In situ oxygen surface exchange coefficient measurements on lanthanum strontium ferrite thin films via the curvature relaxation method

Yang, Qing; Burye, Theodore E.; Lunt, Richard R.; Nicholas, Jason D.

doi:10.1016/j.ssi.2013.07.025

Cited by 32 publications

(52 citation statements)

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“…For instance, chemical oxygen surface exchange coefficient (k) discrepancies greater than 4 orders of magnitude are reported at identical temperature and oxygen partial pressure conditions for the MIEC material La 0.6 Sr 0.4 FeO 3-δ (LSF64). [10][11][12][13] Similarly, large k discrepancies have been observed for other MIEC materials such as lanthanum strontium cobalt iron oxide [14][15][16][17] and reduced cerium oxide. [18][19][20][21] Since recent studies have shown that strain can alter k, 20,21 it is likely that some of these observed k discrepancies are due to differences in MIEC stress state.…”

mentioning

confidence: 85%

“…• C. As done previously for experiments with 8 mol% YSZ substrates, 13 to relieve residual stress within the YSZ wafers the 13 mol% YSZ substrates used here were pre-annealed at 1100…”

Section: Methodsmentioning

confidence: 99%

“…Bilayer curvature measurements.-As described more fully in Yang et al, 13 bilayer curvature measurements were conducted using the controlled atmosphere multi-beam optical stress senor (MOSS) setup shown in Figure 1 and the geometrical relationship:…”

Section: Methodsmentioning

confidence: 99%

“…Assuming the bracketed quantities in Equation 13 remain constant and non-zero during small step changes in atmospheric p O 2 , Equation 8 can be rewritten using Equation 13 to describe the curvature relaxation of a dense thick film | inert substrate bilayer as:…”

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confidence: 99%

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Porous Thick Film Lanthanum Strontium Ferrite Stress and Oxygen Surface Exchange Bilayer Curvature Relaxation Measurements

Yang

Nicholas

2014

J. Electrochem. Soc.

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Here, the chemical oxygen surface exchange coefficient and film stress of porous La 0.6 Sr 0.4 FeO 3-δ (LSF64) thick films were simultaneously measured in situ between 275-375 • C and 275-700 • C, respectively, using a bilayer curvature measurement technique. The magnitude and activation energy of the porous LSF64 thick film oxygen surface exchange coefficients were consistent with those from large grained, bulk samples. However, unlike large-grained, dilatometry-tested bulk LSF64 samples that only exhibited measurable chemical stress above 525 • C, the fine-grained, curvature-tested porous LSF64 thick films studied here exhibited measurable chemical stress over the complete temperature range from 275 to 700 • C. Further, the porous LSF64 thick films exhibited a kink in their Arrhenius chemical stress behavior ( Oxygen-exchange-capable mixed ionic electronic conducting (MIEC) materials are widely used in electrochemical devices such as solid oxide fuel cells (SOFCs), 1-5 catalysts, 6,7 and gas separation membranes. 8,9 However, debate exists on the oxygen surface exchange rates of even the most-common MIEC materials. For instance, chemical oxygen surface exchange coefficient (k) discrepancies greater than 4 orders of magnitude are reported at identical temperature and oxygen partial pressure conditions for the MIEC material La 0.6 Sr 0.4 FeO 3-δ (LSF64). [10][11][12][13] Similarly, large k discrepancies have been observed for other MIEC materials such as lanthanum strontium cobalt iron oxide [14][15][16][17] and reduced cerium oxide. [18][19][20][21] Since recent studies have shown that strain can alter k, 20,21 it is likely that some of these observed k discrepancies are due to differences in MIEC stress state. Unfortunately, simultaneous k and stress state measurements on MIEC materials are largely absent from the literature. Here, the stress and oxygen surface exchange coefficients of porous LSF64 thick films atop single crystal (Y 2 O 3 ) 0.13 (ZrO 2 ) 0.87 (YSZ) substrates were simultaneously measured in situ using a new bilayer curvature measurement technique. Theoretical BackgroundPorous thick film stress measurement.-Stresses in dense thin films (i.e. those with film to substrate thickness ratios less than 1:1000) can be rigorously extracted from bilayer curvature measurements using Stoney's Equation:whereλ St is the thickness averaged film stress predicted from Stoney's Equation, κ is the bilayer curvature, h s is the substrate thickness, h f is the film thickness, and M S is the substrate biaxial modulus defined as E S / (1 − υ S ) where E S is substrate Young's modulus and υ S is the substrate Poisson's Ratio. 22,23 Stoney's equation is convenient because the thickness averaged film stress (λ) (which is the same as the stress at each point in the film due to the film's thinness) can be extracted * Electrochemical Society Student Member.* * Electrochemical Society Active Member. z E-mail: jdn@msu.edu from bilayer curvature measurements without knowledge of the film elastic properties. In contrast, stre...

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confidence: 85%

“…• C. As done previously for experiments with 8 mol% YSZ substrates, 13 to relieve residual stress within the YSZ wafers the 13 mol% YSZ substrates used here were pre-annealed at 1100…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Porous Thick Film Lanthanum Strontium Ferrite Stress and Oxygen Surface Exchange Bilayer Curvature Relaxation Measurements

Yang

Nicholas

2014

J. Electrochem. Soc.

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“…Yang et al and Sheldon et al made in situ measurements of the curvature of thin films of La 0.6 Sr 0.4 FeO 3−δ and ceria, respectively, using multi-beam optical stress sensors (MOSS) [32,33]. Yang et al used these measurements to determine film stress and chemical oxygen surface exchange coefficients as functions of temperature and oxygen partial pressure, while Sheldon et al related compositional stresses to grain boundary width and established the influence of space charge effects on oxygen incorporation thermodynamics.…”

Section: Chemical Structural and Morphologicalmentioning

confidence: 99%

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

et al. 2014

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Functional materials for energy conversion and storage exhibit strong coupling between electrochemistry and mechanics. For example, ceramics developed as electrodes for both solid oxide fuel cells and batteries exhibit cyclic volumetric expansion upon reversible ion transport. Such chemomechanical coupling is typically far from thermodynamic equilibrium, and thus is challenging to quantify experimentally and computationally. In situ measurements and atomistic simulations are under rapid development to explore how this coupling can be used to potentially improve both device performance and durability. Here, we review the commonalities of coupling between electrochemical and mechanical states in fuel cell and battery materials, illustrating with specific cases the progress in materials processing, in situ characterization, and computational modeling and simulation. We also highlight outstanding questions and opportunities in these applications -both to better understand the limiting mechanisms within the materials and to significantly advance the durability and predictability of device performance required for renewable energy conversion and storage.

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In Situ Optical Absorption Studies of Point Defect Kinetics and Thermodynamics in Oxide Thin Films

Buckner

Perry

2019

Adv Materials Inter

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The authors review the use of in situ optical absorption to probe point defect equilibria and kinetics in oxides, with particular attention to thin films and high temperature measurements evaluating changes in oxygen content. The introduction notes the impact of point defects on oxide behavior, including differences in thin films vs. bulk materials, and describes methods to evaluate point defect equilibria and kinetics; advantages of optical absorption among these methods are highlighted. Section 2 provides an overview of how optical absorption and point defect concentrations are related, including various possible structural and electronic origins of defect-mediated absorption changes corresponding to oxygen content changes. Section 3 traces the development of historical understanding of optical absorption in nonstoichiometric oxides and emergence of thin film applications and measurement approaches that resulted. Section 4 details the procedure for determining surface exchange coefficients from optical transmission relaxation measurements and provides specific examples of how this approach uniquely has enabled new insights into thin film surface exchange behavior with and without current collectors. Section 5 provides examples of optically-derived diffusivity measurements and comparisons of bulk and thin This article is protected by copyright. All rights reserved. 2 film defect equilibria. Section 6 outlines potential opportunities and future developments in this area, and Section 7 concludes the manuscript.

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In situ oxygen surface exchange coefficient measurements on lanthanum strontium ferrite thin films via the curvature relaxation method

Cited by 32 publications

References 50 publications

Porous Thick Film Lanthanum Strontium Ferrite Stress and Oxygen Surface Exchange Bilayer Curvature Relaxation Measurements

Porous Thick Film Lanthanum Strontium Ferrite Stress and Oxygen Surface Exchange Bilayer Curvature Relaxation Measurements

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

In Situ Optical Absorption Studies of Point Defect Kinetics and Thermodynamics in Oxide Thin Films

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