves in lanthanum sites. The symmetry of the space group is tetragonal and the cell parameters are a ∼ c/√2 Å, c ∼ 11.19 Å.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Lanthanum Tungstate/Pr₂NiO₄ Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

2012

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La6WO12, recently reformulated La28–xW4+xO54+3x/2 exhibits a good level of protonic conductivity and chemical stability toward acidic gases. It is therefore a potential material for use as electrolyte in proton conducting solid oxide fuel cells (PC‐SOFC). Pr2NiO4 is a cathode material tested for SOFC in which proton conductivity has been demonstrated recently. In this study, compatibility between lanthanum tungstate and praseodymium nickelate has been investigated by powder X‐ray diffraction (XRD). Microstructure of symmetrical cells based on the lanthanum tungstate and Pr2NiO4 has been analyzed by scanning electron microscopy (SEM) and performance of the cathode has been evaluated by electrochemical impedance spectroscopy (EIS) through the value of the area specific resistance (ASR). To optimize the ASR value, different parameters were modified such as the Pr2NiO4 calcination temperature, the firing temperature of the symmetrical cells, the thickness of the Pr2NiO4 layer, and the composition of the composite cathode. An ASR value of 0.46 Ω cm2 at 700 °C has been obtained showing that lanthanum tungstate electrolyte associated with Pr2NiO4 cathode is a promising half cell for application in PC‐SOFC.

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Section: Introductionmentioning

confidence: 99%

Optimization of the Lanthanum Tungstate/Pr₂NiO₄ Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

2012

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“…[23][24][25] Escolástico et al 26 found that the H 2 permeation flux through a La 5.5 WO 11.25-δ membrane only changed slightly over 72 h when using a mixture of 15% CO 2 in Ar as a sweep gas at 800°C.…”

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confidence: 99%

A CO₂‐stable hollow‐fiber membrane with high hydrogen permeation flux

Chen

Liao

et al. 2015

AIChE Journal

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A Mo-substituted lanthanum tungstate mixed proton-electron conductor, La 5.5 W 0.6 Mo 0.4 O 11.25-δ (LWM04), was synthesized using solid state reactions. Dense U-shaped LWM04 hollow-fiber membranes were successfully prepared using wet-spinning phase-inversion and sintering. The stability of LWM04 in a CO 2 -containing atmosphere and the permeation of hydrogen through the LWM04 hollow-fiber membrane were investigated in detail. A high hydrogen permeation flux of 1.36 ml/min·cm 2 was obtained for the U-shaped LWM04 hollow-fiber membranes at 975°C when a mixture of 80% H 2 -20% He was used as the feed gas and the sweep side was humidified. Moreover, the hydrogen permeation flux did not significantly decrease over 70 h of operation when fed with a mixture containing 25% CO 2 , 50%H 2 , and 25% He, indicating that the LWM04 hollow-fiber membrane has good stability under a CO 2 -containing atmosphere.

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“…m is molar density, 4 -3x represents the concentration of oxygen vacancies in the dry state [15], given by the W-excess, x, and µ 0 is the pre-exponential mobility factor for each charge carrier. If we plot ln(σ v T) vs 1/T in the range 450-900 ⁰C and use pre-defined enthalpies for each charge carrier mobility [16] as well as a general concentration expression for protons [17] containing standard hydration entropy and enthalpy [18], pre-exponential mobility factors for each partial conductivity in the electrolyte can be extracted through equations 4 and 5.…”

Section: Theorymentioning

confidence: 99%

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

Strandbakke

Dyrlie

Hage

et al. 2016

J. Electrochem. Soc.

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Composite electrodes of La 0.8 Sr 0.2 MnO 3 (LSM) / La 28-x W 4+x O 54+3x/2 (x=0.85, "LWO56") on LWO56 electrolytes have been characterized by use of electrochemical impedance spectroscopy vs pO 2 and temperature from 900 ⁰C, where LWO56 is mainly oxide ion conducting, to 450 ⁰C, where it is proton conducting in wet atmospheres. The impedance data are analyzed in a model which takes into account the simultaneous flow of oxide ions and protons across electrolyte and electrodes, allowing extraction of activation energies and pre-exponential factors for the partial electrode reactions of protons and oxide ions. One composite electrode was infiltrated with Pt nanoparticles with average diameter of 5 nm, lowering the overall electrode polarization resistance (R p ) at 650 ⁰C from 260 to 40 Ω cm 2 . The Pt-infiltrated electrode appears to be rate limited by surface reactions with activation energy of ~90 kJ mol -1 in the low temperature proton 2 transport regime and ~150 kJ mol -1 in the high temperature oxide ion transport regime. The charge transfer reaction, which makes a minor contribution to R p , exhibits activation energies of ~85 kJ mol -1 for both oxide ion and proton charge transfer.

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Complete structural model for lanthanum tungstate: a chemically stable high temperature proton conductor by means of intrinsic defects

Cited by 102 publications

References 11 publications

Optimization of the Lanthanum Tungstate/Pr₂NiO₄ Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

Optimization of the Lanthanum Tungstate/Pr₂NiO₄ Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

A CO₂‐stable hollow‐fiber membrane with high hydrogen permeation flux

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

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Complete structural model for lanthanum tungstate: a chemically stable high temperature proton conductor by means of intrinsic defects

Cited by 102 publications

References 11 publications

Optimization of the Lanthanum Tungstate/Pr2NiO4 Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

Optimization of the Lanthanum Tungstate/Pr2NiO4 Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

A CO2‐stable hollow‐fiber membrane with high hydrogen permeation flux

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

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Product

Resources

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Optimization of the Lanthanum Tungstate/Pr₂NiO₄ Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

Optimization of the Lanthanum Tungstate/Pr₂NiO₄ Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

A CO₂‐stable hollow‐fiber membrane with high hydrogen permeation flux