Adaptation of an electrochemical system for measurement and regulation of oxygen partial pressure to a symmetrical thermogravimetric analysis system developed using a Cahn 1000 electrobalance

Caneiro, A.; Bavdaz, P.; Fouletier, Jacques; Abriata, J. P.

doi:10.1063/1.1137090

Cited by 84 publications

(51 citation statements)

References 13 publications

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“…A highly sensitive thermogravimetric equipment consisting of a symmetrical thermobalance based on a Cahn 1000 electrobalance coupled to a ZrO 2 -based oxygen pump and sensor system 36 was used, which allows determination of sample mass changes within ±10 μg with 0.6 g of STF37 powder. The oxygen partial pressure (pO 2 ) was varied between 10 −25 and 1 bar by using O 2 -Ar and H 2 -H 2 O mixtures.…”

Section: Methodsmentioning

confidence: 99%

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

Nenning

Volgger

Miller

et al. 2017

J. Electrochem. Soc.

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Reduction-stable mixed ionic and electronic conductors such as Sr(Ti,Fe)O 3-δ (STF) are promising materials for application in anodes of solid oxide fuel cells. The defect chemistry of STF and its properties as solid oxide fuel cell (SOFC) cathode have been studied thoroughly, while mechanistic investigations of its electrochemical properties as SOFC anode material are still scarce. In this study, thin film model electrodes of STF with 30% and 70% Fe content were investigated in H 2 +H 2 O atmosphere by electrochemical impedance spectroscopy. Lithographically patterned thin film Pt current collectors were applied on top or beneath the STF thin films to compensate for the low electronic conductivity under reducing conditions. Oxygen exchange resistances, electronic and ionic conductivities and chemical capacitances were quantified and discussed in a defect chemical model. Increasing Fe content increases the electro-catalytic activity of the STF surface as well as the electronic and ionic conductivity. Current collectors on top also increase the electrochemical activity due to a highly active Pt-atmosphere-STF triple phase boundary. Furthermore, the electrochemical activity depends decisively on the H 2 :H 2 O mixing ratio and the polarization. Acceptor-doped mixed ionic and electronic conductors are a promising class of materials for application in solid oxide fuel cell (SOFC) electrodes and they are widely investigated as SOFC cathodes due to their low polarization resistance.1-3 Some of these materials are chemically stable and mixed conducting also in humidified hydrogen atmosphere, 4 which makes them applicable in SOFC anodes. Several mixed conductors, such as acceptor doped (La,Sr)(Cr,Mn)O 3 , [5][6][7][8] donor-doped SrTiO 3 9,10 and Sr(Ti,Fe)O 3-δ -Ce 0.9 Gd 0.1 O 2-δ (STF-GDC) composites 11 were investigated in form of porous SOFC anodes. Most of these studies revealed moderately low polarization resistances. In STF-GDC composites, for example, the anode polarization resistance was <0.2 cm 2 at 800• C, and the overall performance increased with increasing Fe content. However, the usually ill-defined geometry of porous electrodes makes the analysis of specific materials parameters such as electronic and ionic conductivity or oxygen exchange activity very challenging.Thin film model electrodes have well defined and controllable geometry and comparatively simple pathways of electron and oxygen ion migration. This strongly facilitates identification of reaction pathways and quantification of the oxygen exchange activity of the material's surface. [12][13][14][15][16][17][18] Mechanistic studies using thin film model electrodes have so far been performed mainly in oxidizing atmosphere. Thorough studies of the mechanisms of electrochemical oxygen exchange in reducing atmospheres are still largely missing, not only for STF, but for most reduction stable mixed conductors, except for (Gd or Sm) doped ceria [19][20][21][22][23][24] and a study on (La,Sr)FeO 3-δ. 25 The typically low electronic conductivity of accep...

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Section: Methodsmentioning

confidence: 99%

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

Nenning

Volgger

Miller

et al. 2017

J. Electrochem. Soc.

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“…The pO 2 was controlled and sensed using an electrochemical gas blending system consisting of a zirconia pump and oxygen sensor 39 coupled to the impedance test system. The EIS spectra were fit using an electrical equivalent circuit with an inductor (L) in series with a resistor (R el ) and a Gerischer-type element (Z G ) applying a MatLab code.…”

Section: Methodsmentioning

confidence: 99%

Determination of Electrode Oxygen Transport Kinetics Using Electrochemical Impedance Spectroscopy Combined with Three-Dimensional Microstructure Measurement: Application to Nd₂NiO_4+δ

