Pulsed laser deposition of conducting porous La-Sr-Co-O films

Chen, X.; Wu, N. J.; Ritums, D.; Ignatiev, A.

doi:10.1016/s0040-6090(98)01347-9

Cited by 55 publications

(43 citation statements)

References 7 publications

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“…Nevertheless, as lower temperature processing techniques such as thin film deposition for the cathode fabrication became available, Co-containing cathodes fabricated by such processing have been widely studied to investigate their material compatibility with the zirconia base electrolyte at lower processing and operating temperatures than those of conventional SOFCs [3,7,[9][10][11][12][13][14][15]. It is generally known that the reaction between the Co-containing cathode and yttria stabi- …”

Section: Introductionmentioning

confidence: 99%

“…Thus, there have been many efforts to apply Co-containing cathode materials directly over YSZ with thin film deposition techniques which can prevent the cathode/electrolyte combination from being exposed to high temperatures [9][10][11][12][13][14][15]. Especially in the field of the micro-SOFC research with thin film components, cells have been fabricated by directly applying Co-containing cathodes to the YSZ electrolyte because it is expected that the interfacial reaction would not occur at low temperatures [4,16,17].…”

Section: Introductionmentioning

confidence: 99%

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Direct Applicability of La_0.6Sr_0.4CoO_3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

et al. 2010

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For investigating the direct applicability of highly active cobalt containing cathodes on YSZ electrolytes at a lower processing and operating temperature range (T ≤ 650 °C), we fabricated a thin film lanthanum strontium cobalt oxide (LSC) cathode on an yttria stabilised zirconia (YSZ)‐based solid oxide fuel cell (SOFC) via pulsed laser deposition (PLD). Its electrochemical performance (5.9 mW cm–2 at 0.7 V, 650 °C) was significantly inferior to that (595 mW cm–2 at 0.7 V, 650 °C) of an SOFC with a thin (t ∼ 200 nm) gadolinium doped ceria (GDC) buffer layer in between the LSC thin film cathode and the YSZ electrolyte. It implies that even though the cathode processing and cell operating temperatures were strictly controlled not to exceed 650 °C, the direct application of LSC on YSZ should be avoided. The origin of the cell performance deterioration is thoroughly studied by glancing angle X‐ray diffraction (GAXRD) and transmission electron microscopy (TEM), and the decomposition of the cathode and diffusion of La and Sr into YSZ were observed when LSC directly contacted YSZ.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct Applicability of La_0.6Sr_0.4CoO_3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

et al. 2010

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“…Apart from the conventional methods of cathode preparation, including high temperature calcination, mechanical grinding of powders, screen printing and sintering of thick fi lm layers, alternative synthesis and deposition routes are available. Nanocrystalline LSC or La 1−x Sr x Co 1−y Fe y O 3− δ thin fi lms on electrolyte substrates were already fabricated by pulsed laser deposition, [6][7][8][9] DC, and RF sputtering, [ 10,11 ] spray pyrolysis, [ 12 ] and sol-gel deposition. [13][14][15][16][17] In this work the chemical and structural properties and the stability of nanoscaled La 0.6 Sr 0.4 CoO 3− δ LSC thin fi lm cathodes on polycrystalline Gd 0.1 Ce 0.9 O 1.95 (CGO) substrates were investigated thoroughly.…”

