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S. N. Shkerin D. I. Bronin S. A. Kovyazina V. P. Gorelov A. V. Kuz'min Z. S. Martem'yanova S. M. Beresnev 《Journal of Structural Chemistry》2003,44(2):216-221
Electric conductivity, Raman spectra, and thermal expansion of La0.88Sr0.12Ga0.82Mg0.18O2.85 solid solution (LSGM1218) based on lanthanum gallate were studied at various temperatures, and Xray phase analysis was performed at room temperature. Dilatometric measurements showed that secondorder phase transitions occur at 775±10$ and 880± 20 K. The transition around 880 K is confirmed by Raman spectra and by a change in the conductivity activation energy in this temperature range. This transition is associated with a symmetry change in the oxygen sublattice. 相似文献
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Francesco Bozza Riccardo Polini Enrico Traversa 《Electrochemistry communications》2009,11(8):1680-1683
Remarkable power density was obtained for anode-supported solid oxide fuel cells (SOFCs) based on La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM) electrolyte films, fabricated following an original procedure that allowed avoiding undesired reactions between LSGM and electrode materials, especially Ni. Electrophoretic deposition (EPD) was used for the fabrication of 30 μm-thick electrolyte films. Anode supports were made of La0.4Ce0.6O2−x (LDC). The LSGM powder was deposited by EPD on an LDC green tape-cast membrane added with carbon powder, both as pore former and substrate conductivity booster. A subsequent co-firing step at 1490 °C produced dense electrolyte films on porous LDC skeletons. Then, a La0.8Sr0.2Fe0.8Co0.2O3−δ (LSFC) cathode was applied by slurry-coating and calcined at 1100 °C. Finally, the porous LDC layer was impregnated with molten Ni nitrate to obtain, after calcination at 900 °C, a composite NiO–LDC anode. Maximum power densities of 780, 450, 275, 175, and 100 mW/cm2 at 700, 650, 600, 550, and 500 °C, respectively, were obtained using H2 as fuel and air as oxidant, demonstrating the success of the processing strategy. As a comparison, electrolyte-supported SOFCs made of the same materials were tested, showing a maximum power density of 150 mW/cm2 at 700 °C, more than 5 times smaller than the anode-supported counterpart. 相似文献
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The use of Sr-Mg-doped LaGaO3 (LSGM), a highly conducting oxygen ion electrolyte, in intermediate temperature solid oxide fuel cells (IT-SOFC) technology
requires suitable electrode materials. Because the Sr-doped LaMnO3 (LSM) cathode coupled with the YSZ electrolyte had shown relatively good performances, it has been also suggested for LSGM-based
cells. As cathode overpotential is the main performance limitation, the optimization of the LSM/LSGM interface might be of
fundamental relevance in the technology development of LSGM-based IT-SOFC. LSM films with different porosities were screen
printed on both faces of the LSGM pellets; their morphology and electrical properties were investigated by scanning electron
microscopy and impedance spectroscopy, respectively. Porosity was induced by the addition of icing sugar (3–5 wt%) to the
LSM powder during ink preparation. Homogeneous electrode layers with a thickness of about 30 μm were obtained. The higher
the sugar amount, the higher the film porosity and the lower the LSM grain size. The Nyquist plots show two low frequency
arcs to which the charge transfer and mass transfer process or oxygen dissociation process were associated, respectively.
One can expect that the best electrochemical performances are obtained using highly porous electrode.
Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007. 相似文献
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In this study, the A-site-deficient ABO3 perovskites La0.9–x
Sr0.1Ga0.8Mg0.2O3– with x=0.025, 0.05, 0.075, 0.1, and 0.2 were prepared by conventional solid state reactions. X-ray investigations were carried out in order to determine the influence of the A-site deficiencies on the structure. The electrical conductivities were measured as a function of both temperature and oxygen partial pressure in ranges 500–1000 °C and 0.2–10–6 atm, respectively. Only for small x values were single phases obtained. All compositions with A-site deficiencies exhibit a lower conductivity compared to the stoichiometric compound. It is shown by SEM micrographs that the sample morphology is changed by an A-site-deficient preparation as well. For A-site-deficient compositions, a reduction of the grain size is observed, most likely due to impurity inclusions in the grain boundaries. 相似文献
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The deposition of gadolinia-doped ceria (CGO, Gd0.1Ce0.9O1.95) and LaGaO3-based perovskite oxides (LSGM, La0.9Sr0.1Ga0.8Mg0.2O2.87) thin films on a stainless steel substrate was studied using the electrostatic spray deposition (EDS) technique. The effect of process conditions, such as deposition temperature, deposition time and liquid flow rate, on the surface morphology and microstructure of thin films was examined with scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The deposited CGO films with a highly porous and three-dimensional interconnected structure were obtained at a liquid flow rate of 0.5 ml/h, a deposition temperature of 503 K and a deposition time ranging from 0.5 to 1 h. On the other hand, the deposited LSGM thin films with porous microstructure were also obtained at the deposition time of 1 h, the deposition temperature of 533 K and the liquid flow rate of 0.5 ml/h. The deposited CGO and LSGM thin films were amorphous at the used deposition temperature. Subsequently, the samples were annealed at 1173 K for 2 h and the desired crystal structures were obtained. The chemical analysis of the thin films was investigated by energy dispersive X-ray (EDX) analysis. The observed chemical compositions of the samples were in a fair agreement with those of the starting solutions. 相似文献
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A dense La0.8Sr0.2Ga0.83Mg0.17O2.815 electrolyte in pure perovskite phase was prepared by a polyacrylic acid assisted solid state reaction method, and the effects of La source on the structure and electrochemical performance were also studied. By means of XRD and SEM, the structure of this material was characterized, and the electrochemical properties were studied through AC impedance diagram. The results show that the sample presents a single perovskite-type phase after sintering at 1 450 ℃ and the relative density is 94%. The specimen has the lower activate energy and higher electrical conductivity at 600 ℃. There are two different activation energy at the turning point of 650 ℃, which are 74.6 and 42.4 kJ·mol-1, respectively. The electrical conductivity is 0.057 S·cm-1 and 0.017 S·cm-1 at the temperature of 800 ℃ and 600 ℃, respectively. 相似文献
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