Yakal-Kremski

Mogni

Montenegro-Hernández

et al. 2014

J. Electrochem. Soc.

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Oxygen reduction kinetic parameters -oxygen ion diffusion D δ , molar surface exchange rate O and surface exchange coefficient k -were determined for porous Nd 2 NiO 4+δ solid oxide fuel cell cathodes as a function of temperature and oxygen partial pressure by analyzing electrochemical impedance spectroscopy data using the Adler-Lane-Steele model. Electrode microstructural data used in the model calculations were obtained by three-dimensional focused ion beam-scanning electron microscope tomography. Cathodes were fabricated using Nd 2 NiO 4+δ powder derived from a sol-gel method and were tested as symmetrical cells with LSGM electrolytes. The oxygen surface exchange rate exhibited a power-law dependency with oxygen partial pressure, whereas the oxygen diffusivity values obtained varied only slightly. The present analysis suggests that the O-interstitial diffusion has a bulk transport path, whereas the surface exchange process involves dissociative adsorption on surface sites followed by O-incorporation. For Nd 2 NiO 4+δ at 700 • C and 0.2 atm oxygen pressure, D δ = 5.6 · 10 −8 cm 2 s −1 , O = 2.5 · 10 −8 mol · cm −2 s −1 . The present D δ and O values and their activation energies are slightly different to those previously reported for Nd 2 NiO 4+δ using other measurement methodologies, and lower than typical state-of-the-art Co-rich perovskites. However, the average k δ = 1.0 10 −5 cm · s −1 at 700 • C is comparable to those of fast oxygen exchange rate perovskites.

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“…Equilibrium Po2 measurements were performed with thermogravimetric equipment consisting of a symmetrical thermobalance based on a Cahn 1000 electrobalance coupled to an electrochemical system for the measurement and control of P%, specially designed for this kind of study [22]. The electrochemical system (zirconla pump and oxygen sensor) [23] provides a controlled Ar-O2 atmosphere for the thermobalance, with Poe ranging from 1.01xl02 to 10 -4 kPa.…”

Section: Methodsmentioning

confidence: 99%

Oxygen non-stoichiometry of Nd1.85Ce0.15Cu1+δOy as a function of δ and its relation with the superconducting properties

Prado

Caneiro

Serquis

1997

Journal of Thermal Analysis

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Thermogravimetric measurements of the equilibrium oxygen partial pressure (Po) as a function of the oxygen content y were performed on Ndl.ssCe0.15Cul,~Oy samples with cdntrolled Cu contents (1 +6= 1.00, 1.01 and 1.02) at 1173 and 1237 K. The data obtained showed a dependence of the oxygen non-stoichiometry on the nominal Cu content. These measurements are discussed in terms of the presence of Cu defects in the T' structure. The superconducting response of this material in samples with controlled oxygen and Cu contents was also studied. The superconducting response was found to be very sensitive to the presence of small amounts of cationic and anionic defects.

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Adaptation of an electrochemical system for measurement and regulation of oxygen partial pressure to a symmetrical thermogravimetric analysis system developed using a Cahn 1000 electrobalance

Cited by 84 publications

References 13 publications

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

Determination of Electrode Oxygen Transport Kinetics Using Electrochemical Impedance Spectroscopy Combined with Three-Dimensional Microstructure Measurement: Application to Nd₂NiO_4+δ

Oxygen non-stoichiometry of Nd1.85Ce0.15Cu1+δOy as a function of δ and its relation with the superconducting properties

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Adaptation of an electrochemical system for measurement and regulation of oxygen partial pressure to a symmetrical thermogravimetric analysis system developed using a Cahn 1000 electrobalance

Cited by 84 publications

References 13 publications

The Electrochemical Properties of Sr(Ti,Fe)O3-δfor Anodes in Solid Oxide Fuel Cells

The Electrochemical Properties of Sr(Ti,Fe)O3-δfor Anodes in Solid Oxide Fuel Cells

Determination of Electrode Oxygen Transport Kinetics Using Electrochemical Impedance Spectroscopy Combined with Three-Dimensional Microstructure Measurement: Application to Nd2NiO4+δ

Oxygen non-stoichiometry of Nd1.85Ce0.15Cu1+δOy as a function of δ and its relation with the superconducting properties

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The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

Determination of Electrode Oxygen Transport Kinetics Using Electrochemical Impedance Spectroscopy Combined with Three-Dimensional Microstructure Measurement: Application to Nd₂NiO_4+δ