Oxygen Transport in Oxide Thin Film Structures Oriented La[sub 0.5]Sr[sub 0.5]CoO[sub 3−x] on Single-Crystal Yttria-Stabilized Zirconia

Abstract

Oriented thin films of La 0.5 Sr 0.5 CoO 3-x were deposited on single-crystal 9.5 mol% Y 2 O 3 stabilized ZrO 2 by laser deposition. The films were infused with 18 O by exchange with 20 kPa O 2 at 300-400°C, then quenched and depth profiled by secondary ion mass spectroscopy. Analysis of the depth profiles revealed a significant barrier to interfacial transport at these relatively low temperatures.

Factors Governing Oxygen Reduction in Solid Oxide Fuel Cell Cathodes

“…The author's isotope-exchange measurements on the same system confirm that the film contributes virtually no resistance to bulk oxygen transport and that there is no resistance for 18 O 2- / 16 O 2- exchange across the LSC/CDC interface. Subsequently published studies have consistently confirmed these findings for other perovskite phases having high ionic conductivities. ,,− Both Kawada et al . and Yang et al .…”

“…To better understand the role of bulk oxygen transport in determining the characteristics of mixed-conducting oxide electrodes, workers have focused considerable attention in the last 10−12 years on dense thin-film electrodes having little or no three-phase boundary contact area. ,,− Early attempts struggled with sample preparation, it being difficult to make and verify the existence of uncracked and dense films. Perhaps the first success in this direction was that of Mizusaki and co-workers, who used a pulsed KrF excimer laser to flash evaporate and deposit 1−2 μm thick films of La 0.5 Sr 0.5 MnO 3 on YSZ.…”

In Situ XPS Studies of Perovskite Oxide Surfaces under Electrochemical Polarization

“…La 0.5 Sr 0.5 CoO 3- x Cell Preparation. The LSCO thin film−YSZ single crystal composite was supplied by Allan Jacobson (University of Houston) and has been previously described …”

“…The La 1 - x Sr x CoO 3 - δ class of materials are metallic or semimetallic conductors 41,68,69 whose conductivities also decrease upon reduction. In addition to this general interest in cobaltite perovskites, we had access to high quality, highly oriented thin films of this material and had previously investigated oxygen activation and permeation through these thin film materials …”

SrCoO 3−δ thin films by atomic layer deposition

“…Therefore the cathode performance is usually the rate-limiting step in the IT-SOFCs [5]. Consequently, further improvement of the IT-SOFC performance requires either the development of novel high-performance cathode materials optimized for the intermediate-temperature operation, or increasing the active surface area of the existing cathode materials [6,7], as the electrode reaction rate has been observed to be limited by the oxygen surface exchange reaction rate, and thus the cathode surface area [8,9].…”