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confidence: 99%

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Dieterle

Bockstaller

Gerthsen

et al. 2011

Advanced Energy Materials

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Numerous preparation techniques for perovskite-based MIEC materials have been developed over the last years. Apart from the conventional methods of cathode preparation, including high temperature calcination, mechanical grinding of powders, screen printing and sintering of thick fi lm layers, alternative synthesis and deposition routes are available. Nanocrystalline LSC or La 1−x Sr x Co 1−y Fe y O 3− δ thin fi lms on electrolyte substrates were already fabricated by pulsed laser deposition, [6][7][8][9] DC, and RF sputtering, [ 10,11 ] spray pyrolysis, [ 12 ] and sol-gel deposition. [13][14][15][16][17] In this work the chemical and structural properties and the stability of nanoscaled La 0.6 Sr 0.4 CoO 3− δ LSC thin fi lm cathodes on polycrystalline Gd 0.1 Ce 0.9 O 1.95 (CGO) substrates were investigated thoroughly. The fabrication by a low-temperature sol-gel technique is favorable for tailoring the grain size, porosity and cathode-fi lm thickness. [ 18 ] The electrochemical properties of the nanoscaled LSC thin fi lm cathodes were already reported by Hayd et al. who presented an outstanding electrochemical performance and extraordinary low area specifi c resistances as low as ASR chem = 0.023 Ω cm 2 at an operating temperature of 600 ° C. [ 19,20 ] Interestingly enough, theoretical models predicted ASR chem values up to one order of magnitude larger than the experimental data. For obvious reasons, the excellent performance of our nanoscaled cathodes does not solely depend on microstructure (porosity, increased inner surface area) as reported in previous work, [ 21 ] but presumably on the enhanced catalytic properties of the La 0.6 Sr 0.4 CoO 3− δ . However, the outstanding electrochemical performance motivates the analysis of the microstructure and phase composition of the LSC cathodes presented in this work.The nanoscaled LSC thin-fi lm cathodes were studied by transmission and scanning transmission electron microscopy (TEM/STEM) combined with energy-dispersive X-ray spectroscopy (EDXS). Moreover, high-angle annular dark-fi eld (HAADF) STEM tomography was used to study the distribution of the pores and quantify the porosity, which was not reported for nanoscaled (La,Sr)CoO 3 -based materials in literature before. Although several techniques like μ -tomography, [ 22 ] FIB-tomography, [ 23,24 ] transmission X-ray microscope based X-ray tomography, [ 12 , 25 ] mercury intrusion, [ 22 , 26 ] nitrogen adsorption, [ 27 ] or the Archimedes method [ 22 , 28 ]

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“…The former two are suitable for dense electrolyte or cathode layers, especially in the sub-micron range, while the latter is perhaps more suitable for porous cathode or anode layers. It is worth pointing out that by controlling the background pressure [16] and substrate temperature [17] during deposition and/or film thickness (as will be discussed later), it is possible to control the porosity in sputtered films. Accordingly, correlation between deposition parameters, post-deposition treatment, microstructure and conductivity of LSCF thin films needs to be characterised [18].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Microfabrication Considerations for Self‐Supported On‐Chip Ultra‐Thin Micro‐Solid Oxide Fuel Cell Membranes

et al. 2009

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La0.6Sr0.4Co0.8Fe0.2O3 – δ (LSCF) has been sputtered on bare Si and Si3N4 and yttria‐stabilised zirconia (YSZ) thin films to investigate annealing temperature‐ and thickness‐dependent microstructure and functional properties, as well as their implications for designing failure‐resistant micro‐solid oxide fuel cell (μSOFC) membranes. The LSCF thin films crystallise in the 400–450 °C range; however, after annealing in the 600–700 °C range, cracks are observed. The formation of cracks is also thickness‐dependent. High electrical conductivity, ∼520 Scm–1 at 600 °C, and low activation energy, ∼0.13 eV, in the 400–600 °C range, are still maintained for LSCF films as thin as 27 nm. Based on these studies, a strong correlation between microstructure and electrical conductivity has been observed and an annealing temperature‐thickness design space that is complementary to temperature‐stress design space has been proposed for designing reliable membranes using sputtered LSCF thin films. Microfabrication approaches that maintain the highest possible surface and interface quality of heterostructured membranes have been carefully examined. By taking advantage of the microstructure, microfabrication and geometrical structural considerations, we were able to successfully fabricate large‐area, self‐supported membranes. These results are also relevant to conventional or grid‐supported SOFC membranes using ultrathin nanocrystalline cathodes and μSOFCs using cathode thin films other than LSCF.

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Pulsed laser deposition of conducting porous La-Sr-Co-O films

Cited by 55 publications

References 7 publications

Direct Applicability of La_0.6Sr_0.4CoO_3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

Direct Applicability of La_0.6Sr_0.4CoO_3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Microstructure and Microfabrication Considerations for Self‐Supported On‐Chip Ultra‐Thin Micro‐Solid Oxide Fuel Cell Membranes

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Pulsed laser deposition of conducting porous La-Sr-Co-O films

Cited by 55 publications

References 7 publications

Direct Applicability of La0.6Sr0.4CoO3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

Direct Applicability of La0.6Sr0.4CoO3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

Microstructure of Nanoscaled La0.6Sr0.4CoO3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Microstructure and Microfabrication Considerations for Self‐Supported On‐Chip Ultra‐Thin Micro‐Solid Oxide Fuel Cell Membranes

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Direct Applicability of La_0.6Sr_0.4CoO_3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

Direct Applicability of La_0.6Sr_0.4CoO_3 – δ Thin Film Cathode to Yttria Stabilised Zirconia Electrolytes at T ≤ 650 °C

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells