Innovative processing of dense LSGM electrolytes for IT-SOFC's

Rambabu, B.; Ghosh, Samrat; Zhao, Weichang; Jena, Hrudananda

doi:10.1016/j.jpowsour.2006.04.107

Cited by 58 publications

(35 citation statements)

References 10 publications

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“…In fact, the samples turned from white to black. The same phenomenon is reported in the literature [17,18] for anionic electrolytes based on lanthanum gallate with a perovskite structure. However, from a careful analysis of their diffraction patterns this does not seem to be related to the presence of secondary phases.…”

Section: Preparation Of Substratessupporting

confidence: 87%

Comparison of the electrochemical properties of intermediate temperature solid oxide fuel cells based on protonic and anionic electrolytes

et al. 2008

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The physico-chemical properties of two protonic electrolytes BaCe 0.8 Y 0.2 O 3-d and BaCe 0.9 Y 0.1 O 3-d were investigated. The BaCe 0.8 Y 0.2 O 3-d electrolyte showed better crystallographic purity and lower amount of carbonate phase on the surface. A comparison between the BaCe 0.8 Y 0.2 O 3-d protonic electrolyte supported cell and an anionic (Ce 0.8 Gd 0.2 O 1.95 ) one was made. The maximum power densities (IR-free) of 183 mW cm -2 and 400 mW cm -2 were obtained in H 2 (R.H. 3%) at 700°C, for the protonic and anionic electrolyte based cells, respectively.

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Section: Preparation Of Substratessupporting

confidence: 87%

Comparison of the electrochemical properties of intermediate temperature solid oxide fuel cells based on protonic and anionic electrolytes

et al. 2008

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“…1,9,29,30 Typically, two semicircles representing the grain and grain boundary resistance of the electrolyte material are observed in the Nyquist plot and the conductivity can thus be separately determined for both. At higher temperatures, peak frequencies of the two arcs are increased and exceed the measurement limit of most impedance analyzers (>10 MHz), which then only allows determining the total ionic conductivity.…”

Section: Comparison With Literature Data On Partial Conductivities Ofmentioning

confidence: 99%

“…4,5 However, electrochemical properties of LSGM have been investigated almost exclusively on polycrystalline samples, 1,[6][7][8][9][10][11] in contrast to YSZ where many studies are also available on single crystals. This is largely because of the difficulty to synthesize larger single crystals of the preferred composition La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ with sufficient quality.…”

mentioning

confidence: 99%

Electronic and Ionic Conductivity of La_0.95Sr_0.05Ga_0.95Mg_0.05O_3-δ(LSGM) Single Crystals

Rupp

Głowacki

Fleig

2016

J. Electrochem. Soc.

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The defect chemistry and charge transport properties of La 0.95 Sr 0.05 Ga 0.95 Mg 0.05 O 3-δ (LSGM) single crystals, grown by the Czochralski technique, were studied by impedance spectroscopy performed over a wide temperature range (180-800 • C) and oxygen partial pressures from 0.21 to 1013 mbar. Owing to ion blocking Pt thin film electrodes impedance data showed a Warburg type 45 • slope in the complex impedance plane. The spectra were analyzed by means of a generalized transmission line model which yielded the electronic and ionic conductivity, chemical and dielectric capacitance and the oxygen chemical diffusion coefficient. Activation energies for electronic (0.89 eV) and ionic charge transport (0.95 eV at low and 0.56 eV at high temperatures) were determined. Oxygen partial pressure dependent measurements revealed that the p-type conductivity is exactly proportional to p O 2 1/4 and that the ionic transference number approaches 1 for low oxygen partial pressures and low temperatures. Additional Hebb-Wagner type DC polarization experiments were carried out to determine the n-and p-type conductivities in a broad chemical potential range and to verify the results obtained by the AC impedance measurements. Strontium and magnesium doped lanthanum gallate (LSGM) has been widely investigated as potential electrolyte material in solid oxide fuel cells (SOFC) and thus as promising alternative to the fluorite type electrolytes yttria stabilized zirconia (YSZ) and gadolinium doped ceria (GDC). At lower temperatures (<700• C) the ionic conductivity of LSGM can exceed the conductivity of YSZ by more than a factor of 5 1-3 . Although the ionic conductivity below ca. 600• C is smaller compared to GDC, LSGM has the advantage of a broad electrolytic domain with negligible electronic conductivity under typical reducing and oxidizing conditions of SOFCs.4,5 However, electrochemical properties of LSGM have been investigated almost exclusively on polycrystalline samples, 1,6-11 in contrast to YSZ where many studies are also available on single crystals. This is largely because of the difficulty to synthesize larger single crystals of the preferred composition La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ with sufficient quality. The very few existing studies on LSGM, mostly with lower dopant concentration, dealt with crystal structure, thermal conductivity and ionic conductivity. 7,12 Detailed information on the electronic conductivity of LSGM single crystals is not available so far.Measurements on polycrystalline materials often suffer from difficulties to discriminate between effects induced by grains and grain boundaries. In principle, impedance spectroscopy allows separation of resistive grain and grain boundary contributions and often a brick layer model is used for data analysis. [13][14][15] However, this approach only works at lower temperatures (due to the limited frequency range of impedance spectroscopy) and for the total conductivity, which is largely ionic in LSGM. A separation of resistive bulk and grain boundary contributi...

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“…8 respectively, exceeding values of YSZ material at the same temperatures (0.05 S cm -1 at 800°C) [6]. Therefore, LSGM materials resulted to be potential candidate electrolytes for IT-SOFCs [7,8].…”

Section: Introductionmentioning

confidence: 91%

Influence of Microwave‐Assisted Pechini Method on La_0.80Sr_0.20Ga_0.83Mg_0.17O_3–δ Ionic Conductivity

Boldrini¹,

Mortalò²,

Fasolin³

et al. 2012

Fuel Cells

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With the aim of investigating the microwave influence on the electrolyte material properties, La0.80Sr0.20Ga0.83Mg0.17O2.815 was prepared by both a conventional and a microwave‐assisted sol–gel Pechini method. With respect to the conventional Pechini method (hereafter SGP), the microwave assisted process (hereafter MWA‐SGP) guaranteed a faster procedure, reducing the time needed to remove the excess solvents to complete the polyesterification reaction from some days to a few hours. In fact, when a MWA‐SGP method was used, powders having higher phase purity were obtained. The sintering process at 1,450 °C of the powders prepared by both methods yielded pellets with similar density values (≥92% of theoretical). Nevertheless, only by microwave‐assisted process single‐phase products were obtained and no secondary phases such as tetragonal LaSrGaO4 and LaSrGa3O7 were detected. These by‐products have been demonstrated to be detrimental for conductivity. Indeed, pellets obtained by MWA‐SGP method showed oxygen ionic conductivity values higher (about 30–40%) than those checked for SGP samples, thus demonstrating the important role of the microwave process on reducing time and costs and on improving the electrolyte properties.

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Innovative processing of dense LSGM electrolytes for IT-SOFC's

Cited by 58 publications

References 10 publications

Comparison of the electrochemical properties of intermediate temperature solid oxide fuel cells based on protonic and anionic electrolytes

Comparison of the electrochemical properties of intermediate temperature solid oxide fuel cells based on protonic and anionic electrolytes

Electronic and Ionic Conductivity of La_0.95Sr_0.05Ga_0.95Mg_0.05O_3-δ(LSGM) Single Crystals

Influence of Microwave‐Assisted Pechini Method on La_0.80Sr_0.20Ga_0.83Mg_0.17O_3–δ Ionic Conductivity

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Innovative processing of dense LSGM electrolytes for IT-SOFC's

Cited by 58 publications

References 10 publications

Comparison of the electrochemical properties of intermediate temperature solid oxide fuel cells based on protonic and anionic electrolytes

Comparison of the electrochemical properties of intermediate temperature solid oxide fuel cells based on protonic and anionic electrolytes

Electronic and Ionic Conductivity of La0.95Sr0.05Ga0.95Mg0.05O3-δ(LSGM) Single Crystals

Influence of Microwave‐Assisted Pechini Method on La0.80Sr0.20Ga0.83Mg0.17O3–δ Ionic Conductivity

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Electronic and Ionic Conductivity of La_0.95Sr_0.05Ga_0.95Mg_0.05O_3-δ(LSGM) Single Crystals

Influence of Microwave‐Assisted Pechini Method on La_0.80Sr_0.20Ga_0.83Mg_0.17O_3–δ Ionic Conductivity