Properties of Flame Sprayed Ce_0.8Gd_0.2O_1.9‐δ Electrolyte Thin Films

Abstract

Thin films of Ce0.8Gd0.2O1.9‐δ (CGO) are deposited by flame spray deposition with a deposition rate of about 30 nm min−1. The films (deposited at 200 °C) are dense, smooth, and particle‐free and show a biphasic amorphous/nanocrystalline microstructure. Isothermal grain growth and microstrain are determined as a function of dwell time and temperature and correlated to the electrical conductivity. CGO films annealed for 10 h at 600 °C present the best electrical conductivity of 0.46 S m−1 measured at 550 °C. Reasons for the superior performance of films annealed at low temperature over higher‐temperature‐treated samples are discussed and include grain‐size evolution, microstrain relaxation, and chemical decomposition. Nanoindentation measurements are conducted on the CGO thin films as a function of annealing temperature to determine the hardness and elastic modulus of the films for potential application as free‐standing electrolyte membranes in low‐temperature micro‐SOFCs (solid oxide fuel cells).

Flame spray deposition of La0.6Sr0.4CoO3−δ thin films: Microstructural characterization, electrochemical performance and degradation

“…The size of the grains in the nanocrystalline LSC films ranges from 21.4 ± 5 nm at 700 • C up to 124 ± 22 nm at 900 • C. Similar parabolic grain growth development with annealing temperature has also been reported for La 0.5 Sr 0.5 CoO 3−ı films prepared by sol-gel technique [48] and LSCF films prepared by spray pyrolysis and pulsed laser deposition [9]. Self-limited grain growth as reported in [60,69] was not found possibly due to the porous thin film microstructures. It is known from literature that occurrence of pores strongly affects the grain growth kinetics [70].…”

Time–Temperature–Transformation (TTT) Diagrams for Crystallization of Metal Oxide Thin Films

“…It has been shown that a large variety of processing possibilities exist to deposit solid, amorphous, metal oxide thin fi lms such as precipitation-based fi lm processing, [27][28][29] for example, spray pyrolysis, sol-gel, or fl ame-spray processing, and vacuum-based techniques, [ 27 , 30 ] for instance, pulsed laser deposition (PLD) or physical vapor deposition (PVD). All processing methods have in common that the amorphous thin fi lms crystallize upon annealing at temperatures above the deposition temperature.…”

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

“…Present‐day SOFCs usually consist of a strontium‐substituted lanthanum manganite/yttria‐stabilized zirconia (LSM/YSZ) cathode, an YSZ electrolyte, and a Ni/YSZ composite anode. Of the different approaches to lower the operating temperature several studies have focused on electrolytes and the ability to tailor the microstructure in order to greatly enhance the ionic conductivity 5–9…”

“…[5][6][7][8][9] Looking at the SOFC system perspective it is insufficient only to improve a single cell component in order to drastically increase the cell performance as it has been shown that all cell components (cathode, electrolyte, and anode) contribute with considerable losses in the SOFC. [10] Therefore, work on novel cathode materials is highly important.…”