Determination of oxygen nonstoichiometry and diffusivity in mixed conducting oxides by oxygen coulometric titration. 1: Chemical diffusion in La{sub 0.8}Sr{sub 0.2}CoO{sub 3{minus}{delta}}
Journal Article
·
· Journal of the Electrochemical Society
- Univ. of Twente, Enschede (Netherlands)
Mixed ionic and electronic conducting perovskites La{sup 1{minus}x}Sr{sub x}CoO{sub 3{minus}{delta}} receive wide attention to date because of their potential applications as gas separation membranes, oxidation catalysts, and as electrodes in solid oxide fuel cells and oxygen sensors. Oxygen coulometric titration has been applied to measure chemical diffusion in La{sub 0.8}Sr{sub 0.2}CoO{sub 3{minus}{delta}} between 700 and 1,000 C. The transient current response to a potentiostatic step has been transformed from the time domain to the frequency domain. The equivalent circuit used to fit the resulting impedance data contains the element that describes the finite-length diffusion of oxygen into the sample specimen. Other elements included are the gas-phase capacitance and the sum of the gas-phase diffusion resistance and that associated with the limited surface exchange kinetics of the sample. The chemical diffusion coefficient of perovskite La{sub 0.8}Sr{sub 0.2}CoO{sub 3{minus}{delta}} has been determined as a function of temperature and oxygen partial pressure. Its value can be represented by {tilde D} (cm{sup 2}/s) = 5.91 {times} exp [({minus}135 kJ/mol)/RT], and turns out to be practically independent of oxygen partial pressure in the range 10{sup {minus}2}--0.209 bar.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 509381
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 4 Vol. 144; ISSN JESOAN; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
Similar Records
Determination of oxygen nonstoichiometry and diffusivity in mixed conducting oxides by oxygen coulometric titration. 2: Oxygen nonstoichiometry and defect model for La{sub 0.8}Sr{sub 0.2}CoO{sub 3{minus}{delta}}
Comparison of oxygen permeability and stability of perovskite type La{sub 0.2}A{sub 0.8}Co{sub 0.2}Fe{sub 0.8}O{sub 3{minus}{delta}} (A = Sr, Ba, Ca) membranes
Oxygen nonstoichiometry of La sub 1 minus x Sr sub x CoO sub 3 minus. delta. (0 < x le 0. 6)
Journal Article
·
Mon Mar 31 23:00:00 EST 1997
· Journal of the Electrochemical Society
·
OSTI ID:509382
Comparison of oxygen permeability and stability of perovskite type La{sub 0.2}A{sub 0.8}Co{sub 0.2}Fe{sub 0.8}O{sub 3{minus}{delta}} (A = Sr, Ba, Ca) membranes
Journal Article
·
Sun Aug 01 00:00:00 EDT 1999
· Industrial and Engineering Chemistry Research
·
OSTI ID:691438
Oxygen nonstoichiometry of La sub 1 minus x Sr sub x CoO sub 3 minus. delta. (0 < x le 0. 6)
Journal Article
·
Sun Jul 01 00:00:00 EDT 1990
· Journal of Solid State Chemistry; (USA)
·
OSTI ID:6335894